Gerald L. HURST's Chemistry and Explosives - UseNet Articles Collection File 1 of 2: CHEMISTRY All of his articles to rec.pyrotechnics and alt.engr.explosives since 1995 This file is available at: http://www.geocities.com/CollegePark/Library/4196 and at: http://members.xoom.com/explosive ****************************************************************************** Gerald L. Hurst, AKA Jerry (Ico), is a Cambridge Ph.D. chemist with experience in explosives and fire-related matters, having been Chief Scientist of the Atlas Powder Company, the then largest explosives manufacturer in the U.S.: he developed the trade secret formulas for Liquid Paper (Gillette), patented the so-called "Mylar" balloons (the metallized helium balloons found in super- markets), Astrolite A-1-5 (coinventor) and the best-known Kinepak binary explosive. He has an extensive forensic experience in arson/murder cases dating back 30 years: much of his present work involves the analysis of fires and explosions to determine the cause and origin. All of his amazing posts since early 1995 have been collected in two single files to spare the reader a lot of on-line time, since the original Deja News' files exceed 10 MB. Each article is a trustworthy source of the finest informations on its own subject freely available on the Internet: Jerry's brilliant, accurate and helpful style really stretches one's thinking on a wide variety of matters, most notably chemistry and explosives, making both the budding and the skilled chemist learn and smile at the same time. ****************************************************************************** 1. 1995/03/29 DOC0001 Re: Activities vs. Concentrations: Opinions Sough 2. 1995/03/29 DOC0002 Re: Ohmic Heating 3. 1995/03/29 DOC0003 Re: Ohmic Heating 4. 1995/03/29 DOC0004 Re: Oxygen solubility Deuterium oxide? 5. 1995/04/01 DOC0005 Re: glass reaction 6. 1995/04/07 DOC0006 Re: Nitro Cellulose 7. 1995/04/08 DOC0007 Re: N2O 8. 1995/04/08 DOC0008 Re: fingerprints:how?... 9. 1995/04/09 DOC0009 Re: help getting co2 from air 10. 1995/04/11 DOC0010 Re: Common Ion Effect qesution 11. 1995/04/11 DOC0011 Re: Question on dessicant 12. 1995/04/11 DOC0012 Re: Quick question on water 13. 1995/04/11 DOC0013 Re: Quick question on water 14. 1995/04/11 DOC0014 Re: Renaming SCI.CHEM; or "Are chemists 15. 1995/04/11 DOC0015 Re: Searchable Online Journal Databases? 16. 1995/04/11 DOC0016 Re: Solubility Of Gases 17. 1995/04/11 DOC0017 Re: cyanide reagent 18. 1995/04/14 DOC0018 Re: Sarin 19. 1995/04/15 DOC0019 Re: Picrates 20. 1995/04/15 DOC0020 Re: Toothpaste & OJ 21. 1995/04/15 DOC0021 Re: help: What is definition of Binding Energy? 22. 1995/04/16 DOC0022 Re: CAN ANYONE IDENTIFY THIS CHEMICAL: C_3 H_8 (N 23. 1995/04/16 DOC0023 Re: CHEMICAL ENGINEERING 24. 1995/04/16 DOC0024 Re: Question on dessicant 25. 1995/04/16 DOC0025 Re: Question on dessicant 26. 1995/04/18 DOC0026 Re: Vinegar and Acetic Acid 27. 1995/04/18 DOC0027 Re: help with g92 calculations. 28. 1995/04/18 DOC0028 Re: nalgene tubing rupture 29. 1995/04/20 DOC0029 Re: Mercurous Perchlorate 30. 1995/04/25 DOC0030 Re: Cyanogenbromide (BrCN) 31. 1995/04/26 DOC0031 Re: oxidation-reduction reactions 32. 1995/05/08 DOC0032 Re: 1Ammoniun Nitrate 33. 1995/05/08 DOC0033 Re: 1Ammoniun Nitrate 34. 1995/05/08 DOC0034 Re: Geometry Q in sci.chem? 35. 1995/05/08 DOC0035 Re: h202 as oxidising agent 36. 1995/05/09 DOC0036 Re: 1Ammoniun Nitrate 37. 1995/05/09 DOC0037 Re: Please help: Brownian Motion 38. 1995/05/09 DOC0038 Re: diesel fuel/kerosene 39. 1995/05/09 DOC0039 Re: keeping CO2 liquid ? 40. 1995/05/17 DOC0040 Re: A: How to glue polyethylene or polypropylene 41. 1995/05/17 DOC0041 Re: ANSWER TO NOT SO HARD CHEMISTRY A-LEVEL QUEST 42. 1995/05/17 DOC0042 Re: ANSWER TO NOT SO HARD CHEMISTRY A-LEVEL QUEST 43. 1995/05/17 DOC0043 Re: ANSWER TO NOT SO HARD CHEMISTRY A-LEVEL QUEST 44. 1995/05/17 DOC0044 Re: ANSWER TO NOT SO HARD CHEMISTRY A-LEVEL QUEST 45. 1995/05/17 DOC0045 Re: MISSING USGS RECORDS OF 04/19/95 46. 1995/05/17 DOC0046 Re: Rust? stains on concrete 47. 1995/05/17 DOC0047 Re: Tagging ammonium nitrate (or something like t 48. 1995/05/17 DOC0048 Re: sodium azide 49. 1995/05/18 DOC0049 Re: Lawsuit against fertilizer mfr (Okl city bomb 50. 1995/05/18 DOC0050 Re: me on TV in Boston WCVB 51. 1995/05/19 DOC0051 Re: Gallium Oxide 52. 1995/05/19 DOC0052 Re: Lawsuit against fertilizer mfr (Okl city bomb 53. 1995/05/19 DOC0053 Re: Lawsuit against fertilizer mfr (Okl city bomb 54. 1995/05/20 DOC0054 Re: Speed of combustion of gasoline 55. 1995/05/20 DOC0055 Re: Speed of combustion of gasoline 56. 1995/05/21 DOC0056 Re: ANSWER TO NOT SO HARD CHEMISTRY A-LEVEL QUEST 57. 1995/05/21 DOC0057 Re: Glass 58. 1995/05/21 DOC0058 Re: Use of Perchloric acid in non-perchloric acid 59. 1995/05/21 DOC0059 Re: salt & ice. Cool beer question 60. 1995/05/22 DOC0060 Re: Results - Was "Sugar and Diet Coke" 61. 1995/05/23 DOC0061 Re: salt & ice. Cool beer question 62. 1995/05/24 DOC0062 Re: salt & ice. Cool beer question 63. 1995/05/24 DOC0063 Re: salt & ice. Cool beer question 64. 1995/05/25 DOC0064 Re: Flash Point (Was: toxicity) 65. 1995/05/25 DOC0065 Re: salt & ice. Cool beer question 66. 1995/05/25 DOC0066 Re: salt & ice. Cool beer question 67. 1995/05/26 DOC0067 Re: salt & ice. Cool beer question 68. 1995/05/30 DOC0068 Re: Cleaning Silver in the Home? 69. 1995/05/30 DOC0069 Re: crystals 70. 1995/06/05 DOC0070 Re: Flash Point (Was: toxicity) 71. 1995/06/19 DOC0071 Re: Fluorine gas 72. 1995/06/19 DOC0072 Re: Your view:fundamental question in ENTROPY 73. 1995/06/20 DOC0073 Re: Exlosives 2nd try 74. 1995/06/20 DOC0074 Re: Your view:fundamental question in ENTROPY 75. 1995/06/26 DOC0075 Gas expansion and plate velocities 76. 1995/06/26 DOC0076 Re: Gas expansion and plate velocities 77. 1995/06/26 DOC0077 Re: H2S instead of H2O 78. 1995/07/03 DOC0078 Re: What are HCI and NaOH???? 79. 1995/07/09 DOC0079 Re: help! where can i buy iron sulfide?! (or ma 80. 1995/07/26 DOC0080 Re: Need info on cryogenics 81. 1995/08/03 DOC0081 Re: Need help finding C-N compounds 82. 1995/08/06 DOC0082 Re: Twink - What's in it? 83. 1995/08/07 DOC0083 Re: Ammonia gas removal from air. 84. 1995/08/07 DOC0084 Re: Ceramic-filled Paint 85. 1995/08/07 DOC0085 Re: The quick & easy "lava lamp" 86. 1995/08/07 DOC0086 Re: Twink - What's in it? 87. 1995/08/08 DOC0087 Re: Potassium Permanganate - What is it? 88. 1995/08/08 DOC0088 Re: RECIPE FOR NITROGEN TRI IODIDE WANTED 89. 1995/08/08 DOC0089 Re: Titration of Nitric Acid with Sodium Hydroxid 90. 1995/08/08 DOC0090 Re: Twink - What's in it? 91. 1995/08/08 DOC0091 Re: imperial units to si units conversion 92. 1995/08/08 DOC0092 Re: sucrose density 93. 1995/08/16 DOC0093 Re: Twink - What's in it? 94. 1995/08/16 DOC0094 Re: sucrose density 95. 1995/08/18 DOC0095 Re: sucrose density 96. 1995/08/27 DOC0096 Re: colloidal potassium 97. 1995/08/27 DOC0097 Re: sucrose density 98. 1995/08/27 DOC0098 Re: sucrose density 99. 1995/08/28 DOC0099 Re: ethanol(spell check!!!) 100. 1995/08/29 DOC0100 Re: A specific general chem question 101. 1995/08/29 DOC0101 Re: A specific general chem question 102. 1995/08/29 DOC0102 Re: Why thinking hurts - was Re: sucrose density 103. 1995/08/29 DOC0103 Re: colloidal potassium 104. 1995/08/30 DOC0104 Re: PH Question 105. 1995/08/30 DOC0105 Re: PH Question 106. 1995/08/30 DOC0106 Re: PH Question 107. 1995/08/31 DOC0107 Re: PH Question 108. 1995/09/01 DOC0108 Re: chemistry 109. 1995/09/01 DOC0109 Re: dumb question : water or ice - which denser? 110. 1995/09/01 DOC0110 Re: dumb question : water or ice - which denser? 111. 1995/09/02 DOC0111 Re: dumb question : water or ice - which denser? 112. 1995/09/02 DOC0112 Re: sucrose density 113. 1995/09/03 DOC0113 Re: FREON 12 Substitutes - Whadda ya know? 114. 1995/09/04 DOC0114 Re: Help needed: Why is hydrogen floride toxic ? 115. 1995/09/06 DOC0115 Re: temp decrease in soda cans 116. 1995/09/12 DOC0116 Re: question re: freezing point depression 117. 1995/09/13 DOC0117 Re: [Q] cold trap 118. 1995/09/15 DOC0118 Re: Aluminum plate to clean tarnish off silver wo 119. 1995/09/15 DOC0119 Re: Beginner's question 120. 1995/09/17 DOC0120 Re: Beginner's question 121. 1995/09/24 DOC0121 Re: MIT engineers; how they spend their time and 122. 1995/09/24 DOC0122 Re: nitrite to nitric oxide 123. 1995/09/25 DOC0123 Re: Archimedes (was Re: Horst teaches . . .) 124. 1995/09/25 DOC0124 Re: WHO is MIT engineer Decobert's boss there at 125. 1995/09/28 DOC0125 Re: Minimum Coulomb Interactions for plutonium 126. 1995/09/28 DOC0126 Re: Minimum Coulomb Interactions for plutonium 127. 1995/09/30 DOC0127 Re: ALUMINUM BOMB 128. 1995/09/30 DOC0128 Re: question!!!!! 129. 1995/10/03 DOC0129 Re: Impact of chemistry on philosophy? 130. 1995/10/03 DOC0130 Re: what is flash point? 131. 1995/10/07 DOC0131 Re: what is flash point? 132. 1995/10/08 DOC0132 Re: definition of isodesmic??? 133. 1995/10/08 DOC0133 Re: what is flash point? 134. 1995/10/10 DOC0134 Re: what is flash point? 135. 1995/10/10 DOC0135 Re: what is flash point? 136. 1995/10/12 DOC0136 Re: what is flash point? 137. 1995/10/13 DOC0137 Re: Nitrogen Triiodide 138. 1995/10/16 DOC0138 Re: H2O Bridges 139. 1995/10/25 DOC0139 Re: Hints on building a freeze dryer 140. 1995/10/25 DOC0140 Re: Where did the MOLE come from? 141. 1995/10/26 DOC0141 Re: Weighing metals (Jason) 142. 1995/10/28 DOC0142 Re: Chemistry Problem..(Please help!) 143. 1995/10/29 DOC0143 Re: Hot Water 144. 1995/10/29 DOC0144 Re: Hot Water 145. 1995/10/29 DOC0145 Re: QUESTION: (bio)chemistry of popcorn 146. 1995/10/29 DOC0146 Re: Where did the MOLE come from? 147. 1995/10/29 DOC0147 Re: thermochemistry question 148. 1995/10/30 DOC0148 Re: thermochemistry question 149. 1995/10/30 DOC0149 Re:solubility of gasses in liquids:QUESTION 150. 1995/11/03 DOC0150 Re: *so* sorry and glad 151. 1995/11/03 DOC0151 Re: Copper + Silver nitrate-----> *Please Help 152. 1995/11/04 DOC0152 Re: Additive to make paint glow 153. 1995/11/04 DOC0153 Re: exothermic reactions 154. 1995/11/05 DOC0154 Re: Endothermic Reaction 155. 1995/11/06 DOC0155 Re: thermochemistry question 156. 1995/11/07 DOC0156 Re: Dancing mothballs? 157. 1995/11/09 DOC0157 Re: sodium hypochlorite (bleach) and organic impu 158. 1995/11/13 DOC0158 Re: Caloric Value 159. 1995/11/13 DOC0159 Re: Coulombic forces 160. 1995/11/13 DOC0160 Re: delta H question 161. 1995/11/13 DOC0161 Re: delta H question 162. 1995/11/14 DOC0162 Re: odor of acetamide? 163. 1995/11/16 DOC0163 Re: Quiz question - please help 164. 1995/11/16 DOC0164 Re: Quiz question - please help 165. 1995/11/20 DOC0165 Re: Liquid Paper Solvent 166. 1995/11/20 DOC0166 Re: Question... 167. 1995/11/21 DOC0167 Re: U-In8: First Commercial Cold Fusion Cell? 168. 1995/11/22 DOC0168 Re: Swallow Me 169. 1995/11/24 DOC0169 Re: Swallow Me 170. 1995/11/24 DOC0170 Re: Swallow Me 171. 1995/11/29 DOC0171 Re: Air Fuel Mixture Ionization 172. 1995/12/02 DOC0172 Re: Bubbling in soda. 173. 1995/12/05 DOC0173 Re: Bubbling in soda. 174. 1995/12/17 DOC0174 Re: Chemie und deutsch 175. 1995/12/19 DOC0175 Re: SEMTEX - what is it? 176. 1995/12/20 DOC0176 Re: Freezing hot water 177. 1995/12/20 DOC0177 Re: Freezing hot water 178. 1995/12/21 DOC0178 Re: SEMTEX - what is it? 179. 1995/12/21 DOC0179 Re: SEMTEX - what is it? 180. 1995/12/21 DOC0180 Re: SEMTEX - what is it? 181. 1995/12/21 DOC0181 Re: SEMTEX - what is it? 182. 1995/12/21 DOC0182 Re: calcium carbonate in iron pipes question 183. 1995/12/23 DOC0183 Re: Thermal decomp of Ammon Phosphate ? 184. 1995/12/27 DOC0184 Re: Elevation of boiling point? 185. 1995/12/28 DOC0185 Re: Elevation of boiling point? 186. 1995/12/29 DOC0186 Re: PRAYER, Tue 26 Dec 1995 Overdose sermon 187. 1995/12/29 DOC0187 Re: blue sky & ozone 188. 1995/12/30 DOC0188 Re: Decomposition of Ammonium Nitrate 189. 1995/12/31 DOC0189 Re: blue sky & ozone 190. 1995/12/31 DOC0190 Re: blue sky & ozone 191. 1996/01/01 DOC0191 Re: blue sky & ozone 192. 1996/01/04 DOC0192 Re: Nitroglycerine (medicine), storage & hand 193. 1996/01/04 DOC0193 Re: PRAYER, Sun 31 Dec 1995 Carbon in us, Carbon 194. 1996/01/04 DOC0194 Re: Vapour Pressure - Mixtures 195. 1996/01/06 DOC0195 Re: 'Lavalamp'- which fluids are used ? 196. 1996/01/06 DOC0196 Re: New definition or concept: Half-life of One s 197. 1996/01/06 DOC0197 Re: New definition or concept: Half-life of One s 198. 1996/01/07 DOC0198 Re: Fresh water from sea water - new economical p 199. 1996/01/07 DOC0199 Re: Magnesium 200. 1996/01/08 DOC0200 Re: Fresh water from sea water - new economical p 201. 1996/01/08 DOC0201 Re: Fresh water from sea water - new economical p 202. 1996/01/08 DOC0202 Re: Ozone layer/Dobson Units 203. 1996/01/09 DOC0203 Re: Fresh water from sea water - new economical p 204. 1996/01/09 DOC0204 Re: Red Mercury 205. 1996/01/10 DOC0205 Re: Fresh water from sea water - new economical p 206. 1996/01/10 DOC0206 Re: Fresh water from sea water - new economical p 207. 1996/01/11 DOC0207 Re: Fresh water from sea 208. 1996/01/11 DOC0208 Re: Fresh water from sea 209. 1996/01/11 DOC0209 Re: Fresh water from sea water - new economical p 210. 1996/01/11 DOC0210 Re: Fresh water from sea water - new economical p 211. 1996/01/11 DOC0211 Re: What is the difference between KEROSINE oil a 212. 1996/01/13 DOC0212 Re: 12 Yr Old Son Science Exp. - Need Help! 213. 1996/01/13 DOC0213 Re: Endothermic Reactions 214. 1996/01/13 DOC0214 Re: Fresh water from sea water - new economical p 215. 1996/01/13 DOC0215 Re: What is the difference between KEROSINE oil a 216. 1996/01/13 DOC0216 Re: oklahoma explosive 217. 1996/01/14 DOC0217 Re: normality 218. 1996/01/14 DOC0218 Re: normality 219. 1996/01/15 DOC0219 Re: Oxygen & hydrogen combine??? What exactly 220. 1996/01/15 DOC0220 Re: Water injection into 221. 1996/01/15 DOC0221 Re: oklahoma explosive 222. 1996/01/15 DOC0222 Re: resistance of solution 223. 1996/01/16 DOC0223 Re: ammonia powder 224. 1996/01/17 DOC0224 Re: 35% of h2o2 means how many volumes ????? 225. 1996/01/17 DOC0225 Re: Cyanide ingestion 226. 1996/01/18 DOC0226 Re: Picric acid safety 227. 1996/01/19 DOC0227 Re: Amonnium Nitrate (& other people's proble 228. 1996/01/19 DOC0228 Re: Amonnium Nitrate (& other people's proble 229. 1996/01/20 DOC0229 Re: CaHCl 230. 1996/01/22 DOC0230 Re: Fresh water from sea water - new economical p 231. 1996/01/22 DOC0231 Re: low temp flames? 232. 1996/01/23 DOC0232 Re: Solubility of NO2 in water 233. 1996/01/24 DOC0233 Re: Blending Talcolm Powder 234. 1996/01/24 DOC0234 Re: Blending Talcolm Powder 235. 1996/01/24 DOC0235 Re: Fresh water from sea water - new economical p 236. 1996/01/24 DOC0236 Re: Melting rate of ice cubes 237. 1996/01/24 DOC0237 Re: Melting rate of ice cubes 238. 1996/01/26 DOC0238 Re: Archival Plastics 239. 1996/01/26 DOC0239 Re: Endothermic Reactions 240. 1996/01/26 DOC0240 Re: HELP!!! superfluidity/liquid helium 241. 1996/01/26 DOC0241 Re: HELP!!! superfluidity/liquid helium 242. 1996/01/26 DOC0242 Re: Molar masses does't work. 243. 1996/01/26 DOC0243 Re: Vapor Pressure Determination 244. 1996/01/27 DOC0244 Re: Why is this pH 13+? 245. 1996/01/28 DOC0245 Re: Who to complain to about Plutonium. 246. 1996/01/28 DOC0246 Re: Who to complain to about Plutonium. 247. 1996/01/29 DOC0247 Re: Pressure of liquid N2 at room temprature. 248. 1996/01/29 DOC0248 Re: What is the freezing point of water??? 249. 1996/01/29 DOC0249 Re: Why is this pH 13+? 250. 1996/02/17 DOC0250 Re: Volcano 251. 1996/02/18 DOC0251 Re: Analog of Capillary condensation 252. 1996/02/18 DOC0252 Re: HELP PLEASE!!! 253. 1996/02/18 DOC0253 Re: Science Fair Cold Pack Salts 254. 1996/02/19 DOC0254 Re: CO2 in coke 255. 1996/02/19 DOC0255 Re: Science Fair Cold Pack Salts 256. 1996/02/21 DOC0256 Re: Explosives -- academic research and career ch 257. 1996/02/22 DOC0257 Re: [Q] Best way to keep fizz in drinks 258. 1996/02/23 DOC0258 Re: Does Heat Speed Up or Slow Down a Chem 259. 1996/02/23 DOC0259 Re: Minority Postdoctoral Fellowship Opportunity 260. 1996/02/23 DOC0260 Re: Minority Postdoctoral Fellowship Opportunity 261. 1996/02/24 DOC0261 Re: Copper/Cupric Oxide Question 262. 1996/02/24 DOC0262 Re: Copper/Cupric Oxide Question 263. 1996/02/24 DOC0263 Re: Does Heat Speed Up or Slow Down a Chem 264. 1996/02/24 DOC0264 Re: [Q] Boiling water at low pressure 265. 1996/02/24 DOC0265 Re: [Q] Boiling water at low pressure 266. 1996/02/24 DOC0266 Re: [Q] Boiling water at low pressure 267. 1996/02/25 DOC0267 Re: Does Heat Speed Up or Slow Down a Chem 268. 1996/02/25 DOC0268 Re: [Q] Boiling water at low pressure 269. 1996/02/26 DOC0269 Re: Does Heat Speed Up or Slow Down a Chem 270. 1996/02/26 DOC0270 Re: Does Heat Speed Up or Slow Down a Chem 271. 1996/02/27 DOC0271 Re: Does Heat Speed Up or Slow Down a Chem 272. 1996/02/28 DOC0272 Re: Does Heat Speed Up or Slow Down a Chem 273. 1996/02/28 DOC0273 Re: How to melt magnesium ? 274. 1996/02/29 DOC0274 Re: What is the temprature at which paper burns? 275. 1996/02/29 DOC0275 Re: liquid heavier than water? 276. 1996/03/01 DOC0276 Re: non exothermic 277. 1996/03/02 DOC0277 Re: How to melt magnesium ? 278. 1996/03/02 DOC0278 Re: [Q] Boiling water at low pressure 279. 1996/03/03 DOC0279 Re: What is Baume? 280. 1996/03/07 DOC0280 Re: [Q] Energy of atoms in molecules 281. 1996/03/09 DOC0281 Re: How did he die? 282. 1996/03/09 DOC0282 Re: Mineral Spirits of Kerosene 283. 1996/03/11 DOC0283 Re: supersaturation problems -- help us!! 284. 1996/03/13 DOC0284 Re: Help with solubilities / mixed salts 285. 1996/03/13 DOC0285 Re: Help with solubilities / mixed salts 286. 1996/03/13 DOC0286 Re: [Q] Energy of atoms in molecules 287. 1996/03/14 DOC0287 Re: Dehumidifier efficiency 288. 1996/03/14 DOC0288 Re: Dehumidifier efficiency 289. 1996/03/14 DOC0289 Re: Help with solubilities / mixed salts 290. 1996/03/14 DOC0290 Re: Is CaCl2 a good humidity absorber to protect 291. 1996/03/14 DOC0291 Re: Making pure ammonium nitrate from fertilizer 292. 1996/03/14 DOC0292 Re: Mineral Spirits of Kerosene 293. 1996/03/14 DOC0293 Re: Nitrogen Dioxide Question 294. 1996/03/14 DOC0294 Re: Solvent: Mineral spirit ? 295. 1996/03/14 DOC0295 Re: [Q] Energy of atoms in molecules 296. 1996/03/14 DOC0296 Re: [Q] Energy of atoms in molecules 297. 1996/03/15 DOC0297 Re: Dehumidifier efficiency 298. 1996/03/15 DOC0298 Re: Is CaCl2 a good humidity absorber to protect 299. 1996/03/15 DOC0299 Re: [Q] Energy of atoms in molecules 300. 1996/03/15 DOC0300 Re: [Q] Energy of atoms in molecules 301. 1996/03/15 DOC0301 Re: liquid/solid thermometer..is it possible?? 302. 1996/03/16 DOC0302 Re: Phase Changes: water 303. 1996/03/16 DOC0303 Re: [Q] Energy of atoms in molecules 304. 1996/03/17 DOC0304 Re: Immobilization of carbon dioxide 305. 1996/03/17 DOC0305 Re: [Q] Energy of atoms in molecules 306. 1996/03/17 DOC0306 Re: [Q] Energy of atoms in molecules 307. 1996/03/17 DOC0307 Re: [Q] Energy of atoms in molecules 308. 1996/03/18 DOC0308 Re: Immobilization of carbon dioxide 309. 1996/03/19 DOC0309 Re: Immobilization of carbon dioxide 310. 1996/03/19 DOC0310 Re: Phase Changes: water 311. 1996/03/19 DOC0311 Re: Phase Changes: water 312. 1996/03/19 DOC0312 Re: [Q] Energy of atoms in molecules 313. 1996/03/19 DOC0313 Re: [Q] Energy of atoms in molecules 314. 1996/03/19 DOC0314 Re: [Q] Energy of atoms in molecules 315. 1996/03/19 DOC0315 Re: [Q] Energy of atoms in molecules 316. 1996/03/20 DOC0316 Re: A question about carbondioxide 317. 1996/03/20 DOC0317 Re: Blowing Bubbles 318. 1996/03/20 DOC0318 Re: Immobilization of carbon dioxide 319. 1996/03/20 DOC0319 Re: Immobilization of carbon dioxide 320. 1996/03/20 DOC0320 Re: Phase Changes: water 321. 1996/03/20 DOC0321 Re: [Q] Energy of atoms in molecules 322. 1996/03/20 DOC0322 Re: patron saint 323. 1996/03/21 DOC0323 Re: Immobilization of carbon dioxide 324. 1996/03/21 DOC0324 Re: Immobilization of carbon dioxide 325. 1996/03/22 DOC0325 Re: CO2 Reaction Question 326. 1996/03/24 DOC0326 Re: CO2 Reaction Question 327. 1996/03/26 DOC0327 Re: CO2 Reaction Question 328. 1996/03/26 DOC0328 Re: CopperChloride 329. 1996/03/26 DOC0329 Re: Know your limits ! (reply) 330. 1996/03/28 DOC0330 Re: looking for info... 331. 1996/04/01 DOC0331 Re: Immobilization of carbon dioxide 332. 1996/04/04 DOC0332 Re: Help with salt water density 333. 1996/04/06 DOC0333 Re: What food holds the most heat? Potato? 334. 1996/04/07 DOC0334 Re: high temp reactions 335. 1996/04/08 DOC0335 Re: Help with salt water density 336. 1996/04/08 DOC0336 Re: Semi skimmed milk 337. 1996/04/10 DOC0337 Re: throwing boiling water into freezing air 338. 1996/04/12 DOC0338 Singed Hair 339. 1996/04/21 DOC0339 SONIA DIDN'T DO IT. 340. 1996/04/26 DOC0340 Re: SONIA DIDN'T DO IT. 341. 1996/04/26 DOC0341 Re: SONIA DIDN'T DO IT. 342. 1996/04/26 DOC0342 Re: SONIA DIDN'T DO IT. 343. 1996/04/29 DOC0343 Re: SONIA DIDN'T DO IT. 344. 1996/04/29 DOC0344 Re: SONIA DIDN'T DO IT. 345. 1996/04/30 DOC0345 Re: SONIA DIDN'T DO IT. 346. 1996/05/02 DOC0346 Re: SONIA DIDN'T DO IT. 347. 1996/05/10 DOC0347 Re: Unka Al groupies 348. 1996/05/21 DOC0348 Re: Dangerous/Illegal Demonstrations 349. 1996/05/22 DOC0349 Re: Dangerous/Illegal Demonstrations 350. 1996/05/22 DOC0350 Re: Lifting capacity of helium 351. 1996/06/09 DOC0351 SONIA DIDN'T DO IT 352. 1996/11/03 DOC0352 Coal tar solvent naphtha compositions 353. 1997/02/14 DOC0353 Re: Lye/Aluminum reactor? DOC0001 Subject: Re: Activities vs. Concentrations: Opinions Sought! From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/03/29 Message-ID: <3lcg9o$75p@Sierra.onr.com> Newsgroups: sci.chem , I was told (and have read) that the simpler molar-concentration >: approach is (or can be) considerably less accurate in predicting the >: equilibrium composition of aqueous solutions, as opposed to using >: activity coefficients > >It was my understanding that it doesn't really matter if you use >activity coefficients if you are looking for equilibrium constant data >because the Keq's are all measured from experiment anyway >Jeffrey N. Woodford The problem is that Keq is measured at some concentration, usually dilute, and is not accurate at higher (read "other") levels unless you know how the activities vary with concentration. How much error to expect also depends on concentration and can be very large, else we'd find pH's of -1 in concentrated acids or > 14 in bases. Jerry < DOC0002 Subject: Re: Ohmic Heating From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/03/29 Message-ID: <3lchef$75p@Sierra.onr.com> Newsgroups: sci.chem and there's also electrolysis to worry about -- you don't >want the rice cooker to blow up from a hydrogen-oxygen reaction! Alternating current should take care of this problem, The products would recombine at the electrodes. An induction coil can be used to limit current if you like your rice THAT salty (actually, I guess this is done electronically these days, but I'm an old dog). Jerry DOC0003 Subject: Re: Ohmic Heating From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/03/29 Message-ID: <3lce4r$5ti@Sierra.onr.com> Newsgroups: sci.chem Organization: Onramp Access, Inc. X-Newsreader: WinVN 0.91.6 > >>Not to mention cooking rice ;-). > >You might put some salt in the water the rice is in. Of >course, ohmic heating might take a little more time that way ];) When I was a kid I made a hot dog cooker from two nails, a board and a line cord. The apparatus worked fine for dogs, but did nothing to a raw chicken leg. You've heard that they put too much salt in prepared food. Now if we raised the voltage.... Jerry DOC0004 Subject: Re: Oxygen solubility Deuterium oxide? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/03/29 Message-ID: <3lcbvs$5ti@Sierra.onr.com> Newsgroups: sci.chem In article , schlyer@um.cc.umich.edu (B. Schlyer) says: > >Does anyone know the solubility of oxygen in deuterium oxide at room >temperature? Would one expect it to be signifigantly different from the air I have no data, but I would certainly think the solubilities would be about the same. If D2O had different mutual solubility coefficients with other substances, it wouldn't be so darned difficut so separate the two isomers. Jerry DOC0005 Subject: Re: glass reaction From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/01 Message-ID: <3liir9$n75@Sierra.onr.com> Newsgroups: sci.chem > >Does anyone know of a any chemicals that react with glass other than HF? Alkali hydroxides such as caustic soda (sodium hydroxide, lye, NaOH) react with glass, particularly when they are concentrated and hot. Fused alkalis will dissolve glass to give a material known as water glass, which used to be widely used in such applications as storing eggs (in WG solution), fire-proofing wood and making so-called "crystal gardens). Jerry DOC0006 Subject: Re: Nitro Cellulose From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/07 Message-ID: <3m4c8h$dt@Sierra.onr.com> Newsgroups: sci.chem >In article <3m43p3$ta@nntpserver.colpal.com>, Kevin_Flowers@ColPal.Com (Kevin Flowers) writes: >> >> Dose anyone have instructions for producing Nitro Cellulose (Flash Paper >It's much safer to purchase it from a magic or novelty store. Nitrocellulose is a high explosive. If you insist, the basic method is that same as that used to produce nitroglycerin except you use cellulose instead of glycerin. I don't advise making your own nitrocellulose and can't offer any instructions for obvious reasons. However, I do have experience in this area based on covert warfare techniques we worked on during the Viet Nam altercation and in the commercial manufacture of dynamite, etc. If you do make the stuff, the important thing is to get all the residual acid out. This means very very long washing with mild base - I mean several days, Nitrocellulose is not really a high explosive, but it can still be frightfully dangerous, especially under confinement. The material is also very sensitive to ignition by the tiniest spark because of its high surface area. Jerry DOC0007 Subject: Re: N2O From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/08 Message-ID: <3m5eu5$6bb@Sierra.onr.com> Newsgroups: sci.chem In article , efresco@Bush.edu (E.Fresco) says: > So my question is, does ammonium nitrate >decompose acording to NH4NO3-->N2O+2(H20) or according to >NH4NO3-->NH3+HNO3 or some other equasion? > -Zack The decomposition is complex, yielding mixture of nitrogen and nitrogen oxides including NO and NO2 which you most definitely do not want to inhale unless you're tired of breathing. Jerry DOC0008 Subject: Re: fingerprints:how?... From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/08 Message-ID: <3m6q9b$ss4@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3m5s50$3n@sct1.sct.fr>, bazoche@world-net.sct.fr (Stephane Bazoche) says: > >Do somebody could telll me how to reveal or detect fingerprints, >on a letter for example......??? Blow a little iodine vapor on the paper; the prints will appear as brown marks within a few seconds. Some detectives carry a small glass drying tube with a few iodine crystals held in by glass wool plugs. In cooler weather it helps to warm the tube slightly. Jerry < DOC0009 Subject: Re: help getting co2 from air From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/09 Message-ID: <3m7pua$krg@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3m1hgb$pva@newsbf02.news.aol.com>, odea56@aol.com (Odea56) says: > >Need to find a way to remove CO2 from a dry air stream. Could you use lime, perhaps to remove both H20 and CO2 from the air stream? Sodium hydroxide pellets might be used to remove the CO2 in conjunction with a cartridge to remove residual traces of water. Jerry DOC0010 Subject: Re: Common Ion Effect qesution From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/11 Message-ID: <3md09t$4ap@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3mbogi$i15@wn.aksi.net>, morpheus@aksi.net (Jeremy Dobrick) says: > >I'm a bit confused about the common ion effect. If I had some lead >chloride in a solution and then added lead sulfate what happens assuming >I have an excess of lead ions? I thought at first since lead chloride is >more soluable it would stay in solution and the lead sulfate would >precipitate out. On the other hand the sulfate has a solubility constant >that woould seem to dictate that the lead chloride would precipitate out >to allow enough of the sulfate to enter solution. Basically I am >confused, please help. > >Regards- Jeremy Look at it this way: Lead sulfate in not very soluble and it is less soluble in a saturated solution of lead chloride because the latter produces a lot of the common ion, lead. If the lead chloride is truly at the saturation point, throwing solid PbSO4 into the mix will cause only a very tiny amount of PbCL2 to precipitate because only a tiny amount of additional Pb++ can be contributed by the relatively insoluble sulfate. The solubility constant of PbSO4 may look "big" but that is a number with a negative exponent, which means it is very small and therefore incapable of having much common ion effect on compounds which have larger solubility constants, such as lead chloride. For any chemists reading this explanation I apologize for not introducing ideality and for directly comparing the magnitude of the ionization constants without allowing for the number of ions per mole of salt. Jerry DOC0011 Subject: Re: Question on dessicant From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/11 Message-ID: <3merj8$4cm@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3mee5e$ghl@omnifest.uwm.edu>, mlehman@omnifest.uwm.edu (Mark W. Lehman) says: > I am wondering if there is a diffreent substance or mixture that is >safe and easy to access that I could use as a dessicant instead of >the silica gel crystals I am currently using. Calcium chloride such as is used on the roads in some snowy areas is dirt cheap and is an excellent and voracious dessicant. Plaster of paris works fine but has a relatively small appetite for water. Both of these materials are recyclable in the oven. If POP is too expensive in the drugstore, just use some gypsum from gypsum dry-wall board after heating in an oven at 300 deg F or so. Magnesium sulfate (oven-dried epsom salts) will absorb a lot of water if you don't need extreme dryness. Jerry DOC0012 Subject: Re: Quick question on water From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/11 Message-ID: <3mevr7$4cm@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <0098EBAC.1F8E747F@netins.net>, rheldt@netins.net (Ryan Heldt - Legend Software) says: > >Hi, >I am a high-school chemistry stundent that is doing >a small project. > >How much energy (in joules or KJ) is required to >decompose 1 liter water into H gas and O gas: > >2H O ----> 2H + O > 2 2 2 > It takes about 58 (57.8) kcal to dissociate a mole of gaseous water at 0 deg C. We old timey chemists talk in calories and kilocalories. A calorie (thermochemical) is 4.184 Joules. Jerry DOC0013 Subject: Re: Quick question on water From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/11 Message-ID: <3mf14r$4cm@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3mevr7$4cm@geraldo.cc.utexas.edu>, glhurst@onr.com (Gerald L. Hurst) says: >> >It takes about 58 (57.8) kcal to dissociate a mole of gaseous water at 0 >deg C. We old timey chemists talk in calories and kilocalories. A calorie >(thermochemical) is 4.184 Joules. >Jerry > The original question was directed to a liter of water. If this means a liter of liquid water you need to add the molar heat of vaporization of water to give a total heat of dissociation of 68.3 kcal/mole, then multiply this figure by the number of moles in a liter (1000/18.02) and finally convert to kjoules by multiplying by 4.184kjoules/kcal. I should have said all this the first time. Jerry DOC0014 Subject: Re: Renaming SCI.CHEM; or "Are chemists snobs?" From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/11 Message-ID: <3mesgm$4cm@geraldo.cc.utexas.edu> Newsgroups: sci.chem >I have three daughters and I would like them to consider the net as a >resource, a source of information, alongside all the other sources of >information available. I can't speak for others, but I try to answer as many questions as possible, except for the "How do I make ..." questions related to explosives, poisons etc. The scientists I have known who were experienced and competent usually were very good about answering questions from youngsters or or older laymen. I suspect that high-nosed dismissal attitude is more prevelant among wannabes. Anyway, tell your daughters to ask away and I'll answer as well as I can. I have three boys, and one of them asked so many dumb questions that they finally gave him a Ph.D. in chemistry. Jerry < DOC0015 Subject: Re: Searchable Online Journal Databases? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/11 Message-ID: <3md64j$9c1@Sierra.onr.com> Newsgroups: sci.chem > >CAS offers an online service called STN International Please send me information on STN. Thanks DOC0016 Subject: Re: Solubility Of Gases From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/11 Message-ID: <3meu0m$4cm@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3mdbab$2k7f@news-s01.ny.us.ibm.net>, darryl2@ibm.net says: > >Why are gases generally more soluble in cold liquids? This seems counter >intuitive considering solid and liquid solutes are more soluble in >warm solvents. > >Is there a mathamatical relationship relating the fugacity of a >particular gas in a solvent to the temperature of that solvent? Try this qualitative viewpoint: When a solution is heated you would expect randomness to increase with increased molecular motion and it does increase through dissolution. Thus most solids are more soluble at higher temperatures. The same might be said of gases, but here vapor pressure and related fugacity effects are dominant. Picture dissolved gases a being liquids dissolved in other liquids and typically both the solute and the solvent liquids have a vapor pressure which will roughly double for every 10 degrees of increased temperature and thus the liquified gas will readily vaporize out. Since fugacity is roughly proportional to pressure, it is obvious that the fugacity of the dissolved material rises much more rapidly than that of the gas-phase material. Jerry Jerry DOC0017 Subject: Re: cyanide reagent From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/11 Message-ID: <3meiip$sul@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3mclau$l5k@news.umbc.edu>, jbloom@zeus.towson.edu (Joshua Bloomberg) says: > >What is the simplist QUALITATIVE test for the cyanide ion? >This test must discriminate between cyanate and formate >ions. > > -- jbloom@zeus.towson.edu > No joke. If you acidify the material, dangle a cigarett from your lips and breath very carefully, you'll get a strong metallic taste in your mouth. Careful though, a good whiff of HCN can knock you unconscious before you hit the ground. Jerry DOC0018 Subject: Re: Sarin From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/14 Message-ID: <3mme9s$323@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Ian Russell Ollmann says: > That incidents like the one that happened in >Japan haven't happened more often is evidence of the fact that current >measures to prevent such occurences are, in general, working. THESE >CONTROLS ARE NOT ON THE KNOWLEDGE SIDE OF THE PROBLEM OF PRODUCING >DANGEROUS/ILLEGAL MATERIALS, > For $5.00 in change you could photocopy entire articles about >the production of Sarin. Instead of restricting knowledge, the government >controls the supply of chemical precursors and equipment necessary to make >these agents. Without the precursors, these chemicals are either >impossible or much harder to produce. Without equipment, it cannot be done >safely. Safety is a must with gaseous toxins such as Sarin, otherwise the >chemist dies. Don't abuse the newbies. > > Ian Ollmann > Thank you very much for posting the composition of that very effective nerve toxin. Would you be kind enough to post a convenient method of synthesizing the material, preferably one which requires a minimum of sophisticated lab equipment. Maybe it's time we all dropped our stuffy attitudes toward poisons and destructive devices. I happen to be an expert on covert warfare, and am very knowledge in the area of home-made bombs, incendiaries, firearms, grenade launchers, etc. I have always refrained from posting answers to the numerous requests from "students" in alt.engr.explosives for instructions and formulations. Actually, most of this information is available to the public if they just take enough time to find it. Now that I see the light you have shed on the freedom of information concept, I feel I may have been guilty of intellectual snobbism in not encouraging young people in their pursuit knowledge. I suppose I could remedy the situation by changing my policy, and answering any question which has an answer that can be found by a literature search. On second thought maybe I better wait to see what other chemists' opinions might be on this general subject. Incidently, Safety is seldom foremost in the minds of my young knowledge seekers Jerry DOC0019 Subject: Re: Picrates From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/15 Message-ID: <3mp478$r73@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3mo8ip$4pm@usenet.ucs.indiana.edu>, jverburg@ucs.indiana.edu (john verburg) says: > >EdKChem (edkchem@aol.com) wrote: >: >Is there danger to using a saturated solution of picric acid as a method >: of >: >preparing derivatives of primary and secondary amine compounds. How >: stable >: >is the picric acid with respect to these types of reactions? > >: >Howell Cobb >: >cobb@cpsc.ucalgary.ca > >: Are you mad? There are safer reagents in any decent Organic text. As for >: stablity: IT ISN'T! Picric acid is inherently unstable and can explode >: on heating or by percussion. See Merck Index. > > I used to work for the safty office at The University of Illinois >(Chicago, Il). We used to pick up picric acid all the time. Of course it >was NEVER dry. Picric acid is unpredictable though. I heard some "old >boys" stories about it's disposal, way back when. They used to just shoot >it in a field with a high power rifle. Sometimes, it wouldn't explode. >Then they had picric acid spilled all over the place. Picric acid in water >is somewhat stable, but like I said unpredictable. If I had a choice, I >would look for another alternative. >JVERBURG As explosives go, picric acid is relatively benign. It is a bit more sensitive to impact initiation than TNT, which means it's relatively insensitive. A 30-06 rifle bullet will not cause it to explode in the unconfined state. It is not overly sensitive to heat, and has, in fact, been used as a cast bomb filler (Japan, WWII). The stuff was around for over a hundred years before the French realized it could be used in war. Heavy metal salts of the acid are another thing entirely and should be avoided. Even the ammonium salt (explosive D) has a red form which is dangerous. I would not try shooting the material with a blasting cap as a means of disposal, but initiation with a primer would be O.K. Most explosives can be disposed of easily by burning them in moderatley thin layers on a pilr of loose straw or newspaper (from a distance, of course). Picric acid can be destroyed by dissolving it in 25X its weight of a solution made from 1 part NaOH and 21 parts of Na2S.9H2O. The reaction evolves some H2S and NH3. I have no data, but I would be careful in working with concentrated solutions of picric acid (e.g. in warm acetone). I suspect that such liquids may be susceptible to the LVD phenomenon in glassware or other materials with high sound conduction velocities, e.g. hard materials. Jerry DOC0020 Subject: Re: Toothpaste & OJ From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/15 Message-ID: <3mpcqu$r73@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , "Eric J. Smith" says: > >Tonight over dinner, a friend asked me if I knew why orange juice tastes >so bad when you drink it right after brushing your teeth... I started >thinking and came up with the theory that the fluoride from the toothpaste >(either from NaF or that phosphate compound that I can't recall at the >moment) was pulling a proton from one of the acids in the juice resulting >in a small but bitter concentration of HF in your mouth. > >Does anyone know the real reason that this happens? > I'll take a bash at this question: As you know, taste is primarily a matter of smell. You can smell things from either the outside or from inside via the mouth and there is, a difference. That's why coffee never tastes as good as it smells. Now some of the neurons in the nose are sort of general purpose and some of them are specific to certain compounds. There is a body of theory which suggests that the selective ones react to specific vibration rates of the odor molecules so that chemically different things may have similar smells if the "vibes" are the same. Anyway, when the sensors are exposed to strong odors a temporary sensory fatigue sets in and, depending on the source of the odor, some but not all of the sensors temporarily deaden. Under these circumstances other aromas and tastes will be changed if they are complex in nature and contain species similar to the ones that stultified the sensors. I suggest that the aroma of strongly flavored tooth paste from inside the mouth does, in fact, anaesthetize some of the sensory nodes. Jerry DOC0021 Subject: Re: help: What is definition of Binding Energy? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/15 Message-ID: <3mp6hf$r73@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , jensen@halcyon.com (MattJensen) says: > >(I don't know if this group helps out with homework questions; >please direct me elsewhere if you don't. Thanks!) > >My friend's Chem 101 homework has a problem as follows: > "If the average binding energy per nucleon of two reactants is >greater than that of the product, then energy will be (a) released, >or (b) absorbed ?" > >It seems a little confusing because a thing has negative-balue >Binding Energy if it is stable, right? So does "greater" mean a >larger negative number or a number closer to positive (i.e., -3 >compared to -10?). What is the conventional meaning here, if there >is one? > >I know very little about Chemistry, and we hope to get a clear >understanding of this before her first test. Thanks a lot!!! > >- Matt Matt, the term "greater" means more positive. This can be really confusing because many of us chemists say things like "aluminum chloride has a very high heat of formation," which means chlorine and and aluminum mixtures lose a lot of heat when they react and that the energy (actually enthalpy) of formation is very negative and that the product thus has less energy and is relatively stable. In your friends nuclear binding case, the question is formally written and she has every right to interpret it literally, especially in light of the fact that by your teacher's convention more negative means more stable. Anyway -3 is definitely greater than -10 and any nuclear reaction going from -3 to -10 (you fill in the units) is going to yield energy and presumably give more stable products. In the case of chemical, rather than nuclear bonding some tables list what is known as "dissociation energies," which are the reverse of bond energies and are thus positive numbers. With regard to whether this forum is appropriate for homework inquiries, let's just say that opinions differ . You're more likely to get e-mail replies rather than an open posting in most cases. Jerry DOC0022 Subject: Re: CAN ANYONE IDENTIFY THIS CHEMICAL: C_3 H_8 (NO_3)_3 From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/16 Message-ID: <3mqfio$qmc@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3mpv7s$6pf@desiree.teleport.com>, bobg@teleport.com (Robert Greer) says: >Refrigeration greatly reduces nitroglycerine's sensitivity to shock. >*Much* safer when cold. > That's true up to a point. Freezing the stuff (glycerol trinitrate) is very dangerous. Even worse is thawing the stuff back out - as in thawing frozen dynamite. Powder companies (read "explosives companies) generally used a mixture of NG and EGDN (ethyleneglycol dinitrate), to lower the freezing point of dynamites and blasting gelatins in case of use in cold climates. BTW, the original message in this thread is obviously a put-on. The poster got the formula wrong - it's a bit long on hydrogens. Jerry DOC0023 Subject: Re: CHEMICAL ENGINEERING From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/16 Message-ID: <3mqg9c$qmc@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3mpsbs$imp@classic.iinet.com.au>, madams@iinet.net.au (maryvonne adams) says: > > HAS ANYONE DONE OR IS DOING THE CHEMICAL ENGINEERING OR WHO CAN > OFFER SOME GOOD ADVICE TO A HIGH SCHOOL STUDENT WHO WANTS TO TAKE > THIS COURSE AT UNIVERSITY AND WANTS ADVICE ON SUBJECTS TO DO IN > YRS 11 AND 12 OR SOME SOUND ADVICE ON ANY ASPECT OF IT. > IT WILL BE VERY APPRIECIATED. THANKYOU > A.A. > When you say "high school" are you referring to an Oberreal Schule or Gymnasium or an American type high school? I guess in any case you want to be shure to study all the math (calculus and differential equations), chemistry and physics possible. If you're planning to attend an American University try to learn to use the English language well, even if it is your native tongue. Bad grammar causes a lot of grief here even for graduate students. Jerry < DOC0024 Subject: Re: Question on dessicant From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/16 Message-ID: <3mqgn9$qmc@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3mp36l$1mu@buffnet2.buffnet.net>, krieder@buffnet.net (Kurt Rieder) says: > >You won't find a much better dessicant than quick lime (calcium hydroxide), >but it's messey and not worth regenerating... so throw it away. The same >is true of many of the hygroscopic salts... messey. Really does depend >on what you are doing. > I think you mean calcium oxide. What do you mean "messy"? are you referring to the fact that it is usually in powder form? Neither the oxide nor the hydroxide is hygroscopic and the latter is not a dessicant. Jerry DOC0025 Subject: Re: Question on dessicant From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/16 Message-ID: <3ms7lq$r3k@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , pbedwort@juliet.caltech.edu (Pete Bedworth) says: > >JERRY, >If calcium oxide isn't hygroscopic what, pray tell, is your definition of >hygroscopic? > >I think you may have meant deliquescent. > >PVB You're quite right. I was thinking about the "messy" part and meant "deliquescent." I was pointing out that CaO (but not Ca(OH)2) is a drying agent, and, of course it has to be hygroscopic. There are hard-fired varieties of CaO which are not hygroscopic, but that is incidental to my mistake. Sorry about that. I think Nigel Seeley was right when he suggested that the original post was intended to say "calcium chloride." We once built a plant which ground and packaged ammonium nitrate formulations. Initially we had no humidity control, so decisions to run or not to run were based on the appearance of spilled AN powder. If there were pools of liquid, we knew RH was above about 60% and it was no-go. A friend in a similar business located himself in the Reno area and could make crisp product all year round. Jerry DOC0026 Subject: Re: Vinegar and Acetic Acid From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/18 Message-ID: <3n11di$53b@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3n0t5u$3l2@geraldo.cc.utexas.edu>, JoshuaL25@mail.utexas.edu (Joshua L. Konkle) says: > >Ok....vinegar that is 5% acetic acid by weight. What, without knowing the density of the solution would the >molar value be. I don't think you can get it. Anyway, what is the standard molar concentration for a vinegar solution. >I am presuming it to be 1.0M. ??? > > Sincerely, >Hook 'em Horns! \________/----\________/ >Joshua L. Konkle U\ /U > U U \ / TTTTT >Chemical Engineering U U (__) T >University of Texas at Austin UU T The specific gravity of 5% acetic acid @ 20 deg C is 1.007. The 6% acid is 1.0 normal. Commercial acetic acid runs from 4 to 9%, so if your into pickling, it's good to comparison shop for maximum $/eq :) Jerry DOC0027 Subject: Re: help with g92 calculations. From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/18 Message-ID: <3n14u9$53b@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3muc0e$drc@hermes.louisville.edu>, d0gao001@homer.louisville.edu (Daquan Gao) says: > >Hello everyone: > >I need to know how to do calculations for the following problem. >Given the reaction: H2O + NH4(+)---> NH4(+).H2O >How can I calculate the change of enthalpy from the change(or variation ) of >the total energy? > >Can anyone mail me the input file for this? >I am rather new in using g92. This is for a presentation. > >Thank you in advance. > I don't know what g92 is, but if your talking about a reaction going on in aqueous solution, it seems to me that the enthalpy and energy changes would be the same since there isn't likely to be much of a volume change. If this is a case of a salt dissolving, I suppose there'd be a tiny PV change (negative), but that's calculable more or less if you have an anion you can ignore. Maybe I'm missing the big picture. If so, will somebody please straighten me out? Jerry >D. Gao > >gao01@xray3.chem.louisville.edu > DOC0028 Subject: Re: nalgene tubing rupture From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/18 Message-ID: <3n14fd$53b@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.chem.labware In article <63785.bmoulton@shark.stmarys.ca>, "Brian Moulton" says. > > >...My stills are all connected in series by 5/16" ID Nalgene Premium Tubing (autoclavable, non-toxic, LAB/FDA/USP VI grade) - standard Nalgene >tubing. The water is filtered first through a Cuno cold water filter to >remove any dirt/rust. All of the tubes are secured to the condensers with >'O' clamps. > >... The split was 2-3" long along the length of the tubing about half way >between the tap and the still (2' from both). I replaced all of the >tubing on the system with new tubing and replaced the filter. > >... This past weekend the same problem occurred.... Again, there was a >cut along the length of the tubing measuring almost 3", half way between >the filter tap and the first condenser. > From your description it appears that you are running a number of condenser jackets in series and that you have had two ruptures upstream before the first unit. I would suggest that you have a big pressure drop across this extended system and it is rupturing in the section with the highest continuous pressure - perhaps 40 psi or more. Using stronger (reinforced) tubing or copper tubing upstream might help. It would be interesting to put a pressure gauge on a T in the inlet line for a peek at the pressure. Jerry DOC0029 Subject: Re: Mercurous Perchlorate From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/20 Message-ID: <3n4q61$gvq@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Brent Hamstra says: > >On Wed, 19 Apr 1995, Jerry Patrick Gordon wrote: > >> Does anyone out there have a MSDS sheet on mercurous perchlorate? Apparently > >Metal perchlorates in general are potentially unstable chemicals. >Unfortunately this instability is highly unpredictable. I don't know about mercurous perchlorate, but there have been at least two reports of supposedly pure aqueous silver perchlorate exploding while being stirred. No proposed mechanism or equation was suggested to explain the occurences in the apparent absence of fuel materials. If the silver salt is truly dangerous, I wouldn't trust the Hg2 salt. Jerry DOC0030 Subject: Re: Cyanogenbromide (BrCN) From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/25 Message-ID: <3ni73j$6pq@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3ngsk4$9fn@auntie.bbcnc.org.uk>, tilbrook@chem.surrey.ac.uk (David A. Tilbrook) says: > >In article <3n8bbb$1lf@doboj.cca.vu.nl>, vinkers@gallium.chem.vu.nl >says... >> >>How dangerous is this compound ? >>Sounds quite toxic IMO! >> > Depends very much on jusy how much you are using of it. The most >dangerous part of it's use that I encounter is actually weighing it out. >(We use it for cyanation to produce cyanate ester materials.) > >The vapour pressure is quite low so inhalation is not much of a risk. you >should still observe full cyanide safety procedures though _ double >gloving, basic bath available for immediate neutralisation of contaminated >materials, first aider and backup in attendance with cyanide antidote and >breathing apparatus etc. etc......Oh yes and avoid acids!!! It's the >possiblity of HCN generation that's really dodgy. > >Have fun! > >David Tilbrook > ************************************************************** >David Tilbrook |tilbrook@chem.surrey.ac.uk >Polymer Group, Chemistry Dept. |Tel: 1 44 1483 300 800 x 9591 >University of Surrey, Guildford, |Tel: 1 44 1483 259 951 (direct) >Surrey, GU2 5XH, UK. |Fax: 1 44 1483 259 514 >************************************************************************ > HANG ON! I believe you're writing about a cyanide salt, not cyanogen bromide. The latter IS volatile, and a whiff of the stuff can knock you off your feet - no acid needed. I'm sure you know better, but were thinking about the usual precautions we chemists take when working with KCN, etc. BTW, I once got a whiff of a cyanogen halide that blacked me out on my feet. Jerry DOC0031 Subject: Re: oxidation-reduction reactions From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/04/26 Message-ID: <3nm0do$hb8@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , all@stpauls.dungeon.com (Andrew Byfield) says: If H2SO did exist then sulfur would have an oxidation state of 6 so as >to give the necessary -2 "charge" to balance the two hydrogens which are in >the +1 oxidation state. >************************************************************************* *** >Andrew Byfield, student and international explorer. >"Life is a tale told by an idiot, full of sound and fury, >signifying nothing." (W. Shakespeare) >************************************************************************* *** IF H2SO did exist, it might be looked at as an analogue of H2O2, in which case we would assign an oxidation state of -1 to the sulfur. I'm sure you knew this and meant to refer to H2SO4 as having sulfur in the + 6 oxidation state. Jerry DOC0032 Subject: Re: 1Ammoniun Nitrate From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/08 Message-ID: <3ok4ug$5qv@geraldo.cc.utexas.edu> Newsgroups: sci.chem > In article , shnst+@pitt.edu (Captain Entropy) says in re ammonium nitrate: > >I believe it is bagged & shipped as wax-coated pellets; this is the type >of material which caused the 1947 Texas City, TX, disaster. > AN is not coated with wax unless it is classified as a nitro-carbo-nitrate (blasting agent). The prills are usually porous and would happily soak up molten wax to create a form of ANFO. Unfortunately for the blasting industry, such mixtures exhibit very little water resistance. The material in the Texas City disaster is believed to have been contaminated by some extraneous oil. It may come as a surprise to some, but anfo does not support combustion well in moderate quantities. Jerry DOC0033 Subject: Re: 1Ammoniun Nitrate From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/08 Message-ID: <3ok4fe$5qv@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , shnst+@pitt.edu (Captain Entropy) says: > > >> >> Both were huge bulk stores which were ignited by other sources (fires, >> >> I mean). If I remember rightly, the Gulf Coast one was in a ship. > >I believe this ignited from compression, just as pressure in large coal & >slate heaps leads to a rise in temperature and occasional ignition. I don't understand how static pressure (as opposed to adiabatic compression) can cause heat. It seems to me that a large coal heap might undergo spontaneous heating from slow oxidation, but I doubt that AN/oil mix would react under similar conditions unless the oil was unsaturated. Jerry DOC0034 Subject: Re: Geometry Q in sci.chem? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/08 Message-ID: <3ok58u$5qv@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.math In article <3oeeti$ic1@senator-bedfellow.MIT.EDU>, tjs@slipknot.mit.edu (Toby J. Sommer) says: > >I need to drill a hole as close as possible to dead center in a 12" >pie plate. Anybody know how to construct a true diameter or otherwise >find dead center of a circular disk? Since this is a real lab/shop >problem, drawing tangents and using points out at infinity won't be >too practical; on the other hand, I can use more than straightedge and >compass. Balance the plate on a nail point and tap it with a rubber hammer to leave an indentation (unless it's a glass plate). Jerry DOC0035 Subject: Re: h202 as oxidising agent From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/08 Message-ID: <3ollrv$rga@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3oilg0$7uv@news.annex.com>, alchmist@annex.com (John Milligan) says: >> >This is valid for your reaction since the ammonium ion creates a basic >medium. Actually, the ammonium ion is slightly acidic, i.e. it wields a proton rather than accepting one. Jerry DOC0036 Subject: Re: 1Ammoniun Nitrate From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/09 Message-ID: <3onuu0$bif@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , emilsson@aries.scs.uiuc.edu (Tryggvi Emilsson) says: > >glhurst@onr.com (Gerald L. Hurst) writes: > > >>In article , >>shnst+@pitt.edu (Captain Entropy) says: >>> >>> >>>> >> Both were huge bulk stores which were ignited by other sources >>(fires, >>>> >> I mean). If I remember rightly, the Gulf Coast one was in a ship. >>>I believe this ignited from compression, just as pressure in large coal & >>>slate heaps leads to a rise in temperature and occasional ignition. > > I once saw a TV program on the Texas City disaster,and if my recolection is >right, this is what happened: [TV show description omitted] > There is,therefore,no need to speculate on the cause of the explosion. > >T.Emilsson >U.of Illinois > The fact that the "answer" to this question was presented on TV will hardly satisfy the experts who have looked into this matter and reached other uncertain conclusions. Many of us do not really consider the tube as an authority on much of anything. There were numerous facts brought out in the litigation which followed the explosion that lead to other conclusions regarding the mechanism of the explosive initiation, including the fact that the prills were wax-coated with almost precisely the right amount of paraffin to reach maximum sensitivity. Also, the material was probably shipped hot and in bag material which is also known to react exothermically with AN at the shipping temperature. Furthermore, there had been a couple of fires in the rail cars which carried the product to the ship. There have, of course, been other AN explosions which are known to have been caused by fire. The last one I remember originated from a fire in an AN manufacturing plant in Oklahoma. The material is said to have exploded in the fire after contact with melted rubber belting. Jerry < DOC0037 Subject: Re: Please help: Brownian Motion From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/09 Message-ID: <3omi65$ggl@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3oj7si$oai@umbc8.umbc.edu>, mark@umbc.edu (Mark Meytin) says: > >Hi, >I am looking for a way to prove Brownian motion - the chaotic >movement of colloidal particles. What I need to do is to put something >under a microscope so that you could see particles moving. > If you want to see Brownian motion in action, use a dark-field microscope and observe the smaller bright points of debris in whatever kind of not very pure water. An interesting subject would be a droplet of your own blood. At oil-immersion magnifications, you will be able to see the infamous somatids of Dr. Naessens as little bright stars doing the Brownian Jig. We Jury-rigged a conventional medical 'scope for dark-field and it worked fine. Jerry DOC0038 Subject: Re: diesel fuel/kerosene From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/09 Message-ID: <3omqhb$o6v@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , fusina@ecf.toronto.edu (FUSINA GIOVANNI) says: > > hello! > >does anybody know what the chemical composition (molecular formula) of >diesel fuel is? Do you know where I could find thermochemical data for it? >What about kerosene? > >Thank you in advance for your replies.... > >--Giovanni > You can always get an argument on this subject, but both kerosene and the most common #2 diesel fuel are mixtures of mostly aliphatic hydrocarbons having a flashpoint above 120 deg F. The compositions would comprise mainly hydrocarbons in the C-10 to C-16 range. Depending on where you look you may find the minimum flaspoint of kerosene listed at 100 or 150 deg, more often the former. If you actually purchased and tested kerosene you'd probably get a flashpoint of 125-140. If you want thermochemical data you'll have to pick a particular brand and batch because the only consistent property you will be able to find is an approximate equivalence in the temperatures at which 10% increments distill. Then run a GC - mass spec to identify the many components and calculate with your fingers crossed and not too many decimal places. If all you want is heat of reaction in some kind of oxidation reaction, you can skip the analysis and just consider it as a midrange hydrocarbon like dodecane. Kerosene is cleaner than diesel, usually having far less sulfur and being water clear. They even make odorless kerosene for use in, for instance, special ANFO for blasting minerals intended as supplements in cattle food. Kerosene or fuel oil for ANFO must have a flashpoint of 140 deg f or greater. If it is intended for kerosene heaters, it is given a "1-K" rating to guarantee low sulfur. Fuel oil formulations are changed for periods of cold weather. Jerry DOC0039 Subject: Re: keeping CO2 liquid ? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/09 Message-ID: <3omhae$ggl@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.bio,sci.misc,sci.physics,sci.polymers,sci.research In article <1995May8.144604.8846@njitgw.njit.edu>, bxa3446@hertz.njit.edu (bart adams me stnt) says: > > >Are there any substances that lower the solidification point of CO2 ? >(in the same way that salt does the trick with water) >If you know of any, or know some literature where I could find some clue, >please let me know, > >My e-mail : bxa3446@hertz.njit.edu > >Thanks a lot. > >Bart Adams. > > >Many things are soluble in CO2 and would consequently lower the freezing point. My old Audrieth and Kleinberg "Non-Aqueous Solvents" doesn't mention the subject, but there's been a lot of non-aqueous fluid under the bridge since it was written. There's been a lot more work done in this area in recent decades since they found that caffeine could be extracted and emulsions could be made with the stuff. If you're not up to a Chem Abstracts search, I'd simply look for a newer book with a similar title in the chem library or section. CO2 will behave like water in the sense that it will have a molal freezing point depression constant. Jerry DOC0040 Subject: Re: A: How to glue polyethylene or polypropylene From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/17 Message-ID: <3pdui2$g8n@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3pdnb0$dhp@saba.info.ucla.edu>, Flint Smith says: > >Bernard Morey wrote: >>On Mon, 8 May 1995, William R. Penrose wrote: >> >>> In article <1995May6.031747.19253@sequent.com> stuartf@sequent.com (Stuart Friedberg) writes: >>> >>> >Q: How can you glue polyethylene or polyproplyene? >>> >>> ... hot-melt glue ... > >>I'm sure you can't have been trying to join PE or polyprop. A glue gun >>just won't work -- I've tried it. It may _sort of_ work if there is no >>stress on the join, but the slightest movement and ... boing! > >Being a destructive guy by nature, I have pulled the colored cups from the >bottoms of 2-liter PE(?) soda bottles. It takes a fair amount of effort, and >"boing" doesn't describe it. The glue appears to be (color, texture, >softness, threads between glue-points) hot melt glue and is very effective. >Maybe your quality control wasn't up to snuff. Maybe a different glue >formula or temperature would account for the difference. > >Flint Smith flint@uclaue.mbi.ucla.edu > Soda pop bottles are a PVC laminate having, I've read, about 5 layers. PVC, of course can be readily glued with PVC dissolved in a solvent or by solvent alone. Nylon and polyester are difficult to glue, but hot-melt works OK. Polyolefins can be glued with hot-melt too, perhaps because the chemical similarity of the plastic and the glue (polyethylene + EVA) lead to melting point depression of the former from blending at the interface. That's a guess, folks. Jerry DOC0041 Subject: Re: ANSWER TO NOT SO HARD CHEMISTRY A-LEVEL QUESTION.HELP!!!! From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/17 Message-ID: <3pdoe0$bch@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Lev Gorenstein says: > >No, not necessarily! The RDS may include intermediates, that do not >enter in the overal reaction equation and do not enter the kinetic rate >law. Those intermediates concentrations are derived from the other >mechanistical equations as functions of other konstants and reactants >concentrations. They then are plugged in the RDS kinetic equation >and produce the overall rate law. That's where you sum up the powers >and get the order. If you sum up the coefficients in the RDS, more >likely than not you will get different result (and it'll be wrong). > Please refer to my query posted in response to similar material by Joseph S. Merola. Jerry DOC0042 Subject: Re: ANSWER TO NOT SO HARD CHEMISTRY A-LEVEL QUESTION.HELP!!!! From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/17 Message-ID: <3pdn74$bch@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , jmerola@vt.edu (Joseph S. Merola) says: > >Well, there is still only one rate determining step: it is the slow >step in the reaction which determines the overall kinetics of the >system. I think this still has a lot to do with the original >question. For example, you may have a reaction in which >A + B ---> C, but the rate determining step in the >reaction may involve intermediates X, Y, and Z. An overall rate >law is written in terms of the species in the balanced equation, not >based on the intermediates in the rate determining step. > > Sure, that's how the overall rate law is written, but if you want to write a meaningful RDS you have to do it in terms of X, Y and Z. I fail to understand how one set of reactions in, say, a series of second order reactions of similar rate could be chosen as the RDS when such a reaction would in no way "determine" the overall rate, but would simply exert slightly more influence thereon than the others do. All of my postings on this matter really amount to the simple proposition that if you tell me that the rate law for a given reaction is no more complicated than the product of a few concentrations individually raised to some powers, then I can probably deduce the coefficients in the corresponding reaction. I certainly understand that you can show a rate law equation of some other form, which will not permit such an inference. I make no claims to be particularly knowledgeable in the area of kinetics and I am willing to learn from wiser heads. If you can give me an example contrary to my proposition, I'll happily assimilate it into my old gray noggin. Of course, I've often seen relatively slow reactions in a longer sequence referred to as the "rate determining step," but I always assumed this was a more or less colloquial use of a phrase more aptly applied to cases where really large differences were present in the rates. Jerry > >------------------------------------------------------------------------- ----- > Joseph S. Merola > Director of Graduate Education > Department of Chemistry Internet: JMEROLA@VT.EDU > Virginia Tech Voice : (703) 231-4510 > Blacksburg VA 24061-0212 FAX : (703) 231-3255 > >------------------------------------------------------------------------- ----- DOC0043 Subject: Re: ANSWER TO NOT SO HARD CHEMISTRY A-LEVEL QUESTION.HELP!!!! From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/17 Message-ID: <3pdd16$5ss@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , jmerola@vt.edu (Joseph S. Merola) says: > >In Article <3pbvgc$bge@geraldo.cc.utexas.edu>, glhurst@onr.com (Gerald L. >Hurst) wrote: >>In article , >>Lev Gorenstein says: > > > >>>Not exactly correct. The order of the reaction is the sum of powers, in >>>which the concentrations of reactants enter in the RATE LAW equation for >>>the reaction. It is not the sum of coefficients in the RDS equation. >>>When you have the rate law: > > > x y z >>> rate = k*[A] *[B] *[C]*...., > > >>>You can then say: Order = x+y+z. >>> >>>But doesn't the rate law equation derive from the corresponding RDS >>equation which would be: >> >> x[A] + y[B] + z[C] ... >> >>in which the sum of the coefficients is equal to the sum of the exponents >>in said rate law equation. > > >No, because the rate law can be a composite of all steps that lead >up to the rate determining step. There may be several equilibra that >precede the rate determining step and will contribute terms to the >overall rate law. > OK, but if there are several rate determining steps in a reaction, can you then write the rate law equation as the simple product of the concentrations raised to the respective coefficients as was done in the SPECIFIC example above which I used for my derivation? If the supposed RDS is not slow enough to establish the overall rate of reaction then there is simply no RDS for that sequence. You are certainly right that a reaction sequence may have numerous steps which influence the overall rate, but that fact has little to do with the original subject of this discussion in my often flawed opinion. Jerry DOC0044 Subject: Re: ANSWER TO NOT SO HARD CHEMISTRY A-LEVEL QUESTION.HELP!!!! From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/17 Message-ID: <3pbvgc$bge@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Lev Gorenstein says: > >Not exactly correct. The order of the reaction is the sum of powers, in >which the concentrations of reactants enter in the RATE LAW equation for >the reaction. It is not the sum of coefficients in the RDS equation. >When you have the rate law: > > x y z > rate = k*[A] *[B] *[C]*...., > >You can then say: Order = x+y+z. > >But doesn't the rate law equation derive from the corresponding RDS equation which would be: x[A] + y[B] + z[C] ... in which the sum of the coefficients is equal to the sum of the exponents in said rate law equation. We don't know how many angels can dance on the head of a pin, but the number is probably the same no matter how you calculate it. Jerry DOC0045 Subject: Re: MISSING USGS RECORDS OF 04/19/95 From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/17 Message-ID: <3pdve4$g8n@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3pdlof$r6r@mack.rt66.com>, diamond@rt66.com (Russell Stewart) says: > > >Furthermore, as a friend pointed out to me, there were cars in the >parking lot that had the gas in their tanks set off by the explosion. >This would easily account for reports of multiple explosions. > Only in the movies. Although gasoline-air detonations are possible under suitable circumstances, they are unlikely to occur in real life car fires, except for little bangs under the hood or in more or less empty tanks. Explosions caused by confined gasoline-air, as inside a room are much more common, but hardly likely to give much of a seismic pulse as compared to a couple of tons of condensed explosive. In real life explosions of such things as ANFO, C-4 and dynamite, etc., there is very littl flash and smoke. Hollywood adds petroleum products to their explosions so they will burn in great fireballs and generate clouds of carbon smoke. Jerry DOC0046 Subject: Re: Rust? stains on concrete From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/17 Message-ID: <3pbt1j$bge@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3pb192$9vq@luggage.rednet.co.uk>, Bryan Murphy says: > >Pardon my arrogance, but aren't alkalis caustic Acids, bases and comments can be caustic, each in its own way. The term "caustic" is sometimes used to denote strong bases as in "caustic soda" or "caustic potash," but it is also used in the broader sense of "corrosive." Jerry DOC0047 Subject: Re: Tagging ammonium nitrate (or something like that) From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/17 Message-ID: <3pbucu$bge@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3paiuh$f0@gap.cco.caltech.edu>, et@liquefy.ugcs.caltech.edu (Ernest S. Tomlinson) says: > >On the way to school this morning I caught the last half of a story >on NPR, about a proposal (by who, I didn't catch--probably some Senator >Foghorn duckspeaker hit upon the idea) to tag all ammonium nitrate >produced in the U.S. so that, if it were used in a bomb, it could be >traced. > >The word (not a word, a revolting neologism) "taggant" was tossed >around in the news-story. Now I doubt that the word "taggant" exists, >and if it does, it shouldn't; but it seemed to refer to some special, >unusual sort of marker that isn't manufactured in the U.S. NH4NO3 >would be, I guess, adulterated with these "taggants". > >My first reaction to this was "Jesus Christ! Are they gonna 'tag' >fuel oil as well??" But I'm reserving judgement until I hear more >than half a news-story. Anyone have any info on this? > The move to force manufacturers to tag explosives and precursor chemicals is decades old. The chief proponents include the BATF and FBI. Explosive packaging is presently labeled with enough code to identify the source, date and shift of manufacture, but of course such markers are destroyed when the materials are shot. Various binary code schemes have been proposed, but the frontrunner system is apparently one using tiny particles made of laminates of colored layers representing bits or bytes of information. The problem, of course, is that the addition of such materials may sensitize or otherwise contaminate materials and create a potential bookkeeping nightmare. Also, there is the problem of in-plant cross-contamination which would require the otherwise unnecessary step of thoroughly cleaning manufacturing machinery between batches. If the little particles are stable enough, we should wind up up to our necks in them after a few decades and they will be using "cross-contamination" as an argument in more trials than Judge Ito ever dreamed of. Jerry DOC0048 Subject: Re: sodium azide From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/17 Message-ID: <3pdpde$bch@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3pdl4d$shg@news.acns.nwu.edu>, cathryn@merle.acns.nwu.edu (Cathryn M. Majkowski) says: > > > >Hi, > >I was wondering if anyone has any information or knows where I could find >information about toxicity levels and sodium azide. I have some data on oral lethal >doses in men and women, but I can't seem to find any info on non-lethal doses. According to the Merck Index, "Some azides cause fall in blood pressure and inhibit cytochrome oxidase and other enzymes." You'll find this information under "lead azide." Only the hypertensive properties are mentioned under the sodium salt entry, probably by oversight rather than any specificity to the lead compound. Jerry DOC0049 Subject: Re: Lawsuit against fertilizer mfr (Okl city bombing) From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/18 Message-ID: <3pgb6v$rnp@geraldo.cc.utexas.edu> Newsgroups: misc.legal,sci.chem In article <3pg6m0$rmm@moe.cc.emory.edu>, lparker@larry.cc.emory.edu (Lloyd R. Parker) says: >: Consequently, if the >: fertilizer can easily be changed to lose it's bombing qualities while >: retaining all of it's fertilizing qualities AND the company reasonably >: foresaw the killings then there could be an argument for liability. >: >: --- > >Actually, a judge in California has allowed a gunshot victim to sue the >gun maker, the argument being that the gun maker should have reasonably >foreseen that the product was dangerous. Judges are likely to let people sue over most anything and let the trial sort out the mess; that is why we have the push in congress to limit frivolous lawsuits. I had a case once (consulting) in which a young man found some of those little firework torpedos with the non-PC in the parking lot of a bowling alley and stuffed them in his pocket. According to his complaint, he tossed the ball down the alley and at that moment his left pocket erupted causing him to dance around furiously and yank down his pants and receive burns to a portion of his anatomy where no man should suffer. So ... whom did he sue? The (Asian) company which had manufactured the butane cigaret lighter he happened to have in his pocket. The theory was that the bowling motion caused the flint wheel to turn, creating a spark which ignited a fuse on one of the fireworks. His attorney brought in a shave-tail engineer who testified in his deposition that the standard pocket lighter is unreasonably dangerous because there is no safety clutch or brake on the flint wheel and that the manufacturer should have foreseen that this omission constituted an unnecessary hazard. This case never went to trial, but settled for a ridiculously high amount to avoid the otherwise higher cost of defending the suit in court as is frequently the case with frivolous suits. I am currently aware of a pending case in which a woman shot herself in the leg with her major name brand (semi-)automatic pistol. Of course, the allegation is that the gun malfunctioned, despite the fact that it had been modified and repaired in jury-rig fashion. This is another case looking for a nuisance settlement. Or how about a case in which an explosion occured in a very small room containing 120 lbs of smokeless powder and thousands of primers. The explosion pushed a couple of walls a few inches only, but sent a fire ball through the house resulting in two burned and orphaned children. The family sued guess who? he manufacturer of the computer printer which was also in the room. Theory? The printer shorted, got very hot as a result and released an explosive aerosol as the plastic decomposed. The aerosol concentration increased until the lower explosive limit was reached and then boom! Absurd you say? Idiotic? Nope, both the plaintiff and defendant attorneys checked with local gunshops and national powder manufacturers and became convinced that "Gunpowder does not explode unless it is confined." It took the defendant's expert (me) a couple of years to convince the truly exceptionally intelligent team of defense lawyers and other experts that the propellant was the culprit, and this was first accomplished the night before the trial when I visited another expert in his apartment and put on a demonstration of the explosion of "unconfined powder," We videotaped the demo the second time around in such a way as to demonstrate both the pressure and fireball effects. The Jury (and our own lawyers), because of the press of time, saw the video tape in detail for the first time in the courtroom. We won the case, but it cost at least half a million to prepare and try it. Oops, shut him down - he's telling old war stories again -- Jerry DOC0050 Subject: Re: me on TV in Boston WCVB From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/18 Message-ID: <3pe5gm$g8n@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3pe1lq$3pn@dartvax.dartmouth.edu>, Archimedes.Plutonium@dartmouth.edu (Archimedes Plutonium) says: > the totality is a single atom. A single atom with many atoms >inside it. The space of atoms is the space of electrons. Our night sky >is merely the space of the 93rd and 94th electrons. The mass of >everything we see is just the mass of the 93rd and 94th electron. The >missing mass of the universe is the nucleus, but we will never see it >for it is in a atom node. Well, sure, everyone knows that the universe is an atom, but where do you get this 93rd and 94th electron business. The universe is clearly not merely any old atom, it is a technetium atom and therefore has only 43 electrons. This structure accounts for the instability and chaos in our world and the bad TV reception. Certainly, the scientific community is obtuse, as is obvious from their reluctance to accept a number of my theories. Maybe I should try TV. Jerry DOC0051 Subject: Re: Gallium Oxide From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/19 Message-ID: <3ph3eh$e6t@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , wpenrose@interaccess.com (William R. Penrose) says: > >In article <3p88sm$mri@msunews.cl.msu.edu> root@localhost.com (Phil Storm) writes: > > >> I've posted this a few times....but I was wondering if it is possible >> to seperate Ga(2)O(3) (gallium oxide) into Ga and O by electrolysis? Like >> by using Gallium oxide as the anode of electrolysis in an NaCl solution? > >Using aluminum oxide (same Group) as an analogy, my guess is that you won't >do it in aqueous solution. Al is made by high-temperature electrolysis of >aluminum oxide in a flux of molten cryolite, a mineral of some kind. > Seems to me that chlorine would be more likely at the anode than oxygen. Jerry DOC0052 Subject: Re: Lawsuit against fertilizer mfr (Okl city bombing) From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/19 Message-ID: <3piss8$bh9@geraldo.cc.utexas.edu> Newsgroups: misc.legal,sci.chem Article Segment 1 of 2 In article , cvxdrk@arco.com (David R. Kinney) says: > >In article , rcanders@nyx.cs.du.edu (Mr. >Nice Guy) wrote: > >There IS a process (patented some 20 years ago) for the addition of >ammonium phosphate to ammonium nitrate fertilizer that renders the >fertilizer ineffective as an explosive. Additional cost is minimal, but >ANY additional cost was deemed to be too much by the manufacturers. See >the Philadelphia Inquirer (5/19/95?) for a good profile of the patent >holders and their story. > The following is a copy of relevant material I posted in alt.engr.explosives and misc.legal: >>In article <3ph10u$lo@stratus.skypoint.net>, jlogajan@skypoint.com (John >>Logajan) says: >> >They just had on Jeraldo CNBC show an inventor of a 1962 patent process >>Apparently his process is to mix diammonium phosphate with the ammonium >>nitrate. > >>The question is, is it hard to extract the diammonium phosphate from >>the ammonium nitrate by some means, such as a differential soluability >>or other fairly simple chemical "cleansing"? > I believe the inventor you're referring to was an engineer named Samuel Porter and the patent was issued in 1968. Mr. Colbert was an engineer who later joined Mr. Porter and helped him pitch his idea of diluting AN with DAP, an already well-known fire retardent and fertilizer. It appears that similar mixtures were already in use, mainly overseas, where they use more DAP fertilizer than we do, perhaps because of our calcium phosphate technology based on work by the TVA with the calcium salts. Aqueous mixtures of AN/DAP are often found in home-gardener liqid fertilizers along with a potassium salt and some green dye. Presumably, this "prior art" interfered with broad coverage of the system in the Porter patent because the claim language vaguely alludes to the necessity of intimately mixing the materials by co-crystallization and/or what-have-you. Most of the tests of the mixtures were with fire, and the DAP did what it had long done for paper, etc - it retarded the fire. It might be pointed out that trying to burn ANFO isn't that easy anyway. In practice, when you light a bunch of paper under the stuff, it goes out nearly as soon as the paper has burned away. The explosive tests were conducted in two series: the first with #8 blasting caps, and the second with the same plus a two feet of 50 grain detonating cord cut into 2-inch pieces and taped around the cap. These initiators were used to set off about three-pound charges in half-gallon cylindrical ice-cream containers about 4" in diameter and 10" long. Rather than using witness plates, the Dautriche method or electronic instrumentation they relied on a "tell-tale" consisting of a fifteen foot length of detonating cord with one end contacting a piece of steel and the other terminating in a crimped #6 fuse cap. The fuse cap was inserted in the distal end of the charge with respect to the #8 detonator. From a series of shots using the above arrangement they obtained results which they classified as H.O. (high order), L.O. (low order) and N.D. (no detonation). The treated material was reported to show no results greater than L.O. and mostly N.D., while the "regular" ANFO gave H.O. results every time. It should be mentioned that the ANFO and the treated ANFO used in these experiments was not actually in the form of prills but rather a powder with about 30% passing through a 35 mesh screen. One might also note that the ammonium phosphate may actually have been the monobasic material because of the thermal loss of one ammonia group during hot processing steps. Please do not interpret my description of this work as either praise or criticism. I am supposed to be an expert in this field and that means that I must study the subject objectively and carefully before I form any firm opinions. I would, however, welcome any comments from those who do have thoughts on the matter DOC0053 Subject: Re: Lawsuit against fertilizer mfr (Okl city bombing) From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/19 Message-ID: <3piss8$bh9@geraldo.cc.utexas.edu> Article Segment 2 of 2 As to the question of whether or not one could readily separate the AN from the mixture, the answer is "Yes." It is a personal quirk of mine to hesitate in giving instructions that might lead a youngster to try something he shouldn't. Probably any young chemist reading this forum will instantly realize how very easy the separation would be, but it'll make me squint to see it in print. Jerry DOC0054 Subject: Re: Speed of combustion of gasoline From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/20 Message-ID: <3pjs5h$1d4@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <9505192144591.The_Win-D.loyl@delphi.com>, loyl@delphi.com (Loy Lawhon) says: > >I have been asked a question that I have no idea how to calculate: > >If a line of gasoline could be laid out for a mile without evaporating, and >you lit one end, how long would it take for the flame to travel the mile to >the other end? Can anyone help me, please? If the gasoline is unconfined and unassisted by external air currents, it will burn along at the pokey linear rate of a bit over one ft/sec. However, if it is in a reasonably large pipe and well mixed with a roughly stoichiometric amount of air, expect the combustion wave to transform into a detonation before it has travelled more than a few feet. The reaction should then cover the rest of the mile in under one second. I guess you could say the answer is more than an hour or less than a second. Jerry DOC0055 Subject: Re: Speed of combustion of gasoline From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/20 Message-ID: <3pjrk5$1d4@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <9505192144591.The_Win-D.loyl@delphi.com>, loyl@delphi.com (Loy Lawhon) says: > >I have been asked a question that I have no idea how to calculate: > >If a line of gasoline could be laid out for a mile without evaporating, and >you lit one end, how long would it take for the flame to travel the mile to >the other end? Can anyone help me, please? > >Gasoline vapor burns at a rate of a bit over one ft/sec unless you burn it in a pipe. In the confinement of a a pipe of sufficient diameter, you can expect a well-mixed gas-air mix near stoichiometry to shift into detonation mode after burning a few feet and the reaction can travel one mile in about one second. o DOC0056 Subject: Re: ANSWER TO NOT SO HARD CHEMISTRY A-LEVEL QUESTION.HELP!!!! From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/21 Message-ID: <3pme7f$cim@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3pl895$nc4@oban.cc.ic.ac.uk>, s.hogg@ic.ac.uk (Simon Hogg) says: > > >>OK, but if there are several rate determining steps in a reaction, can >you >>then write the rate law equation as the simple product of the >>concentrations raised to the respective coefficients as was done in the >>SPECIFIC example above which I used for my derivation? If the supposed >>RDS is not slow enough to establish the overall rate of reaction then >>there is simply no RDS for that sequence. You are certainly right that >a >>reaction sequence may have numerous steps which influence the overall >>rate, but that fact has little to do with the original subject of this >>discussion in my often flawed opinion. >> >>Jerry >> > >Surely ther is only one rate determinig step for a reaction?!?!?!? > >Simon > That was one of the poorly stated points I was trying to make. It seems to me that that if one has a reaction sequence with several steps that influence the overall rate to similar degrees, then there is no such thing as "THE RDS." Apparently this idea is either wrong or too semantically uncertain to be understood, or so I'm told. Sigh. Jerry DOC0057 Subject: Re: Glass From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/21 Message-ID: <3po5nf$7b5@geraldo.cc.utexas.edu> Newsgroups: sci.chem > >Most glass is just silicon dioxide. Whether it is crystalline or >amorphous glass. Some glass includes lead (e.g. lead crystal) and some >includes boron (e.g. borosilicate glass used in chemistry lab glassware >and Pyrex(tm) also, I think). You say you want chemical reactions. >Reactions involving what? The production of glass? > > Si + O2 --> SiO2 > >The other reactions (for borosilicate and lead crystal) may be found by >doing a little library work. Hey, you're going to confuse the student with an answer like that. Although SiO2 has a "glassy" or vitreous form it certainly is not true that "Most glass is just silicon dioxide." Typically, glass is made by dissolving metal oxides in SiO2, most commonly Na2O and CaO to produce common soda lime glass. Lead may be added to give a higher index of refraction and make "crystal" or boric oxide may be used to yield heat-resistant glass such as "Pyrex." Sometimes the composition of these mixtures is simply written in the form SiO2.xNa2O.yCaO..., but a teacher might well want you to show the product in terms of the silicates that are actually formed such as Na2SiO3, etc. Glass is not always made directly from oxides, but may start with other compounds such as silicates or borates or materials which form oxides on heating. It is believed that the first glass was produced by accident when primitive fires melted sand (SiO2) and ashes (carbonates) together, driving off CO2 to leave a mixture of oxides (silicates) in the embers. Of course, modern glass making is much more complicated than my simple explanation. Any encyclopedia will furnish a wealth of very interesting details. Jerry DOC0058 Subject: Re: Use of Perchloric acid in non-perchloric acid hood From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/21 Message-ID: <3pmfan$cim@geraldo.cc.utexas.edu> Newsgroups: sci.engr.chem,sci.chem In article , wpenrose@interaccess.com (William R. Penrose) says: >The problem comes when the perchloric acid condenses on the oils and other >organic crud that accumulates in hood ducts. The organic perchlorates will >detonate. Back in the good old days I ran a remote lab or three in which we worked with a lot of ammonium and sodium perchlorate as well as various nitrates on unfinished wooden benches. Ocassionally, to protect our hydes, we'd remove a table top and destroy it by burning. The nitrate impregnated tops burned with considerable vigor, but those containing a good dose of perchlorate salts were downright spectacular. We also had occasion to deliberately dope blocks of wood with certain inorganic chlorates in the name of covert warfare studies. These little items would explode on impact when tossed in the air or struck with a .22 rimfire bullet. Not all of us survived those days. Those of us who did are probably a lot more conservative today. Jerry DOC0059 Subject: Re: salt & ice. Cool beer question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/21 Message-ID: <3pob32$7b5@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3po6hr$at2@doc.jmu.edu>, connc@sunrise.cs.jmu.edu (charles conn ) says: > >A friend of mine told me that we should add rock salt to our >cooler filled with ice and beer bottles. He mentioned that this >would allow the beer to get colder, even to the point of ice >forming inside of the bottle sometimes. I was wondering why >this occurs? What chemically occurs to allow this to take place? >Does the salt raise the melting temperature? > The salt lowers the melting temperature. Beware, the mix can easily get cold enough to freeze the beer solid and break the bottles by expansion. Calcium chloride works even better, because it is more soluble. If you try really hard you could reach 0 deg F. A fellow named Fahrenheit did it once :) Jerry DOC0060 Subject: Re: Results - Was "Sugar and Diet Coke" From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/22 Message-ID: <3pp7ch$qrt@geraldo.cc.utexas.edu> Newsgroups: sci.chem,k12.ed.science In article , WILSON BROWN DODSON says: > >Based on prior help this newsgroup, we conducted our 4th grade science >fair project on the effect of sugar on 5 different sodas at 3 different >temperatures (room temperature, set in the hot sun and refrigerated). We >recorded the number of ounces left in each can of soda after adding a >teaspoon of sugar to the can. We also tried each temperature under 3 >different conditions (a regular can, a shaken can and a can that had been >left open for 5 hrs). > >At room temperature, the biggest eruption occurred when we opened cans of >soda without shaking or leaving them open. A little less came out of the >cans when they had been shaken, and a lot less came out when they had >been left open for 5 hours. > >When set in hot sun, the results were relatively the same as at room >temperature. However, when left open in the sun for 5 hours, all the >carbonation was gone and there was no eruption at all. > >When refrigerated, the results were completely opposite from either room >temperature or being set in the hot sun. The biggest eruptions were when >the cans were left open in the refrigerator for 5 hours!??? We haven't >been able to figure this out. There was still a lot of carbonation left >in the refrigerated cans after 5 hours. > >The data appears at the end of this message. > >Apparently, the carbonation has something to do with the eruption effect >of the sugar. When a can has been left open for 5 hours, the carbonation >is gone and the sodas don't erupt at all. Shaking the can before opening >it releases some of the carbonation before the sugar is added. So the >sugar did not cause as much of an eruption. We just can't figure out >the effect of the refrigeration. Any help?? > Can I take a guess, huh, can I (raises hand)? My guess is that the sugar crystals act like little boiling chips, that is they provide tiny nucleation sites for the formation of CO2 bubbles from the super saturated solution. At higher temperatures, the crystals dissolve quickly and the nucleation sights are lost before all the excess CO2 is purged. You might test this theory by seeing if you can find a preferably porous, particulate material that does not dissolve and watch the bubble action on soda pop in a glass or by watching the effect of single grains of sugar dropped in a clear container of soda. Seven up or club soda might clarify things (ouch). Jerry DOC0061 Subject: Re: salt & ice. Cool beer question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/23 Message-ID: <3ps9rq$s4i@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , efresco@Bush.edu (E.Fresco) says: > >In article <3pob32$7b5@geraldo.cc.utexas.edu>, glhurst@onr.com (Gerald L. >Hurst) wrote: > >> The salt lowers the melting temperature. Beware, the mix can easily >>get cold enough to freeze the beer solid and break the bottles by >>expansion. >> Calcium chloride works even better, because it is more soluble. If you >> try really hard you could reach 0 deg F. A fellow named Fahrenheit did >>it once :) >> >> Jerry >First of all Jerry is wrong. [Balance of illiterate babbling omitted] Sorry, Sonny, but Jerry is quite right and, although you are correct in your statement that CaCl3 (ideally) yields 3 ions per formula unit versus only two for NaCl, you have to realize that when a chemist talks about "solubility" as a colligative property, he or she automatically refers to the relative number of particles in solution, because he knows that every other chemist will know enough to factor in ionization or known dissociation. Drop that convoluted explanation of the freezing point depression and learn something about the molal freezing point depression constant and the concept of activity. Calcium chloride "works better" because it is more soluble in both gram formula weights and number of particles in solution at 0 deg C and so your ice bath gets to sub-zero quicker. The ultimate low temperature you can reach with table salt is slightly below 0 deg F, possibly lower than with CaCl2 because of the relatively high temperature coefficient of solubility of the latter. If you think you can figure out definitely which can get colder, don't forget to take into account super cooling effects which may give transitory lows. DOC0062 Subject: Re: salt & ice. Cool beer question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/24 Message-ID: <3pulg2$bqo@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , oakes@lbl.gov (Charlie Oakes) says: > [Lots of good stuff omitted] I got lots of feedback on this subject. I thank Mr.(Dr.) Oaks for kindly reminding me that there is a difference between kinetics and thermodynamics and that the molal freezing point depression constant isn't really constant. One can't depend on anything these days, not even constants. That -49.x deg C freezing point depression for calcium chloride brine really caught my attention. Does anybody have a cite for that information? I had no idea it was that great. Is the equilibrium solid the hexahydrate at that temperature? No fair invoking multiple solid phases unless they are thermodynamically stable at that temperature. Jerry DOC0063 Subject: Re: salt & ice. Cool beer question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/24 Message-ID: <3pujgi$bqo@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Lev Gorenstein says: > >.................. > in your statement that CaCl3 (ideally) yields 3 ions per formula unit. > >Well, Gerald,........... But of course it was a typo of yours. I'm just >using it to show you how bad you looked. > Thanks for the benefit of the doubt about "CaCl3" being a typo. That's mighty decent of you. That was certainly a heartfelt set of flames that followed. I can only say that I humbly apologize to your protege, Zack and that I never would have been so unthinking if I had realized my unkind prose would bring such swift and barbed retribution. I admire the way you are able to dash off your chastizing criticism without a lot of academic fussing over grammar and syntax. This literary ability is rare even for those whose native language is English. By the way, although I understand that you feel that people should not talk of solubility in terms of individual ions, I have a technical question which I can most easily phrase in such a normally unacceptable fashion. Given that any cations are acceptable, what set of ionic nitrates in about what amounts would produce the highest stable amount of dissolved nitrate ion at about 0 deg C. A good place to start might be with Ca(NO3)2 and NH4NO3? The question is not merely academic. Zack, if you have a bash at this one, I promise to be nice. Jerry DOC0064 Subject: Re: Flash Point (Was: toxicity) From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/25 Message-ID: <3q34tf$dke@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , ctho461@ecy.wa.gov (Craig Thompson) says: > >Def 1 >>>The minimum temperature that will enable combustion (or explosion) to take >>>place. > >Def 2 >>Flash Point >>- the lowest temperature at which the sample will produce sufficient >> vapours that can be ignited by the application of a flame. > >There's a difference? Well, there's a bit of difference. One might tend to confuse the fire point with the flash point. The former is somewhat higher than the latter (someone said a few degrees, but a few tens of degrees might be more typical) and corresponds to the temperature at which the (thick) condensed source of the vapor will continue to burn if the vapor is ignited. If a sample of gasoline has a F.P. of -40 deg (F or C, take your choice) the vapor above a (sufficiently deep) pool of the liquid may blow a building down, but it will not ignite the pool. A more rare embrous burning material such as charcoal can combust at temperatures way below its flash point. Chemical handbooks are less likely to carry flash point and fire point data than they used to be. Somebody should tell the publishers that the ever increasing proportion of high-tech data at the expense of some of the old nuts and bolts physical properties of poorly defined materials doesn't help us poor dirty-hands chemists who try to analyze the cause and origin of fires and explosions. MSDS sheets are about the best source of flash point data these days. Has anybody seen a recent reasonably exhaustive compilation of values or even a good old one? Jerry DOC0065 Subject: Re: salt & ice. Cool beer question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/25 Message-ID: <3q189p$7q6@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , oakes@lbl.gov (Charlie Oakes) says: > >it is indeed Dr. Oakes > >the -49.x C fpd for CaCl2 is something that i've personally measured. >the reference to my paper is: > >Geochimica et Cosmochimica Acta v. 54 p 603-610 1990 > >unfortunately i wrote that paper when i was less enlightened than i am >now and the units are in terms of wt% and my fit is not particularly >based on good statistics or for that matter good scientific thought. but >the data should be of good quality (and least some folks think so). > >references to prior fpd measurements in this system are in the paper. > >the hexahydrate is supposed to be the stable phase at the eutectic. i >just took other people's word for that and didnt actually identify it >myself. in the NaCl-CaCl2-H2O ternary. the dihydrate of NaCl is the >other stable hydrated salt phase. another possible pt of interest since >you do allude to metastability is that nucleation of the hydrated CaCl2 >salt and ice for that matter can be particularly tricky in this system >but that depends on a lot of other factors. my interest at the time >was with regard to fluid inclusions (a geological thing) and i've found >that at high CaCl2 mole fractions, nucleation of any solid can be damned >near impossible in fluid inclusions. going the other way (in temperature) >the NaCl dihydrate can persist metastably into the NaCl stable field by >as much as 10-20 C. Thank you very much for the highly informative reply. I've had a sort of fascination for CaCl2 solutions ever since I did a little work with the Michigan brines (35 years ago), reacting them with fired dolomitic limestone to precipitate Mg(OH)2, which I subsequently fired into Periclase in a zirconia furnace and evaluated for use in steel furnace linings. Is the propensity of the very concentrated solutions to remain supersaturated related to the relatively high viscosity? I have developed and helped to develop some products which rely on what I'd call kinetic stabilization to maintain both supersaturated solutions and supercooled liquids through transportation, storage and handling, but I am far from being an expert in the field. Jerry DOC0066 Subject: Re: salt & ice. Cool beer question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/25 Message-ID: <3q19ov$7q6@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Lev Gorenstein says: > >I hope I wrote my thoughts clearly enough. In fact I do concern about >this question (my English, not solubility) very much. > >Lev. > Lev, Your English is more than adequate to carry on any conversion you wish to. Most of us wish we could say the same about ourselves with respect to any number of languages and probably especially Russian. Since I don't know Russian, I can't say for sure, but I would guess that we take more liberties with our spoken and informally written language than you or, say, a typical European would be apt to do in their native languages. In particular, we have a very prevelant habit of developing specialized words and phrases peculiar to particular disciplines in industry, where we may communicate a lot, but publish little or nothing. The language used in formal publications is another thing entirely. There we show more decorum, and try to write a reasonable facsimile of the Queen's English. In looking at a non-stoichiometric redox reaction, for instance, I might say "It's was an 80 O.B. (oxygen balance) mixture." This phrase would not really be understood outside a limited industry where it implies that there was enough fuel in the mixture to react with 80 percent of the oxidizer present. Other such jargon may be common over a large number of industrial laboratories, but seldom heard in the halls of academe. Of course, we all try to remain conversant with the more formal language in case one of wins a Nobel prize and has to give a speech :) Jerry DOC0067 Subject: Re: salt & ice. Cool beer question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/26 Message-ID: <3q3upt$qoh@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3ptba1$qh9@ucunix.san.uc.edu>, roberts@ucunix.san.uc.edu (Michael Alan Roberts) says: > >Calcium chloride is about as soluble as sodium chloride in water, for >the purposes of THIS discussion. However, you cannot lower the freezing >point of water to zero degrees Fahrenheit by this method, or even close >to that figure. That's a very well thought-out article you composed. You may get some flack Lev Gorenstein, who doesn't like to see his young friend criticized for lack of coherence (babbling). The above paragraph, though, has me completely baffled. Are you saying that one can't lower the freezing point of water with either NaCl or CaCl2 to below 0 deg F ? My understanding is that you can go below that temperature with the sodium salt and Dr. Oakes tells me that you can get down to below -49 deg C with CaCl2. Furthermore, Dr Oakes informs me that CaCl2 forms such a stable supercooled liquid at very low temperatures that one cannot induce it to precipitate at all. Sounds to me like reaching 0 deg F would be childs play for Dr. Oaks. I haven't had an opportunity to read the paper he published on this subject, but I'm looking forward to it. Jerry DOC0068 Subject: Re: Cleaning Silver in the Home? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/30 Message-ID: <3qfgj4$14n@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3qafns$aoi@news2.deltanet.com>, Rob Kelle says: > >Wow! > >This forum is way out of my league. I searched it out for a reason, however. I recall >learing in highschool chemistry a way to clean silver utensils etc. using hot water, salt >and something else found in most every home. Could someone please remind me of >what to use and in what ratios? > One method is to place the silver in an aluminum pan under a solution of sodium bicarbonate or or you can use glassware and aluminum foil as long as the silver is touching the foil. Be sure to wash any oil or grease off the silver before treating as this method relies on the electrolytic reduction of silver sulfide tarnish. Copper is often cleaned by scrubbing with vinegar-dampened salt. I use this method all the time for my copper-bottom pans. I assume that either the chloride or the acetate helps solubilize the copper in the oxide tarnish, but I'm sure one or more of the other chemists in this forum will tell us exactly what occurs. Jerry DOC0069 Subject: Re: crystals From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/05/30 Message-ID: <3qffr1$14n@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3qfd0o$gjo@news.ysu.edu>, bg634@yfn.ysu.edu (Itala Sorice) says: > > >in an attempt to illustrate the formation of crystals we performed >an experiment using various cham. substances(baking soda,epsom >sl salt, sodium ferrocyanide, ammonium ferric sulfate, pottasium sulf >sulfate, sugar) A brief sketch of set up--6 test tuv tubes filled >1/2 with water and 6 subs. added until no more could be dissolved >A one hole stopper placed in tube e with a string inside and a co >copper ring on the end. It sat for 3 days and only the baking >soda formed a cystal. We conclude that the reason why the other >sol'n didn't form crystatls was because we didn't allow enough >solute to dissolve. Could there be any other explantions?/ >I thank you in advance for any help--please respond to me either >through gopher or to my E-mail (canf_207) >itala Sorice Did you heat the solutions to assure saturation? If you dissolve material at room temperature, the solution will only reach saturation after a very long time and usually only if you have an excess of the solid. I would prepare the solutions at a higher temperature and filter them while still warm. If they do not crystallize within a day or so, add a tiny seed crystal of the same material to overcome super saturation. You really have to warm sugar solution for a while with stirring because sugar is very soluble. The sugar solution is quite viscous and so you must be very patient in waiting for the crystals to grow into "rock candy." Jerry DOC0070 Subject: Re: Flash Point (Was: toxicity) From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/06/05 Message-ID: <3qvhje$o7k@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3qv0n4$oqe@seralph9.essex.ac.uk>, whean@solb1.essex.ac.uk (Wheatley N) says: > >In article ctho461@ecy.wa.gov (Craig Thompson) writes: >>Def 1 >>>>The minimum temperature that will enable combustion (or explosion) to take >>>>place. >> >>Def 2 >>>Flash Point >>>- the lowest temperature at which the sample will produce sufficient >>> vapours that can be ignited by the application of a flame. >> >>There's a difference? > >Yes, the latter is lower than the former! If a substance is above its >flash point, its fumes are flammable - they can be ignited, but not unless >the local temperature exceeds the ignition point (Def 1) > >Nigel Actually, there are cases where the ignition temperature is lower than the flash point. Embrous combustion, as in the case of charcoal, may occur well below the flash point. Jerry DOC0071 Subject: Re: Fluorine gas From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/06/19 Message-ID: <3s49ng$pie@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3s41tp$5qb@liberator.et.tudelft.nl>, dejong@cpt6.stm.tudelft.nl (Maarten D. de Jong) says: > >How is fluorine gas handled in laboratory equipment? I've heard somewhere >that it _can_ be handled in glass, provided it's dryer than the Atacama- >desert, and the glass is replaced often. While I'm at it, are there any >uses for pure F2 instead of HF or something similar? > Fluorine is usually handled in stainless steel, monel or copper apparatus. In theory dry glass is OK, but in practice one always tends to find SiF4 in most reaction products. Because of it's potent oxidizing power you can make all sorts of compounds one could not derive from HF. Chlorine pentafluoride from ClF3, for example, or the ring -CF2N=NCF2- via AgF2 from AgCl and F2 or the exotic "FEFO" explosive F(NO2)2C-CH2-O-CH2-O-CH2-C(NO2)2F by aqueous fluoination or xenon tetrafluoride or the nitrogen fluorides, NF3, N2F4 and N2F2. When Moses and I were young we used to generate fluorine as we used it in the lab. Later, when I rebuilt an AEC electrolytic cell I had the pleasure of collecting tons of the material over a period of months in a large home-made SS dewar from which it was moved around by cryogenic methods and reacted at about 400 deg F and 2400 psi in monel bombs with SS bellows valves. For lower pressures we used Hoke diaphragm valves with home-made copper seats. We had a lot of fires and explosions, and got poor milage from our very, very expensive valves. In the laboratory, working with metal vacuum systems is a royal pain compared with glass vac lines. You can pump and flame forever after your first reaction, but the degassing of the surfaces is never complete. Jerry DOC0072 Subject: Re: Your view:fundamental question in ENTROPY From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/06/19 Message-ID: <3s4edm$pie@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , E11541@CHEMICAL.watstar.uwaterloo.ca (Waterloo Team) says: > >In article <3s3sk9$1go@news.ecn.bgu.edu> cudap@uxa.ecn.bgu.edu (Donald Probst) writes: >>From: cudap@uxa.ecn.bgu.edu (Donald Probst) >>Subject: Re: Your view:fundamental question in ENTROPY >>Date: 19 Jun 1995 13:04:09 GMT > >>Jasper Li (ab391@torfree.net) wrote: >>: De Pauw Edwin (depauw@gw.unipc.ulg.ac.be) wrote: >>: : In article (Dans l'article) <3qnl2h$13ul@ns3-1.CC.Lehigh.EDU>, >>: : aas3@Lehigh.EDU wrote (écrivait) : > > >>: > Suppose that a chamber is divided into two equal compartments. Compartment >>: > A contains N atoms (exactly the same) at pressure P and temperature T. >>: > Compartment B has the same number of atoms at pressure P and T. The atoms >>: > in A and B are exactly alike physically and chemically except that those >>: > in A are red and those in B are green. If thses atoms are allowed to mix, >>: > does the entropy of the system remain constant or increase ? If there is >>: > an increase, in what way is there less energy available to do work ? >>: > Does the entropy change, if any, have units of energy/degree absolute ? >>: > This is a fundamental problem. >>: : > > >>Well, I suppose one way to look at entropy is to examine what would have >>to occur to bring it back to its starting state. For instance, if you >>put a ball at the top of the hill, it will roll down by itself, >>but it won't go back up the hill unless some kind of effort is put forth, >>either energy or work. Since for all practical purposes, the green and >>red atoms will not by themselves return to their respective compartments, >>I'd say it constitutes an increase in entropy. > > >The answer to your question depends the final conditions. >Is the final T and P the same as that of each gas initially? >Assume that this is so. Then the final total volume is double that >of the each gas initially. Entropy is increased because the >individual gases have been expanded to twice their initial volumes. >Because of the expansion the gases have lost capacity to do work. >The total entropy increase is 2Rln2. OK, then suppose I have a box partitioned into two identical chambers. Both chambers are filled with air at the same T and P. I call the left chamber molecules "lefties" and the right chamber molecules "righties." Now I remove the partition and let the contents mix to a homogeneous blend of lefties and righties. Does the entropy increase? Of course it does, because the contents of each chamber have expanded to twice the initial volume. OOPS, that's some kind of nonsense, isn't it? Then why do we believe that it might be different for molecules which differ only in color? I suggest that the difference lies in the direction blindness of the Maxwell Demon. If this little guy had a sense of left and right he could open his frictionless door only when a molecule (or a hot molecule) was approaching from the right and wind up with either all the gas or at least all the hot gas in the left compartment, ready to do some work. Since this phenomenon never seems to occur, we have to conclude that the second law is true merely because of the Demon's dyslexia. It appears that the demon's weakness applies only to directions, not to identifiable physical characteristics. Demons are like perceptive semi-permeable membranes; they can select what they let through. Substitute a non-color blind demon for the partitioning piston membrane in the classic experiment which illustrates that the mixing of dissimilar gases can produce work and, voila! you can get work from red molecules moving freely through the door the the tiny fellow shuts at the approach of the blue ones, regardless of the direction of approach. I propose that the mixing of any two gases results in an increase in entropy providing only that the two types of molecule differ in some physical attribute other than the direction of motion. Jerry DOC0073 Subject: Re: Exlosives 2nd try From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/06/20 Message-ID: <3s7h9f$4u9@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3s6uio$mfm@draco.unm.edu>, bcls@unm.edu says: > > No, I don't want to make explosives and any one who asks me >can expect a nasty flame. > Does anyone know how much (in dollars please) large amounts >of RDX would be? Say 100 metric tons? This is related to a thread in >sci.space.tech about the use of explosives as a propellant in space >engines (please don't post about how strong the material that the >engine is made out has to be, that isn't relevant for this type of >engine). RDX is also known as T4; Hexogen; Cyclonite; Cyclotrimethyl >-trinitramine; 1,3,5-trinitro-1,3,5-triazo cyclohexane; hexahydro >-1,3,5-trinitro-s-triazine. It is used in many plastic explosives >so prices there might be enough. > The best mix is Compound A-3 which expands at 8837m/s which >gives a theoretical specific impulse of about 900s (for those of >you who are interested). > It's been a long time since I've purchased any surplus RDX, but the last material I remember was about one dollar per pound. Composition A-3 is 9% wax and RDX is already fuel rich so I would think one could do better with another mix replacing the wax with an energetic additive having a high oxygen balance. Jerry DOC0074 Subject: Re: Your view:fundamental question in ENTROPY From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/06/20 Message-ID: <3s6v9d$ikk@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3s4llo$7uv@seymour.sfu.ca>, gay@sfu.ca (Ian Gay) says: > >In article <3s4edm$pie@geraldo.cc.utexas.edu>, > glhurst@onr.com (Gerald L. Hurst) wrote: > >[stuff] >>OK, then suppose I have a box partitioned into two identical chambers. >>Both chambers are filled with air at the same T and P. I call the >>left chamber molecules "lefties" and the right chamber molecules >>"righties." Now I remove the partition and let the contents mix to >>a homogeneous blend of lefties and righties. Does the entropy >>increase? Of course it does, because the contents of each chamber >>have expanded to twice the initial volume. OOPS, that's some kind >>of nonsense, isn't it? > >Not really: >This one has been around for a long time, and is known as the Gibbs >paradox (That there is an entropy change when the gasses are different, >but not when they are the same - not sure if Gibbs is really the >originator.) > >The resolution, I think, is that indistinguishability (sp?) is for real, >and you have to allow for it when counting microstates. (The infamous N! >in the statistical mechanics chapter.) Quantum mechanics rules! (for >now) I am pleased to learn that the illustrious Dr. Gibbs and I have something in common. The question of what constitutes distinguishable characteristics among molecules is precisely what I was attempting to address. The Maxwell demon (metaphor for semipermeable membrane) cannot distinguish between left and right and he cannot distinguish molecules by their history of residing in compartment A or B. When we pose a question relating entropy to the "color" of molecules, the real question is "what do we mean by color." The implied meaning is that the color has no real effect, i.e that there is no real method that could be used to separate the species. If this is so then the entropy of a mixture of reds and blues is only higher than that of the pure colors because I say it is, that is because the same demon who can segregate by color could just as well know left from right or lefties from righties (by tracking their histories) and could give us perpetual motion. Entropy as a philosophical concept of the measure of randomness may well concern itself with colored molecules, but thermodynamics as a science concerned with energy might consider mixtures of reds and blues no more entropic than lefties and righties despite the fact that we are able to express the exact delta S in terms of (unavailable) energy and temperature. Jerry Jerry DOC0075 Subject: Gas expansion and plate velocities From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/06/26 Message-ID: <3slbd2$e7a@geraldo.cc.utexas.edu> Newsgroups: sci.chem In an article posted in sci.chem,<3s6uio$mfm@draco.unm.edu>, bcls@unm.edu expressed the opinion that RDX or more specifically the wax impregnated version, A3, might make a good propellant. He apparently based his opinion on the erroneous assumption that the detonation velocity could be used as a basis for calculating specific impulse" " The best mix is Compound A-3 which expands at 8837m/s which gives a theoretical specific impulse of about 900s (for those of you who are interested). " Arno Hahma (In sci.chem article , arno@utu.fi) pointed out that the expansion velocity of the gases was at most about 3,000 m/s and that this lower figure would yield a much lower Isp: "No it doesn't. The shockwave does propagate about 8800 m/s, but not the material itself. The propagation velocity of the particles (i.e. the gases) is about 3000 m/s at best. RDX has an Isp of 2561 Ns/kg from an expansion ratio of 100:1. That translates to about 260 s." I don't want to put words in Mr. Arno's mouth, but I assume that he is talking about the "free surface velocity" of the particles, not the "particle velocity,"that is, that he is referring to the faster of the two phenomena. Bill Nelson (in sci.chem article <3sg6o8$qja@odo.PEAK.ORG>, billn@PEAK.ORG) agreed with Mr. Hahma: "Wrong. The propogation rate of the shock wave is about 8800 m/s (at a high enough density). The rate of material expansion is about a third of that. Reduce the velocity to 3000 m/sec, and the Isp becomes about 300s, which is not exceptional at all." It is a well known fact that lined cavity shaped charges using materials like RDX can accelerate metal jets to velocities in excess of 7,000 m/s by collapsing a cone and, for lack of a better analogy, squirting a stream of particles out like fast grapefruit juice drops propelled by a slow spoon. In other words, the hot gasses can propel part of the metal lining at velocities much higher than those of the of the gas molecules themselves. Metal projectiles can also be accelerated to hypervelocities by focusing the detonation wave in a block of explosive into a "reentrant" configuration using a solid cone of steel or glass implanted in the charge. But what about the case of a plane explosive wave striking a flat metal plate? (That's "plane," i.e. "flat." not "plain.") The very capable explosives group at duPont, many years ago published a couple of patents on the use of plane wave driven steel plates to generate extreme pressures on impact for phase change reactions (i.e. carbon to diamond) and for sintering refractory materials (i.e.diamond dust). The charges used were 60/40 composition B or the like (close enough to composition A3 in performance for our purposes) initiated by a plane wave generator. The detonation heads of the rather large charges (20 lbs or so) were used to propel steel plates of about 1.3 mm thickness (in the case of sintering ) to about 5 mm (for phase changes) over a distance of about 4 cm. The reported terminal velocities of the heavier projectiles were about 3,500 m/sec - a bit more than the gas expansion velocities mentioned by Mr. Arno and Mr. Nelson. However, the lighter plates, as I recall, were reported to have been accelerated to about 5,000 m/s, a value slow by comparison to shaped charge jets, but fast compared with reported gas cloud expansion velocities. Now comes the tricky part: How to explain why duPont's plates are reported to move faster than Mr. Arno's and Mr. Nelson's gas molecules? One possibility, of course, is that I have had another memory lapse concerning duPont's data :) Jerry DOC0076 Subject: Re: Gas expansion and plate velocities From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/06/26 Message-ID: <3slcip$e7a@geraldo.cc.utexas.edu> Newsgroups: sci.chem Pardon me for posting the subject article "Gas expansion and plate velocity" in this forum. I was excerpting material relevant to alt.engr,explosives and accidentally sent the edited document to sci.chem in the "synopsis and comment" form designed for the other group. Jerry DOC0077 Subject: Re: H2S instead of H2O From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/06/26 Message-ID: <3sl1ft$e7a@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3skb3v$cf4_006@netcom.com>, eleusis@netcom.com (Eleusis) says: >> >> Since I'm always curious about possible >>alternatives to life as we know it, I'm wondering whether H2S >>might have properties similar to H2O that would also let it >>serve as a suitable solvent. I'm not assuming that the same >>biomolecules would be involved. > > >Good question. The answer is: They both will kill you if you breath them. > >Really, H2S is an extremely poisonous gas with the odor of rotten eggs. Of >course, breathing water will drown you, but that is where the similarity >ends ;-). > Poisonous to us Humans, yes, but there are creatures in the sea ( e.g. tube worms, I believe) that are nourished by H2S escaping from volcanic vents. I remember once marveling at bacterial growth on the surface of a sodium thiosulfate solution in a chem lab bottle. I guess one species' poison is another species' meat and potatoes. Who knows whether there is some critter in the universe that swims in a hydrogen sulfide sea? Personally, I tend to favor ammonia as the alternate to water, but that may be simple prejudice on my part. Jerry DOC0078 Subject: Re: What are HCI and NaOH???? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/07/03 Message-ID: <3t82da$dm@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3t6rk8$ej1@oban.cc.ic.ac.uk>, s.hogg@ic.ac.uk (Simon Hogg) says: > > >> >>In article <101323Z30061995@anon.penet.fi> an297554@anon.penet.fi writes: >>>From: an297554@anon.penet.fi >>>Date: Fri, 30 Jun 1995 10:12:27 UTC >>>Subject: What are HCI and NaOH???? >> >> >>>What is HCI and what is NaOH? >>>Please follow the h2o = water / n2o = nitrous oxide format. >>HCl = hydrochloric acid / NaOH = sodium hydroxide > >Why did the original post come via an anonymous server???? > If you spelled HCl with a capital "I" you'd want to remain anonymous too. DOC0079 Subject: Re: help! where can i buy iron sulfide?! (or make my own!) From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/07/09 Message-ID: <3tnoj4$i28@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3tkgbp$1l2@chem1.chem>, jejanes@mtu.edu (Jeff E. Janes) says: > >JMacd (jmacdon1@fox.nstn.ns.ca) wrote: >: i tried to make it myself by placing powdered sulfur and iron fillings in a >: test tube and heating it, but all that gave me was a hard yellow lump with >: iron specks in it, not iron sulfide as it was attracted to a magnet. it > >Did you try crushing the hard yellow lump and look through remains for >more iron? If there seemed to be less iron specks than what you started >with, it had to go someplace, maybe into iron sulfide. Sulfide with >bits of iron embedded in it would be attracted to a magnet. > Try adding some water to the Fe/S mixture. The mixture will furnish its own heat after a bit and boil the water while making FeS. Jerry DOC0080 Subject: Re: Need info on cryogenics From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/07/26 Message-ID: <3v4n09$se3@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Lev Gorenstein says: > >On 23 Jul 1995, Roy Newton wrote: > >> I have been required to do a speech for a class. The topic that >> I have chosen is cryogenics; specifically, people who have terminal diseases >> and are being frozen in hopes that we will find a cure and a method for >> dethawing somewhere in the furure. >> Information on this topic has been difficult to find. >> Any info will be greatly appreciated. >> >> Please respond via email: rynewton@infi.net > >Was there any real person who went for this? The idea itself was long >ago discussed in SciFi and media, but in real life was it ever done? >Just curious. > >Lev. > Yes, it's been done many times. For a vivid description see a book titled something like "The Great Mambo Chicken...." I've got a copy around here somewhere, and, if I find it, I'll post the exact Title or send email. There are or were no less than two companies in the business. They use liquid N2 to freeze and maintain bodies in large Dewars for a price. Or you can get the economy process in which they merely sever and freeze your head. The heads apparently tend to split open, but I guess they figure future generations will be able to handle that little problem. Personally, I prefer the California economy burial ($200) in which they put you in a spike-shaped coffin and hammer you into the ground. Jerry DOC0081 Subject: Re: Need help finding C-N compounds From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/03 Message-ID: <3vpre0$lkg@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3vpaf7$dt3@solaris.cc.vt.edu>, teter@vtaix.cc.vt.edu (David M. Teter) says: > > >I am trying to obtain some C-N compounds for my research. > >All I have been able to get so far is tetracyanoethylene (C6N4). > >I would appreciate if anyone could give me a source for: > > tetracyanomethane (C5N4) > dicyanoacetylene (C4N2) > cyanuric triazide (C3N12) > >If anyone knows of any other C-N compounds, and a source for >obtaining them, please let me know. > How about my personal favorite, cyanogen, (CN)2? I made and fluorinated this nifty little molecule to make the explosive four membered ring -CF2-N=N-CF2- way back when chemistry was still a respectable profession. Jerry DOC0082 Subject: Re: Twink - What's in it? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/06 Message-ID: <401qj2$g87@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3vv4j3$l86@tpsun.taranaki.ac.nz>, Stephen Watkins says: > >Hi - > >Could anyone tell me exactly (well, more or less) what chemicals go >into correction fluid? Also, what was the purpose of the 1,1,1 >trichloroethane that was added to the fluid a couple of years ago? > Specifically, I better not say, but generically the ingredients are: Solvent Resin Plasticizer Dispersing agent Pigment Toner 1,1,1-trichloroethane was not "added" a couple of years ago in the USA or Europe. It was in widespread use in those areas in the 1970's. In those days ozone holes were not a problem and the compound was THEN considered the safest of the chlorocarbons. Today one might choose a CHF compound for such an application requiring low falmmability and high evaporation rate. There are, of course, also water-based fluids which are sometimes used for photocopy correction. These formulations dry more slowly. Jerry DOC0083 Subject: Re: Ammonia gas removal from air. From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/07 Message-ID: <404g83$3jn@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <404dfp$7ja@news.sas.ab.ca>, rdh@fn1.freenet.edmonton.ab.ca () says: > > >I don't believe there is any dry chemical to scrub ammonia from the air. >Ammonia scrubbers require wet conditions, low pH, and a packing tower (or >the like). The only "dry" chemical that would come close to removing >gaseous ammonia is calcium hypochlorite dust. This would oxidize ammonia >but wouldn't be effective and may produce a dust far worse than the >ammonia ever could be. > I don't see why solid ammonia absorbants wouldn't exist. We use numerous salts to remove water from air by forming hydrates. There are many instances where an ammoniate is more stable than the analogous hydrate and it follows that the corresponding substrate salts should also be capable of absorbing gaseous ammonia preferentially. Jerry DOC0084 Subject: Re: Ceramic-filled Paint From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/07 Message-ID: <4048j4$3jn@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <1995Aug6.053305.16579@lafn.org>, ab425@lafn.org (Walter Blackman) says: > > >Does anyone in cyberspace know about the effectiveness of Ceramic-filled >paint and whether its properties warrant its application as a house paint? > >Would appreciate any information on this type of application and whether >its hype as used on space tiles makes it a good choice for a water based >paint on my house in ~Los Angeles? > Sounds like mousemilk to me. The normal titanium dioxide pigment used in ordinary white paint is more than adequate in its role. A ceramic powder would likely not have the high refractive index of TiO2 and would provide less hiding power. Nobody really cares about hiding power for reentry vehicle tiles and we certainly don't need to protect houses from reentry environments. Jerry DOC0085 Subject: Re: The quick & easy "lava lamp" From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/07 Message-ID: <405u74$boi@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <405gs5$cmv@sunsystem5.informatik.tu-muenchen.de>, fenk@Informatik.TU-Muenchen.DE (Connor) says: > >Jim Webb (jnw4347@email.unc.edu) wrote: >: After a great deal of experimenting, I've recently found a simple and cheap >: recipe for making these chemistry demos, which does not involve hard-to-get >: (and pricey) benzyl alcohol. It's so easy, my mind reels with the >: possibilities: lava lamp street lights? lava lamp votives? lava lamp hood >: ornaments? lava lamps with lampshades? > >: Enjoy. >: Jim > >Great. Thank you very much. > >I have searched nearly 2 months for a solution of this problem. But >there was nobody who can give me a answer. Postings in german >newsgroups, asking in shops where they have such lamps, the men from >the Technischen Museum Muenchen even don't knew it and have bought the >liquids, WEB and library search - all negativ. > >I have tryed to use wax and water (glycol, later alcohol), because >some told me. With alcohol it works a little, but the wax wasn't >liquid. > >The last solution seems to be, buying a replacement glass cylinder >filled with these mysterious liquids, but it is expensive ... > May I suggest that you try a mixture of heavy mineral oil and a dense (>1.0), water insoluble organic liquid or solid? A starting point might be a blend of the oil with a phthalate ester adjusted to yield a specific gravity slightly higher than water. Obviously, one of the chlorowaxes might also serve as denser component. I'll bet others in this forum can come up with a hundred other candidates. One problem you may have to look out for is the possibility that some organic phases will tend to emulsify at the interface. but you can check this with a simple test tube experiment. DOC0086 Subject: Re: Twink - What's in it? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/07 Message-ID: <4049fr$3jn@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , B.Hamilton@irl.cri.nz (Bruce Hamilton) says: > >In article <3vv4j3$l86@tpsun.taranaki.ac.nz> >Stephen Watkins writes: > >>Could anyone tell me exactly (well, more or less) what chemicals go >>into correction fluid? > >My guess would be a white pigment with good blocking power, >perhaps titanium dioxide, along with some binders and thinners. >You might like to contact Mitchell and Dean Limited of Auckland, as they >produced it. > >>Also, what was the purpose of the 1,1,1 >>trichloroethane that was added to the fluid a couple of years ago? > >It was the volatile, non-flammable thinner that enables Twink to dry rapidly. >The higher density of organochlorine solvents allowed them to disperse >the pigments and binders for longer - but they still required agitation, >just like paint. 1,1,1-TCE was replaced because it is due to be phased out >under the ( ozone layer protecting ) Montreal Protocol. > TiO2 is correct, but the choice of 1,1,1-TCE had nothing to do with the relatively high density of the chlorinated materials. Viscosity and thyxotropy control are much more important factors because of the large difference between the density of TiO2 and any common solvent, chlorinated or not. I wish I were free to discuss the technical aspects of type correction fluid formulation in greater detail. There is a great deal more art and science associated with these mixtures than one might suppose. Jerry DOC0087 Subject: Re: Potassium Permanganate - What is it? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/08 Message-ID: <406t6f$26k@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , martind@lincoln.ac.nz (Dean Redfearn Martin) says: > >Hello all. I have just found a bottle in my shed labelled Potassium >Permanganate. I was wondering if anyone could tell me the typical uses for >this. Is it likely to be useful to me, or should I just throw it out? If the >latter, how should it be disposed? > Dilute solutions of the material used to be used to kill athletes foot fungus. It is a strong oxidizer, so you don't want it in contact with organic materials. Acids are also a no-no because they exacerbate the oxidation problem. It's nice to see someone trying to get rid of the stuff for a change. The kids on the net are always looking for the stuff for pyro purposes. Permanganate is used by bluejeans manufacturers to bleach (streak) denim to make it look old. If you have any chemist friends, offer it to them. I've got a bottle of the stuff around here somewhere, myself - left over from some consulting job or other. Hmm. Anybody need a gallon or so of merthiolate tincture, I think I've got some in the garage near the old cans of vinyl alcohol. Sigh. Jerry Jerry DOC0088 Subject: Re: RECIPE FOR NITROGEN TRI IODIDE WANTED From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/08 Message-ID: <406rmm$26k@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Lev Gorenstein says: > >> Warning: Don't get iodine on clothing or cloth, it'll turn purple. > >Oh yeah! Now I'm certainly sure that you are an idiot. Of course, >purple clothes is the biggest danger of this process... Hell, and we >hear this crap from a person from Harward... > > More likely brown than purple. Jerry DOC0089 Subject: Re: Titration of Nitric Acid with Sodium Hydroxide From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/08 Message-ID: <406rve$26k@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <406bbg$sk2@earth.superlink.net>, nancy@mars.superlink.net (Nancy Gold) says: > >1) NaOH as a titrant can cause problems due to the effect of air oxidation >to form carbonates. Neat trick, oxidizing NaOH to form carbonates :) Jerry DOC0090 Subject: Re: Twink - What's in it? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/08 Message-ID: <408bud$rph@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <95080823102915782@welcom.gen.nz>, jim.oliver@welcom.gen.nz (Jim Oliver) says: > >glhurst@onr.com (Gerald L. Hurst) wrote : > >GLH>In article , B.Hamilton@irl.cri.nz >GLH>(Bruce Hamilton) says: >GLH>> >GLH>>In article <3vv4j3$l86@tpsun.taranaki.ac.nz> >GLH>>Stephen Watkins writes: >GLH>> >GLH>>>Could anyone tell me exactly (well, more or less) what chemicals go >GLH>>>into correction fluid? > >[edited] > >GLH>>1,1,1-TCE was replaced because it is due to be phased out >GLH>>under the ( ozone layer protecting ) Montreal Protocol. >GLH>> >GLH>TiO2 is correct, but the choice of 1,1,1-TCE had nothing to do with >GLH>the relatively high density of the chlorinated materials. Viscosity >GLH>and thyxotropy control are much more important factors because of the >GLH>large difference between the density of TiO2 and any common solvent, > >All true. > >GLH>chlorinated or not. I wish I were free to discuss the technical >GLH>aspects of type correction fluid formulation in greater detail. There >GLH>is a great deal more art and science associated with these mixtures >GLH>than one might suppose. > >Aww cummon Jerry, any half decent paint/resin/polymer/adhesive >chemist could knock up a batch of correcting fluid. As you said >yourself in another message : > >Solvent >Resin >Plasticizer >Dispersing agent >Pigment >Toner > >Easy peasy. :-) > >It doesn't have to : Pass crosshatch tests. > Last forever under sunlight + rain etc > Have good gloss or be very matte. > Have long shelf life (buy MORE !). > Have extreme flexibility. > Have good heat / cold resistance. > Have good moisture transmission. > Have close tolerances on P.V.C. > etc etc etc. > >A good paint coating has to have all these things ! > >Almost _any_ acrylic/styrene/PVC/ABS etc resin would suffice as >binder suitably tarted up with plasticisers . Pigment grind >tolerances could be comparitively very wide without any >detrimental performance. Most soluble resins have good thixotropy >in perchloroethyelene (now used in Twink), therefore no need for >antisettle agents either. > >And if it does fail in service - who cares ? Not exactly a >million dollar claim is it ? > >The only easier "household" item I can think of is that gunk that >is squirted _directly_ down the toilet bowl to kill germs or >clean "under the lip" or whatever. Become a millionaire overnight >with that stuff. > >Tell us more :-) Golly, I didn't realize there was someone around who knows so much more than I do about type correction fluids. Maybe I should give back the money the Liquid Paper Corporation (Gilette) paid me me to formulate their products. It's a good thing their research staff chemists didn't know how easy it is or they might have (shudder) done the job inhouse. BTW, there are very good reasons why most of the resins you named are not suitable for a COMPETITIVE market and those reasons do not apply to standard paint materials. Pigment grind and other properties of the TiO2 are much MORE demanding than is the case with paints. Perchloroethylene is a very poor solvent choice; it was used in some other brands in the 1970s. Isn't it funny how easy the other guy's work always seems to be? Have you considered the possibility that correction fluids may have their own set of criteria to be met, quite independent of those of housepaint. I am a bit puzzled that you included flexibility and shelflife in your list of properties not required. You might give those two items a few more seconds of thought. Liquid Paper outsells all other brands of correction fluid combined with annual factory sales of several tens of millions of dollars. Perhaps you should take advantage of the situation and grab their market with, uh, oh yeah Twink :) Jerry DOC0091 Subject: Re: imperial units to si units conversion From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/08 Message-ID: <406rgd$26k@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <405vv8$lbg@oban.cc.ic.ac.uk>, kz says: > >Dear netters, > >Does anyone knows of any software packages that would do >the above conversions? > >Many thanks indeed. > > >My old Hewlett Packard HP41C does a pretty good job. Jerry DOC0092 Subject: Re: sucrose density From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/08 Message-ID: <408cfu$rph@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <95080823102915783@welcom.gen.nz>, jim.oliver@welcom.gen.nz (Jim Oliver) says: > >dpn@mailhost.tcs.tulane.edu (David P Norwood) asks : > >DPN>A coworker of mine needs the density of solid sucrose. >DPN>Anybody know it? > >Not offhand. > >Get a measuring cylinder (or similar). Half fill it with water >and note the fill point. Preweigh the whole thing. Shovel in >sucrose until it's nearly coming over the top, the sucrose must >be all wetted down (no air bubbles). Now reweigh it and note the >increase in volume. Calculate the rough density by dividing the >increase in weight by the volume increase. Density = Mass/Volume. > >Jim Oliver (3:771/370) > > * SLMR 2.1a * Shin: Device to find furniture in the dark .... Is this supposed to be a joke? This technique only works with insoluble materials. The density of sucrose is 1.587. I want to apologize to Mr. Oliver for my post this date re type correction fluids (Twink-What's in it). I thought Mr. Oliver was a chemist and commented accordingly, but now I see that this is not the case. Jerry DOC0093 Subject: Re: Twink - What's in it? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/16 Message-ID: <40s59d$5gc@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , B.Hamilton@irl.cri.nz (Bruce Hamilton) says: > >I believe the original developers of computers did so solely to avoid >Correction Fluids. They probably assumed that us chemists would >develop a screen cleaner that would rapidly remove the correction >fluid without damage - we have failed them miserably. > >However, I've had this * really bright * idea. - Coloured Correction >Fluids. So many people use word processors that indicate attributes >by differing colours, and also use differing background colours, that >the future market has to be in sets of coloured correction fluids. > When I was busy developing type correction fluids (long ago), I assumed that the stuff would become obsolete in a year or so because of the rapidly increasing number of word processors. Ironically the sales have increased over the years as a result of the increase in the number of photocopies which have to be altered as a result of changing prices in published price sheets. Folks now make hundreds of copies of things we used to make in triplicate and they usually have to make mass corrections that don't warrant reprinting the whole batch. Colored type correction fluid has been available for years. It is custom formulated for executives to match the color of their stationery. Ah, decadence. Although I have tested a zillion strokes of correction fluid in the lab, the thought never occured to me to actually use the material for my own correspondence. Someone remarked that type correction fluid formulations are a low tech matter. Ain't it the truth !! As a working chemist for many decades I have labored in rocket propellants, explosives, coatings, plastics, pigments, forensics, general organic and inorganic synthesis, thermodynamics etc. and I have never done a thing one could consider "Hi Tech." Each year there seem to be fewer guys around who know much about low tech subjects. I like to think they'll miss us when we're gone :) Jerry DOC0094 Subject: Re: sucrose density From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/16 Message-ID: <40s8n1$5gc@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <95081004175915865@welcom.gen.nz>, jim.oliver@welcom.gen.nz (Jim Oliver) says: >>by e-mail. > >Tell me, if you didn't have the figure in a book of sucrose just >how would you determine it's density ? > >[Another more polite person pointed out (by e-mail) that the >method I outlined would be better done using a solvent that the >sucrose was insoluble in, maybe hexane or other less volatile >solvent.] > Your more polite person is correct. You are trying to use the principle of Archimedes, but, in order to assure accuracy, you must use a liquid which does not dissolve substantial quantities of the solid being measured. If the solid is soluble, your accuracy will be a matter of the degree to which the sum of the volumes of the components matches the volume of the solution. The expansion or contraction of the total volume during dissolution will vary according to the solid/liquid combination and the concentration. I gather that your friend Bruce Hamilton has run the experiment you outlined using sugar and water and that he got the value he knew he would get based on the well-known tables of specific gravity for sugar solutions. Is this part of a straight-faced comedy routine by you two? Jerry DOC0095 Subject: Re: sucrose density From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/18 Message-ID: <412qls$r50@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , B.Hamilton@irl.cri.nz (Bruce Hamilton) says: > >This hardly worth responding to, but just in case >anybody seriously believes these comments... > >I detailed the experiment I performed. Anyone can duplicate >it - I performed it during a morning tea break at work. >If you don't get a similar answer, I'd be very surprised. > >I also explained why I decided to perform it - It was not intuitive >to me that sensible results would be obtained. However, unlike >some, I decided not to post until I had tried the experiment. >I was surprised how accurate it was. > OK, now try the same experiment using roughly the same technique with,say, ethanol. Or better yet, let me dry-lab it for you and give the final result: density = ca 0.84 vs 0.79 handbook value. Or how about a thought experiment involving the measurement of the density of ice; the result depends on how much ice is allowed to "dissolve" (read melt) at 0 + deg and the range is some 10%. Phase changes are typically accompanied by changes in the apparent molar volume of the substances involved. It can happen that the change is positive, negative, large or small. In the case of sucrose, the data indicate that the change happens to be small. The method, however, is clearly useless for determining the density of materials whose properties have not already been tabulated unless errors of 5-10 percent are considered acceptable. >I'm glad I bothered to perform the experiment, rather than >make disparging comments about the suggestion, I now >know another quick and dirty non-intuitive technique for >density. > The technique is indeed quick, dirty and non-intuitive. Jerry DOC0096 Subject: Re: colloidal potassium From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/27 Message-ID: <41qjqe$1pd@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.chem.organomet In article , Brian Watson says: > > >I am interested in preparing coloidal potassium by ultrasonic dispersion, >for a Dieckmann condensation, and possibly for other reactions such as >the acyloin condensation. I tried making colloidal potassium, using 0.3g >potassium in 20ml toluene in a 100ml rbf, sonicated with a 35kHz cleaning >bath. I obtained negligible dispersion even after an hour and 15 min. >The paper I was roughly following (Tet.Let 1984 p.753) claimed to disperse >78mg potassium in 15 min, using a standard ultrasound cleaning bath of 35 >kHz. > >Does anybody have any advice? I have never used sonication before. Are >factors such as position in the bath, type of reaction vessel etc critical? >Also, I would be very interested in any references for the use of either >coloidal potassium or graphite supported potassium in organic synthesis. > You didn't mention temperature, but if you have not already done so, you need to heat the mixture above the melting point of the potassium. If you do form the emulsion, you can expect that the colloidal spheres of potassium may remain in the liquid state on cooling to merely warm temperatures, that is they may supercool. I once patented a series of dense, metallized greases prepared by emulsifying low melting alloys (e.g. Woods metal) with greases such as the silicon materials. I purchased an ultrasonic unit with a titanium cup for use in preparing the emulsions, but soon determined that ordinary mechanical mixing with good shear worked much better. Of course, the metals I was working with were much denser than potassium so your results may be different. BTW, the dense greases (>5.5 g/cc) were intended for use in the bearings of submersible oil well drill bearings in units operating under dense drilling mud, which tended to float out lighter greases. Jerry DOC0097 Subject: Re: sucrose density From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/27 Message-ID: <41qmvp$1pd@geraldo.cc.utexas.edu> Newsgroups: sci.chem Article Segment 1 of 2 In article , B.Hamilton@irl.cri.nz (Bruce Hamilton) says: > > >This hardly worth responding to, but just in case >anybody seriously believes these comments... > >In article <40s8n1$5gc@geraldo.cc.utexas.edu> > glhurst@onr.com (Gerald L. Hurst) writes: > >>I gather that your friend Bruce Hamilton has run the experiment >>you outlined using sugar and water and that he got the value he >>knew he would get based on the well-known tables of specific >>gravity for sugar solutions. Is this part of a straight-faced >>comedy routine by you two? > >Firstly, I've mainly had contact with Jim Oliver on sci.chem, >or email concerning the FAQ. Colleague in the same city - yes, >friend - no. > >I detailed the experiment I performed. Anyone can duplicate >it - I performed it during a morning tea break at work. >If you don't get a similar answer, I'd be very surprised. > >I also explained why I decided to perform it - It was not intuitive >to me that sensible results would be obtained. However, unlike >some, I decided not to post until I had tried the experiment. >I was surprised how accurate it was. > >The idea of using alternative solvents does create disposal >problems, and the water result is probably close enough for >many purposes. > >I actually performed the experiment before I consulted >Merck - but nobody is obligedly to believe that - I am >as aware as anyone about the bias of knowing the answer >in advance. If I'd had more time I would have tried the >my suggested volumetric flask enhancement, but I hadn't >expected the quick and dirty measuring cylinder method >to be accurate for water-soluble material. > >I'm glad I bothered to perform the experiment, rather than >make disparging comments about the suggestion, I now >know another quick and dirty non-intuitive technique for >density. > > Bruce Hamilton The above exchange was followed by an email dialog with Jim Oliver in which I continued to challenge and he to defend the use of the principle of Archimedes to measure the density of SOLUBLE solids. In my last message to Mr. Oliver I promised to try to post a clear example of the inadequacy of the method for even what Bruce Hamilton described as "another quick and dirty non-intuitive technique for density." The following thought experiment using arbitrarily selected sodium hydroxide appears to satisfactorily demonstrate that the method is unreliable: Dry sodium hydroxide pellets (76.5 g, 15 deg C) are placed a 100 ml graduated cylinder or volumetric flask 0f known weight. Water is added slowly with intermittent agitation and cooling until the contents are at room temperature and occupy 100.00 ml. The mass of the added water (76.5 g) is determined by reweighing the filled flask and subtracting the sum of the tare weight and the weight of the sodium hydroxide. Using the principle of Archimedes, we assume that the added water occupies a volume of 76.5 ml and that the volume attributable to the NaOH must be 100 - 76.5 = 23.5 ml. The calculated density of the NaOH is about 76.5/23.5 = 3.26 g/ml. Reality check: According to the Merck Index a 50/50 NaOH solution has a density of 1.530 g/ml, confirming that our 100 ml volume is correct for the 2X76.5 g of water and NaOH we combined in the container. Merck also tells us that the density of solid NaOH is about 2.13 g/ml. Assuming that the Merck index value is valid, the calculated error in our measurement is approximately (3.26 - 2.13)/2X100 = 56.5% If this same experiment is run using a final NaOH concentration of only 10%, it will be observed that the specific gravity of the of the solution becomes 1.1110 at 20 deg according to the CRC. Given that the mix is 90 wt. percent water the original volume of water added to form the 100.00 ml solution must be 0.9X1111.0 = 99.99 ml. DOC0098 Subject: Re: sucrose density From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/27 Message-ID: <41qmvp$1pd@geraldo.cc.utexas.edu> Article Segment 2 of 2 For Archimedean purposes we must assume that the effective volume of water in the experiment remains constant at 99.99 ml. Under this necessary condition, the volume attributed to the NaOH must be the difference between the volume of the solution and the volume attributed to the water, i.e. 100.00-99.99 = 0.01 ml. The weight of the sodium hydroxide unnecessarily corrected for the slight numerical difference between the density and the specific gravity of water at 20 deg is 0.1X111.10X.9982 = 11.090 g. We have only one significant figure left from the volume subtraction so it will have to suffice to say that the calculated density of the solid NaOH is 1X10^3, i.e about 1000 g/ml. Obviously the assumption that the effective volume of water used in this experiment remains constant is invalid and it follows that the Archimedean technique will not give reliably acceptable results using highly soluble materials. The error in the measurement of NaOH density appears to be larger than that of most materials based on the limited data available in my personal records, but other substances such as anhydrous MgSO4 at 20% exhibit potential errors of two or three hundred percent, and indeed it appears that the addition of small quantities of some salts to water actually reduces the volume of the mix to less than that of the original pure water. I wonder which solvent/solute pair would yield the largest net drop in volume? Are there pairs that increase in volume on mixing or is the shrinkage a direct reflection of the increased intermolecular forces that drive the dissolution?I suppose that an increase in volume would require the presence of some "structure" in the mixed phase, but this circumstance appears no more unlikely than the existence of the proposed geometric effects which are said to account for the unusual behaviour of water in the 0-4 deg C range. Jerry DOC0099 Subject: Re: ethanol(spell check!!!) From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/28 Message-ID: <41sqfq$gmq@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <41siv9$ur@news2.isp.net>, says: > >Where to buy ethanol 180 or 200 proof. >I am an unlicensed chemist. (student) > Depends on where you live. Here in Texas you can buy Everclear (190 proof, I believe) in the liquor stores. In California the stuff isn't legal. Hmmm, I've been a chemist for several decades; where do I go to get a license ? Jerry DOC0100 Subject: Re: A specific general chem question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/29 Message-ID: <41u8e8$hg4@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <41u16t$an0@geraldo.cc.utexas.edu>, glhurst@onr.com (Gerald L. Hurst) says: > >> >It is true that the calculation of molarity from molality is >a bit difficult without handy solution density data, but the >reverse process is a snap. Why not convert your table of >density vs molarity (i.e weight %) to a table of density vs >molality on the old PC and draw your curves or interpolate >from this more convenient source. If you need to squeeze >out the last bit of accuracy it's hard to beat picking your >values off a carefully drawn curve. Interpolation is good >enough for government work. > Hmm, that "i.e. weight %" should read "or weight %" lest I get brickbatted by an eager grad student looking for notches in his gun. I think I remember the simple conversions: D = solution density M = formula weight of solute P = weight percent of solute Molarity= 10PD/M Molality = 1000P/[(100-P)M] Molality = molarityX100/[(100-P)D] If all three of these are correct, it'll be the first time in two decades that I ran through that much math without some egregious error so check 'em before you use 'em :) Jerry DOC0101 Subject: Re: A specific general chem question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/29 Message-ID: <41u16t$an0@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <41tss2$g75@bubba.NMSU.Edu>, Mark R says: > >Many thanks to all who took the time to answer my last question! Here's a >followup that's perhaps a little more interesting: > >I mix a 1 molal solution of KCl at 20 degrees. To do this I combine >74.55 grams of KCl and 1.0018 L. of water (assuming water density of >0.99821 at the given temp). Can I find the molarity mathematically, or >must I determine the final volume by hand to get molarity? (Let's just >say I need a result more accurate than simply assuming >molality=molarity). > >I couldn't find any tables which give densities for solutions of various >molalities. This raises another question with respect to the CRC >molarity-density tables. Would it be more accurate to construct a >calibration-type curve to estimate molarities or densities not listed >than to simply interpolate between two given points? > >Any attention to these little dilemmas (dilemmae?) is appreciated. > It is true that the calculation of molarity from molality is a bit difficult without handy solution density data, but the reverse process is a snap. Why not convert your table of density vs molarity (i.e weight %) to a table of density vs molality on the old PC and draw your curves or interpolate from this more convenient source. If you need to squeeze out the last bit of accuracy it's hard to beat picking your values off a carefully drawn curve. Interpolation is good enough for government work. Jerry DOC0102 Subject: Re: Why thinking hurts - was Re: sucrose density From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/29 Message-ID: <4206gr$ou0@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , B.Hamilton@irl.cri.nz (Bruce Hamilton) says: > >Actual reality check. > >After work today, I repeated my experiment with NaOH, using both >the pearl and flake forms. I used a 100ml measuring cylinder >filled to 50 ml mark with water. I poured in flake NaOH to the >85ml mark, however it did take about a minute, and considerable >heating occured as the NaOH dropped through the water. >The weight was 78.91 g, 78.91/35 = 2.25 g/ml. The repeat >using pearl NaOH to 90mls weighed 90.72 g, giving 2.27 g/ml. > >As Merck reports 2.13 g/ml, then the error is >((2.26-2.13)/2.13) x 100 = 6.1%, this somewhat different >to your 56.5% error. > >Quick, dirty and non-intuitive, but still useful.... >Others may have different opinions. > > Bruce hamilton Say! that's really good work, a mere 6.1 % density error. Even with temperature compensation that would still yield an error of well under 7%. I suppose if one could run the experiment even faster and maybe use ice water it could be made even more accurate. Having established the error at infinite time at about 56% and the error at one minute at say 6%, what we need is a few more points at inbetween times and perhaps shorter times so that we can construct a time/error curve such that one may extrapolate back to zero time and therebye get a highly accurate value. Do you suppose that the method works better with pelletized and flake material than it would with typical fine granular materials? I'll bet you could get really startlingly accurate results with a 50 cc pressed slug of material and a 15 second experiment. I am learning a lot about unusual experimental methods in this forum and I look forward more in the future. Jerry DOC0103 Subject: Re: colloidal potassium From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/29 Message-ID: <41tv3f$an0@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.chem.organomet In article , Brian Watson says: > > > >On 27 Aug 1995, Gerald L. Hurst wrote: > >> In article , >> Brian Watson says: >> > >> >I am interested in preparing coloidal potassium by ultrasonic >> >dispersion . . . > > [remainder deleted] > >> You didn't mention temperature, but if you have not already done >> so, you need to heat the mixture above the melting point of the >> potassium. If you do form the emulsion, you can expect that the >> colloidal spheres of potassium may remain in the liquid state on >> cooling to merely warm temperatures, that is they may supercool. >> > [Some interesting material about metallated greases deleted] > >Thank you for your reply. I'm not sure I understand you correctly, however. > >There is a procedure in Organic Syntheses for making potassium sand by >refluxing in toluene, shaking, and leaving to cool. Presumably the terms >'sand' or 'powder' mean that the potassium will settle out. You seem to >be suggesting, however, that you can obtain an actual colloid this way. >Is that really so? (I understand 'colloid' to mean that the dispersion >is so fine that the solid does not settle out. I may need to be corrected >on this point). > I can't say for sure what the particle size of my metal dispersions was, especially since I was working with greases and therefore was not concerned with whether or not Brownian motion would keep the particles in suspension in a lower viscosity medium. I did, however, notice that the materials behaved much like the true micron and submicron water-in-oil (90% in 10%) explosive emulsions (based on aqueous ammonium nitrate/oil mixtures) with which I was familiar. Of course, I had the advantage of using relatively unreactive metals which coud interact passively with any surfactants which might already be present in grease. I wish I could offer you a more specific reference, but I recall that another patent issued in the same timeframe as mine (late '70s) on the general subject of metal-in-organic emulsions, not necessarily greases. The work in this patent was much more academic and thorough than my strictly practical formulation work. Although my patent preceded theirs, they had filed earlier and I felt that they had anticipated my work to a great enough extent to render the commercial value of my work doubtful, and I did not pursue the matter any farther than blending a few hundred pounds for field trials in an experimental bearing assembly being developed at the time. I would suggest that if you have any further interest in metal dispersions you might find that late '70s patent and read it for the more fundamental chemistry therin. If I stumble across my old records, I will email you the patent number and post it for others who may be interested in this corner of chemistry. Jerry DOC0104 Subject: Re: PH Question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/30 Message-ID: <422j9c$eaq@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <420pmj$4gd@geraldo.cc.utexas.edu>, glhurst@onr.com (Gerald L. Hurst) says: > > >pH = -log([hydronium]) = -log(10^-13) = 13 > >That's in theory. In practice the value will be somewhat higher. OOPS. "value" should read "value of the hydronium ion concentration" The absolute value of the pH will be somewhat lower than 13, not higher. To err is human to forgive humane, Jerry DOC0105 Subject: Re: PH Question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/30 Message-ID: <422j9c$eaq@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <420pmj$4gd@geraldo.cc.utexas.edu>, glhurst@onr.com (Gerald L. Hurst) says: > > >pH = -log([hydronium]) = -log(10^-13) = 13 > >That's in theory. In practice the value will be somewhat higher. OOPS. "value" should read "value of the hydronium ion concentration" The absolute value of the pH will be somewhat lower than 13, not higher. To err is human to forgive humane, Jerry DOC0106 Subject: Re: PH Question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/30 Message-ID: <420pmj$4gd@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <420mhm$ja1@news.scruz.net>, chad@rebellion.com (Chad Kunsman) says: > > >PH question: What is the PH of a .40 M aqueous solution of HNO3?? > I came up with .40PH where did I go wrong??? If HNO3 really did ionize 100 percent a pH value of 0.40 would be correct. In real life the value will be considerably higher. For purposes of a school exercise. 0.40 is fine. >PH question: What is the PH of a 0.050 M aqueous solution of barium > hydroxide??????? > I came up with 1.3 PH???? > > >Write the equations necessary to depict barium hydroxide dissociating >in water. > Br (OH) + HO------- H3BrOH + OH minus Is this close. > 2 2 Ba(OH)2 -> Ba(+2) + 2OH(-1) you can add "(aq)" to each species if you wish to make it clear that the species are in water. e.g. Ba(OH)2(aq) etc. In the following, the square brackets , [], indicate "concentration of" or "molarity of " whatever is between them. Since you get two hydroxyls for each mole of barium hydroxide, the concentration of OH(-) = [hydroxyl] = 2 X 0.050 = 0.1M or 10^-1 [hydroxyl] X [hydronium] = 10^-14 {equilibrium constant of water} (10^-1) X [hydronium] = 10^-14 [hydronium] = (10^-14)/(10^-1) = 10^-13 pH = -log([hydronium]) = -log(10^-13) = 13 That's in theory. In practice the value will be somewhat higher. You must have been doing something right to get 1.3 given that the digits are correct but you have a slipped decimal place. Remember that metal hydroxides are bases so we expect the pH to be above the neutral value of 7.0. Be sure to use a lower case "p" and an uppercase H lest people confuse you with a Ph.D :) Homework is lots of fun, eh? Jerry < DOC0107 Subject: Re: PH Question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/08/31 Message-ID: <423n5l$74t@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Keith Sheppard says: > >So when do concentrated strong acids become dilute? > >Is 6M HNO3 or HCl or H2SO4 concentrated or dilute? >and why? > They are neither concentrated nor dilute. These materials are not "concentrated" because they contain more water than the parent commercial materials which are generally acknowledged as "concentrated." The reasons for labeling an acid as "concentrated" vary from acid to acid. For H2SO4 it simply means nearly anhydrous material. Nitric acid is given that designation at ABOUT 68% (70%) because it forms a negative azeotrope at this level. Hydrchloric acid also has a negative azeotrope at about 20% but the commercial concentrated material is nearly twice this strong (38%), which represents about as much HCl vapor pressure as can reasonably be expected not to pop the cork. "Dilute" is a bit harder to define and one's notion thereof may be related to the applications one has in mind. For me acids are reasonably dilute when they effectively start behaving as mere hydronium ion sources which happen to be in the same solution with whatever anion. That is, oxidizing acids such as perchloric, nitric and to a lesser extent sulfuric stop behaving like oxidizers and dehydrating acids like H2SO4 and HF have their appetites for water more than satisfied. Another chemist might think it more appropriate to classify acids as dilute when there is enough water present to allow the activity of the hydronium ion to approach the apparent concentration. I suppose we all agree that a strong acid is truly dilute when it yields less than 10^-7 or so moles of hydronium ion per liter and many of us would be satisfied with 0.1 - 1M. However, when you're nitrating an unwilling molecule anything short of fuming HNO3 and H2SO4 can start to look dilute. Jerry DOC0108 Subject: Re: chemistry From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/01 Message-ID: <4263i9$qcm@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Lev Gorenstein says: > > >Well, well, guys... It's sad to say, but overall all the chemistry is >nothing more than physics of the outer electron shells... :-) > True. And life is nothing more than a sack full of chemicals. I suppose the physicists claim hegemony over the soul, it being made of phlogiston. Jerry DOC0109 Subject: Re: dumb question : water or ice - which denser? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/01 Message-ID: <427hci$oip@geraldo.cc.utexas.edu> Newsgroups: sci.physics,sci.chem In article <427h30$oip@geraldo.cc.utexas.edu>, glhurst@onr.com (Gerald L. Hurst) says: >As a child, I too was tought Rats, that one got away before I could change "tought" to "teached." Anybody got a spell checker macro for my return key? Jerry < DOC0110 Subject: Re: dumb question : water or ice - which denser? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/01 Message-ID: <427h30$oip@geraldo.cc.utexas.edu> Newsgroups: sci.physics,sci.chem In article , Anthony Potts says: > >The metal which was used to make type (in the good old days, when >I were a lad) also expanded when it froze. I do not know the >composition of the alloy, but it was necessary to have this >property so that the metal forced its way into the moulds >completely, to make printing neat and legible, without shitty >serifs or crappy qs. As a child, I too was tought that type metal, an antimony alloy, expands on solidifying. Many years later I read that this is not true but that the alloy merely has an exceptionally low degree of contraction on freezing. Does anybody here have any definitive numbers ? Jerry DOC0111 Subject: Re: dumb question : water or ice - which denser? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/02 Message-ID: <428ml3$hft@geraldo.cc.utexas.edu> Newsgroups: sci.physics,sci.chem In article <427mpb$6te@buffnet2.buffnet.net>, krieder@buffnet.net (Kurt Rieder) says: > >BTW... has anyone ever heard tin "cry"... or know what "tin cry" is ? > I have heard tin cry many times. I purchased several long narrow ingots of tin along with some bismuth and lead when I was making low melting alloys to emulsify in silicon oil to make dense grease. The tin rods were easily flexed and exhibited virtually no springiness but gave out a sound as though they were ratcheting into the new shape. No amount of bending back and forth seemed to weaken the metal or reduce its pronounced cry. It is a very impressive effect. Jerry DOC0112 Subject: Re: sucrose density From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/02 Message-ID: <428plq$hft@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <950902110624359@welcom.gen.nz>, jim.oliver@welcom.gen.nz (Jim Oliver) says: > >glhurst@onr.com (Gerald L. Hurst) wrote : >GLH>Subject: Re: sucrose density >GLH>The above exchange was followed by an email dialog > >I intensely dislike public postings of private mail content. This >has to be one of the worst abuses of Usenet. > >GLH>with Jim Oliver in which I continued to challenge >GLH>and he to defend the use of the principle of >GLH>Archimedes to measure the density of SOLUBLE solids. > >Nonense. Anyone still reading this knows that I conceeded in my >second public posting that only insoluble solids should be used >for the rough method I outlined. Otherwise use a suitable liquid >that won't dissolve the material being measured. > >I was moved to this concession after several friendly and helpful >posts in e-mail pointed out the potential problems. > Well gee, Jim, I'm sorry if you feel abused. I do apologize. I obviously misunderstood what you were saying. Silly me, I thought you were disagreeing and here all along you were on my side. Now, how are we going to convince Bruce Hamilton that you and I (we) are right? Unless, I misunderstand him too, he disagrees with the position we agree on. Jerry DOC0113 Subject: Re: FREON 12 Substitutes - Whadda ya know? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/03 Message-ID: <42d9iv$ig4@geraldo.cc.utexas.edu> Newsgroups: In article <42d42n$srp@mozo.cc.purdue.edu>, ghg@cidmac.ecn.purdue.edu (George Goble) says: > > >try this: Take a lit cigarette, and take a butane lighter, >push the button to release butane, but don't "flick" it >and try to see how hard it is to ignite using a lit >cigarette.. >--ghg > It is true that a cigaret will not ignite butane or any other alkane, but there are things under the hood that can, not to mention the flame that might be used to light the cigaret. Gasoline fumes around the engine can develop enough pressure on ignition to pop the hood up, which can be disconcerting to the driver and that same puff of energy can start a very destructive fire. Jerry DOC0114 Subject: Re: Help needed: Why is hydrogen floride toxic ? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/04 Message-ID: <42ft0p$8i8@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <42erkr$kgv@dub-news-svc-2.compuserve.com>, 70621.3462@compuserve.com (John S. Roberts) says: > >"Michael J. Shifflet" wrote: > >I've handled aqueous, liquid and gaseous hydrogen fluoride without getting a >burn. It itches like hydrogen chloride if you get it on your skin. > You have been very fortunate. HF burns are insidious and can be very severe, dangerous and extremely hard to heal. Anhydrous HF can char a wooden stick. Milder concentrations often at first only produce a slight discoloration of the skin, which is later followed by a rotting of tissue. I, too have been dosed many times with HF, but always got it off my skin in a matter of seconds because I have seen what it can do. Among the worst materials I have seen for destroying tissue are (NO2)2CFCH2OH and HgN(CF3)2. The skin goes through stages of green and purple putrefaction in an area many times greater than the original area of contact. In my next incarnation, I'm going to be a candy chemist. Jerry < DOC0115 Subject: Re: temp decrease in soda cans From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/06 Message-ID: <42j19r$fh8@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <42i3m8$oq1@geraldo.cc.utexas.edu>, Jason Ritchie says: > >In article Michael Gorsuch, explore@u.washington.edu writes: >>When the CO2 was held under pressure, the CO2 molecules must have been >>colliding more frequently with surrounding molecules. Wouldn't this >have >>made the can feel warmer than its surroundings when it was still closed? > > > Yes, but you then put it into your refrigerator or left it sitting >exposed to the atmosphere. There should be an increase in temperature as >you pressurize your soda, but it quickly equilibrates with the >surroundings. So when you open it all the "hot" CO2 molecules leave and >only the "cold" ones are left behind. This lowers the overall temperature >of the soda system. > >>from the fluid when the CO2 escapes. Where in the world is the "heat" >>that escapes? > This line of conversation assumes the original poster's statement that the temperature of a can of cold soda drops when the tab is popped. This idea may be correct in the absolute sense because the CO2 expands against the atmosphere thus losing a little heat energy by doing a bit of PV work and there is a subsequent slow cooling effect from the heat of vaporization of the CO2 as it gradually overcomes supersaturation and volatalizes. However this cooling effect is perhaps balanced or even outweighed by heat transfer from the experimenters hand, not to mention the heat generated by the mechanical action of popping the top. However, I doubt that either of these heat effects would be large enough to detected by the would-be imbiber. It's more likey that the perceived decrease in temperature arises from agitation by the thirsty scientist or the escaping bubbles which stir the inner, colder fluid around to the can surface thus creating the tactile illusion of overall temperature drop. Who will be the first to instrument sodapop cans so that we can quantify the temperature change and come up with an accurate table of Delta H(popatop)? Jerry DOC0116 Subject: Re: question re: freezing point depression From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/12 Message-ID: <434qls$9cs@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , eifel@interaccess.com (glen) says: > >The equation for freezing point depression is the following: > >delta Tf = kf * m > ^ ^ ^ > | | | > | | moles of solute particles/kg of solvent > | | > | molal freezing point depression constant > | > freezing point depression > >The Kf value for water is 1.86 (K kg / mol). > >In the CRC under "Concentrative Properties of Aqueous Solutions," there >appears values for delta Tf and m for various solutes. When I plotted a graph >to derive Kf for various solutes, I got values that differed from 1.86 (K kg / >mol). I realize that something like NaCl should give values roughly double >1.86, due to the fact that the NaCl dissolves completely. But, why would >something like ethylene glycol deviate from the 1.86 value. Is this due to the >dissociation of the alcohol groups in water? > Kf is only accurate if you use the "activity" or effective concentration of the solute rather than the actual concentration based on mass/volume. Activity is a sort of chemical excuse for the non-ideal behaviour of nearly all solutions except those which are very dilute. If you plot apparent Kf versus concentration and extrapolate the curve to zero concentration, you'll probably get answers closer to the 1.86 you're expecting. Jerry DOC0117 Subject: Re: [Q] cold trap From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/13 Message-ID: <4371f2$stb@geraldo.cc.utexas.edu> Newsgroups: bionet.parasitology,sci.chem,sci.chem.analytical In article , rose@alf1.ngate.uni-regensburg.de (Andreas Rose t3077) says: > >I study the host-finding of a blood-sucking bug (Reduviidae - Triatominae). >I want to collect odors from the headspace of a sleeping person and see >whether these are attractive in a behavioral test. > >For the collection of the odors, I want to construct a cold trap. [Snip] A dry ice-acetone trap should do the job. I would not use liquid nitrogen because it is cold enough to condense a trap full of liquid oxygen and solid CO2. Jerry DOC0118 Subject: Re: Aluminum plate to clean tarnish off silver works? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/15 Message-ID: <43ba0i$2ej@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <43b71e$etq@nnrp.ucs.ubc.ca>, dcwong@unixg.ubc.ca (Donald Chun Kit Wong) says: > >There's a product being advertised around. It's a metal plate. When one >puts it in a container water with Calgone in it, it's supposed to be able >to convert silver tarnish (and brass, too?) back to silver. Someone has >told me that it works, but another said it doesn't. I remember some type >of chemical reaction that does this from Chem lecture long ago. What is >the actual chemical reaction? Does anyone know if this metal plate >actually work? Thanks for any info. > You can get the effect with a sheet of aluminum foil immersed in water containing some dissolved sodium bicarbonate. The silver sulfide tarnish common on silver is reduced back to metallic silver. How well it works seems to depend on the exact nature of the tarnish - sometimes it works rather well, sometimes not. Jerry DOC0119 Subject: Re: Beginner's question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/15 Message-ID: <43cqdu$44a@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <43cbfg$mko@news.cerf.net>, Laura Weston says: > I think inorganic chemistry is easier and more intuitive than >organic chemistry. BUT there are millions of others that disagree. Millions? Everybody knows that that chemistry is merely a dumping ground for those who lack the intellect to become physicists. The descending order of minimum intelligence required to practice the chemical arts is: organic, inorganic, physical, analytical, management and quantum. In the greater scheme of things the major brain power hierarchy from top to bottom is: politician, lawyer, physicist, doctor, used car salesman, biologist, geologist, psychologist, sociologist, chemist and philatelist. Others may have different opinions, but they are wrong. Jerry DOC0120 Subject: Re: Beginner's question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/17 Message-ID: <43fofu$t7u@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <43f2e6$7ii@wizard.uark.edu>, cpuyear@comp.uark.edu (Charles S. Puyear) says: > >In article <43cqdu$44a@geraldo.cc.utexas.edu>, >Gerald L. Hurst wrote: >> >>Millions? Everybody knows that that chemistry is merely a dumping >>ground for those who lack the intellect to become physicists. > >You sir, are a pompous ass and an idiot to boot. By posting this kind of >nonsense you are merely broadcasting this fact to the world. > >>The descending order of minimum intelligence required to practice >>the chemical arts is: organic, inorganic, physical, analytical, >>management and quantum. > >As a theoretical (quantum) chemist, I am offended by your statement that >my field requires less intelligence of its practitioners than any of the >other chemical SCIENCES. (I think you listed them in an order opposite of that >which you intended, although I disagree with that also. It requires an extremely >clever mind to work in any area of chemistry.) Before you go shooting off >your mouth any more, I would suggest that you actually try your hand at >chemical research in any of the subdisciplines. You will probably find that >you are completely incapable of such work, and possibly realize (unless you >are even dumber than you sound) that you are too stupid to practice any >of the physical sciences, and that the scientific community can do without >any more of your moronic ravings. > ooOOPs! No wonder you're offended. I got my lists mixed up. The one you quoted does not correspond to descending intelligence, but to descending sense of humor. My second (unquoted) list of descending IQs, which terminated in "philatelist," has not yet drawn any irate responses from the stamp collectors. Perhaps they didn't take it seriously :( Jerry DOC0121 Subject: Re: MIT engineers; how they spend their time and how A@P From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/24 Message-ID: <4446kq$4rb@geraldo.cc.utexas.edu> Newsgroups: alt.sci.physics.plutonium,sci.physics,sci.physics.particle,sci.chem In article <443g7g$926@dartvax.dartmouth.edu>, Archimedes.Plutonium@dartmouth.edu (Archimedes Plutonium) says: > > Tell us what the total number of Coulomb Interactions there would be >for plutonium. I need this fact to plug into Debroglie's book. > Mr. Plutonium, please allow me the honor of providing that value so that you may continue your labours in the vinyard of physics. The value you are seeking is N!/2 where N is the total number of particles counting the nucleus as one particle, i.e. 11!/2 for neon. I leave the calculation for plutonium to you - it is obviously a rather large number. Jerry DOC0122 Subject: Re: nitrite to nitric oxide From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/24 Message-ID: <4444kc$4rb@geraldo.cc.utexas.edu> Newsgroups: sci.chem [More Headers] In article <441nub$fjo@news.asu.edu>, bridges@aztec.asu.edu (HARRY MOREL) says: > > >It has been found that bacteria on the back of the tong reduce >nitrate to nitrite. When the nitrite enters the anaerobic, acid >environment of the stomach, it is transformed into nitric oxide >and xxxx? > ..- ..- > :O: :O: > .. : .. bacteria .. : .. > O::N..O:- ------> O::N: + O: > .. + .. .. .. > ..- > :O: > .. : + acid .. . .. > O::N: + H ------> O::N: + .O..H > .. .. .. > >Could neutral OH be the correct answer? If it were, it would >further explain why bacteria are killed by this reaction. Could >someone please set the electrons right? Much appreciation for your >answer. Harry >-- Are you looking for the reaction 2HNO2 -> NO2 + NO + H2O ? Probably followed by 2NO + O2 -> 2NO2 from swallowed air. Either of the two free radicals (NO, NO2) from these reactions could probably kill bacteria. Jerry DOC0123 Subject: Re: Archimedes (was Re: Horst teaches . . .) From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/25 Message-ID: <445fcd$15b@geraldo.cc.utexas.edu> Newsgroups: alt.sci.physics.plutonium,sci.physics,sci.physics.particle,sci.chem In article <444ug1$isk@dartvax.dartmouth.edu>, Archimedes.Plutonium@dartmouth.edu (Archimedes Plutonium) says: > > So please tell roughly what the minimum Coulomb Interactions there >would be >for plutonium? I need this fact in order to plug into Debroglie's book. 95!/2, 5.16E147 Once again I say to you ninety-five factorial divided by two 516000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 0000000000000000000000000000000000000000000000000000 give or take a smidgeon. Jerry DOC0124 Subject: Re: WHO is MIT engineer Decobert's boss there at MIT? Govt From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/25 Message-ID: <445djg$15b@geraldo.cc.utexas.edu> Newsgroups: alt.sci.physics.plutonium,sci.physics,sci.physics.particle,sci.chem In article <444nl2$1ve@dartvax.dartmouth.edu>, Archimedes.Plutonium@dartmouth.edu (Archimedes Plutonium) says: > > Tell us roughly what the minimum Coulomb Interactions there would be >for plutonium? I need this fact to plug into Debroglie's book. > > The book LA THERMODYNAMIQUE DE LA PARTICULE ISOLEE (OU >THERMODYNAMIQUE >CACHEE DES PARTICULES) written by Debroglie, 1964 > > I need those Coulomb interactions to figure out the blackbody >temperature of an electron cavity of plutonium. > > So, Dirk, from Halliday and Resnick neon was computed at 2 x 10^7 but >please tell in your superior attitude what it is for plutonium? Mr. Plutonium, it is indeed a pleasure to be of assistance to a supergenius. To paraphrase my earlier posting, the value you seek to plug into de Broglie's work is 95!/2, which is about 5.16X10^147 (5.16E147). Now that you have the necessary datum, how hot is it? Jerry DOC0125 Subject: Re: Minimum Coulomb Interactions for plutonium From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/28 Message-ID: <44daq8$gh1@geraldo.cc.utexas.edu> Newsgroups: alt.sci.physics.plutonium,sci.physics,sci.physics.particle,sci.chem [More Headers] Article Segment 1 of 2 (Get All 2 Segments) In article <44cmbk$li3@dartvax.dartmouth.edu>, Archimedes.Plutonium@dartmouth.edu (Archimedes Plutonium) says: > >In article <448tro$e6g@rzsun02.rrz.uni-hamburg.de> >fc3a501@AMRISC04.math.uni-hamburg.de (Hauke Reddmann) writes: > >> May I add a little bit? As I am familiar with quantum chemistry >> computation, the fact that there are so much interactions is >> somewhat irrelevant. When you express the Coulomb interaction >> in the "Slater determinant" picture, you reduce the whole stuff >> to just two sorts of operators: 1-electron and 2-electron op's. >> And in fact, even for an actinide like plutonium, the whole >> interaction can be expressed in simply three adjustable >> parameters. > > Hauke, thanks, you appear to be a sort of my own guardian angel of >sorts. > > Halliday and Resnick say that neon has a minimum of 2 x 10^7 >independent pairs of charges whose Coulomb interactions must be taken >into account. >----------- > <11MAY199412262849@csa5.lbl.gov> Scott I Chase and Thomas S. Zemanian ><ts_zemanian-110594082225@ts_zemanian.pnl.gov> both said it was N x >(N-1)/2 or 20 x 19/2 = 190. > And this answer of 190 is what several physics professors here at >Dartmouth gave me as an answer and it seems to be the most preferred >answer by physics professors -- 190 for neon. But I do not like it for >I believe by instinct, by intuition that no atom of neon with 10 >protons and 10 electrons can hold-up with just 190 things going on. >------------ > But, another poster says this. In article ><447olq$mj4@ux.accesscom.net> >jim.goodman@accesscom.net (Jim Goodman) writes: > >> >For n particles, there are (n 2) two body interactions. >> (n 2) = n!/(2!x(n-2)!), best I can do with a typewriter. >> see <http://www.accesscom.net/sawf/> >----------- > And another poster says this. In article ><4446kq$4rb@geraldo.cc.utexas.edu> >glhurst@onr.com (Gerald L. Hurst) writes: > >> Mr. Plutonium, please allow me the honor of providing that >> value so that you may continue your labours in the vinyard >> of physics. The value you are seeking is N!/2 where N is >> the total number of particles counting the nucleus as one >> particle, i.e. 11!/2 for neon. I leave the calculation for >> plutonium to you - it is obviously a rather large number. >----------- > > And I said this in 1994, that the reason for 2 x 10^7 for neon was >because of the four quantum numbers (n, L, M_L, m_s) such that for neon >it is (2^20 x2 x 2 x2) > >----------- > > So, who is correct and more important how do you get your answer, >explain it? Please just do not give a formula for so many people now >have given so widely different answers. I want to know the why and >wherefor also so that I can be sure of the Coulomb for plutonium. Is >plutonium (188 x 187)/2 or 95!/2 or 2^188 x 2x2x2? Here I repeat >Halliday and Resnick's orginal. > >PHYSICS, part 2, extended version, 3rd edition 1986, Halliday & Resnick > >pages 1190-1191 > >ATOMS BEYOND HYDROGEN. At the beginning of this chapter we described >how the hydrogen atom potential energy function (Eq. 51-1) is inserted >into the Schroedinger equation and how that equation can be solved to >yield quantum numbers and wave functions. All of our results so far, >then, apply to the hydrogen atom only. What about other atoms? > For atoms with substantially more than one electron the potential >energy function that we must substitute into the Schroedinger equation >involves the Coulomb interaction between many pairs of particles and >can rapidly become hopelessly complicated. In neon, for example, it can >be shown that, including the nucleus and the ten electrons, there are >no fewer than about 2 x 10^7 independent pairs of charges whose Coulomb >interactions must be taken into account if the Schroedinger equation is >to be solved rigorously. At this level of complexity rigorous solutions >are not possible, and we must rely on methods that are both approximate >and numerical. >--- end of quoting Halliday & Resnick --- DOC0126 Subject: Re: Minimum Coulomb Interactions for plutonium From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/28 Message-ID: <44daq8$gh1@geraldo.cc.utexas.edu> Article Segment 2 of 2 (Get Previous Segment) (Get All 2 Segments) Mr. Plutonium, I am partly responsible for the confusion here. There are a number of ways of looking at the interactions of particles in an atom, but if we are here looking for the number of distinct pairs with coulombic interaction then it would not be 2 x 10^7 but N(N+1)/2 where N is either 11 or twenty for neon, depending on whether you count the nucleus as one charged particle or as 10 particles (protons). Although the N(N-1)/2 figure looks rather small compared to the full factorial numbers which describe the number of permutations of particle strings (or sequences) involving all the particles (or better, their states), remember that it only refers to COULOMBIC interactions, not to all interactions. Anyway, the coulombic pair interaction number for plutonium is either 95(95-1)/2 or 188(188-1)/2 depending on the viewpoint. I suspect that the Halliday & Resnick chapter erred in using the 2 x 10^7 figure for the number of binary coulombic interactions. Jerry DOC0127 Subject: Re: ALUMINUM BOMB From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/30 Message-ID: <44iqdc$d77@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.engr.mech,sci.physics In article , emilsson@aries.scs.uiuc.edu (Tryggvi Emilsson) says: > >tims@megtas.lsid.hp.com (Tim Shipe) writes: > >The oxide film on Al is pretty tough. It is one of the metals recomended >for use with fluorine.I once passed some fluorine gas over a scoop of aluminum >powder.Nothing happened.I tried the same treatment on other materials.Magnesium >powder,silicon carbide,Teflon,most any organics,and even GLASS ,ignited or >exploded on contact. > When I was developing a synthesis for N2F2, I had to prepare cold traps with a layer of AlCl3 sublimed onto the inner surface. I made the salt by reacting Cl2 with thin Al foil heated in the glass trap with a hot air blower. Under these conditions the aluminum stays bright for a prolonged period of time until the chlorine finds the first chink in its Al2O3 armor, after which the reaction procedes at great speed. In pilot plant production, I always handled fluorine in monel or stainless steel systems with a bit of copper here and there, but much of this work was at moderately high temperatures (200 C) and high pressure (2400 psi). I never considered aluminum. I wonder if it would withstand this environment? Kinda makes me shudder to consider Al in contact with the ClF5 we were making at the time, but who knows? Jerry DOC0128 Subject: Re: question!!!!! From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/09/30 Message-ID: <44ioh5$d77@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , dreynold@chat.carleton.ca (Derek Reynolds) says: > > >What is the difference between the terms > >Adsorb.....and.....Absorb? > Substances are adsorbed ONTO the surfaces of other materials but are absorbed INTO other materials. A monomolecular layer of water on steel is said to be "adsorbed" whereas the moisture in a typical fabric, i.e. cotton or Nylon, is largely absorbed inside the fibers as indicated by the swelling of the latter. Jerry DOC0129 Subject: Re: Impact of chemistry on philosophy? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/03 Message-ID: <44qnl8$mei@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <44pc3l$f9f@lunen.gac.edu>, mmenge@pepperoncini.gac.edu (Matthew P Menge) says: > > I was wondering if chemistry has made any impact on philosophy. >Physics and biology, for instance have both made impacts on philosophy. >In biology there was the theory of evolution, for instance, and in physics >there was the theory of relativity, among others. > I am neither historian nor philosopher, but it seem to me that the concept of entropy, arising from chemical thermodynamics and the consequential view of time as an arrow rather than a (classical physicist's) pendulum, has an ongoing influence on philosophical thought or at least it does when I'm in my armchair thinking up long rambling sentences. Jerry DOC0130 Subject: Re: what is flash point? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/03 Message-ID: <44qp8c$mei@geraldo.cc.utexas.edu> Newsgroups: sci.engr.chem,sci.chem In article <44pivb$5b9@news.nd.edu>, ruiyun wu says: > >dear netters: > >can anyone tell me how flash point is defined? and how can I figure out the >flammibility from it? > >And by the way, do you think n-decane (as solvent) under 100C and 1 atomsphere >is dangerous? The flash point is the lowest temperature at which the equilibrium vapor above a liquid in air will ignite in the presence of a spark or flame. In other words if a liquid is at or above its flash point in, say, an ashtray and you wave a burning match over it a few millimeters from the surface, the vapor will flash. There is a second, higher temperature called the fire point, which is the minimum temperature at which a liquid will continue to sustain combustion of its vapor once ignited. In other words, if the liquid in your ashtray is perhaps 20 degrees above its flash point, the vapor will not merely flash, but continue to burn. Remember that the concept of fire point only works for pools of liquid. If the liquid is wicked into a fibrous material, the difference between the flash point and the fire point becomes vanishingly small. N-decane has a flash point of 46 deg C. Therefore, the vapor above the liquid is susceptible to ignition at that temperature or above. A spark of 0.3 millijoule (not much) is enough to ignite it. In the U.S, the term "flammable" usually means that the substance being described has a flash point below 100 deg F (37.8 deg C). N-decane would be considered "combustible" at least with respect to normal ambient conditions and it would be so labeled for shipping. Jerry DOC0131 Subject: Re: what is flash point? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/07 Message-ID: <456gs5$826@geraldo.cc.utexas.edu> Newsgroups: sci.engr.chem,sci.chem In article <456aa6$hqp@steel.interlog.com>, RFalkiner says: >there are several ASTM ISO etc tests for measureing flash point > >it roughly coincides with the LEL lower explosive limit > >for hydrocarbons How rough is the coincidence and why is it rough? Jerry DOC0132 Subject: Re: definition of isodesmic??? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/08 Message-ID: <457rm2$73v@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , vsummers@polaris.cv.nrao.edu (Vince Summers) says: > >As I have been informed...isodesmic is the approximation of a >structure by considering energies of `equivalent' pieces. Ex. a >benzene is equivalent to 2 H3C=CH-CH3 groups minus 8 -H bonds from a >methane. >That is if no resonance or other properties were involved. Thus you >can >determine roughly resonance, etc. Someone else may put this more >succinctly. >Vincewq > I really don't know about such stuff, but it would seem to me that benzene's energy would be more like that of three H3C-C(H)=CH-CH3 molecules minus the energy of three ethane molecules with the difference in energies being largely a function of what we used to be allowed to call resonance energy before the quiche and trail mix-eating quantum physics guys made it non OC (orbitally correct). Anyhoo, I would like to know if it is CC (chemically correct) to call the above method ) an "isodesmic" operation or approximation. I've been doing this sort of thing in the closet for years, not knowing that it had a name and that I was not alone :) Jerry DOC0133 Subject: Re: what is flash point? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/08 Message-ID: <457g53$so7@geraldo.cc.utexas.edu> Newsgroups: sci.engr.chem,sci.chem In article <4572i1$n36@steel.interlog.com>, RFalkiner says: > >glhurst@onr.com (Gerald L. Hurst) wrote: >> >> In article <456aa6$hqp@steel.interlog.com>, RFalkiner >> says: >> >> >there are several ASTM ISO etc tests for measureing flash point >> > >> >it roughly coincides with the LEL lower explosive limit >> > >> >for hydrocarbons >> >> How rough is the coincidence and why is it rough? >> >They are essentially the same thing, but the answer you get depends somewhat >on the hardware configuration used in each particular test. > >you have to think of flash point as a "benchmark" type of test. it >represents the temperature where the equilibrium vapour of a liquid becomes >"flammable or explosive" under normal conditions. Then under "normal" conditions the may be said to coincide exactly. One could argue for mixtures that the flash point is actually a continuous series of values which varies as the mix evaporates, whereas the LEL represents the lowest vapor concentration, having the same molecular ratio of non-air components as the parent condensed phase, that will flash. On the other hand, it can be argued that such a value would be pretty much worthless in the real world where the partial vapor pressures of mixture components may span several orders of magnitude. Sounds like F.P. and LEL probably coincide nicely for pure compounds but have a less intimate relationship for mixtures. Jerry DOC0134 Subject: Re: what is flash point? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/10 Message-ID: <45d9r8$s6u@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <895849388wnr@fats.demon.co.uk>, Richard Bettis says: > >Flash point is temperature measurement >LEL is concentration measurement > >little coincidence there! Certainly, there is. Thunder and lightning are not the same thing but they do tend to coincide. Of course it might be said that it is no mere coincidence that the flash point and the LEL coincide with each other under certain circumstances. Jerry DOC0135 Subject: Re: what is flash point? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/10 Message-ID: <45d9ap$s6u@geraldo.cc.utexas.edu> Newsgroups: sci.engr.chem,sci.chem In article <45bhfp$fde@zephyr.grace.cri.nz>, B.Hamilton@irl.cri.nz (Bruce Hamilton) says: > >glhurst@onr.com (Gerald L. Hurst) wrote: [snip] >>Then under "normal" conditions they [Flash point and LEL] may be >>said to coincide exactly. > >Definitely not. > >There are a wide variety of Flash Point procedures, [snip] There are indeed, but not all of them would be really very "normal" considering we were discussing the original poster's parameters, which referred to equilibrium vapor, i.e. closed cup run infinitely slowly or thereabouts. >>One could argue for mixtures that the flash point is actually >>a continuous series of values which varies as the mix >>evaporates. > >Flash Point is just that. [snip] > I'm glad I got it right:) Jerry DOC0136 Subject: Re: what is flash point? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/12 Message-ID: <45i1bq$4b0@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <479783410wnr@fats.demon.co.uk>, Richard Bettis says: > >> Thunder and lightning are not the same thing >> but they do tend to coincide. Of course it might be said that it >> is no mere coincidence that the flash point and the LEL coincide >> with each other under certain circumstances. >> >> Jerry >> >OK. There is a coincidence. I'm pleased you see it. >Is there any coincidence between brighter lightning >and brighter thunder? Or louder lightning and louder thunder? Hmm. I am unaware that there is any such thing as bright thunder or loud lightning except in some allegorical sense. I suppose there may be some incidence of coincidence between loud thunder and bright lightning, but you'd have to ask a meteorologist. >Just because two >things happen at the same time, even for the same reason, doesn't mean >they are >the same thing. I'm pleased with your paraphrase of my first sentence above. >If you corner a car too fast, the tyres screech. However, if you make a >screeching noise, your car doesn't turn. These observations suggest that there is probably a relationship between the screeching of the tires (tyres) and the cornering but no apparent relationship between the tires and my voice. The cornering and the tire screech seem to have same sort of relationship as lightning and thunder, i.e. the latter does not cause the former, and, although they are related to each other they are not related to my voice. >All I'm saying is that you *cannot* compare temperatures with concentrations. That sounds reasonable, but you CAN compare incidences of two things (coincidences) that regularly happen at the same temperature such as a vapour reaching its LEL and its flash point simultaneously. The vapour flashes, inter alia, because it has reached its LEL just as loud thunder peals because the bright lightning bolt has just struck. Thus in each case the two phenomena are different but coincide. >The two are not related at all! > Ahh. But if the flash point and the LEL are not related at all, then it must be a COINCIDENCE that they seem to occur at the same temperature. Jerry DOC0137 Subject: Re: Nitrogen Triiodide From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/13 Message-ID: <45klb3$979@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <45jhcn$55g@pulp.ucs.ualberta.ca>, dabell@gpu.srv.ualberta.ca (Darcy Abell) says: > >Phred PSmIth, Galactic Gadabout wrote: > >>Not that NH4I3 is that stable. One would get a big pile of damp ammonia >>triiodide in the filter, but getting it to wait while it all dried out >>would never work: it would just explode in small bits as it dried out. > >This is not the case. If it is left alone while drying you can dry a >substantial amount. Once it is dry, it will go off VERY easily >though. How stable the clump is depends alot on how finely divided >the iodine was. I believe you folks are talking about nitrogen triiodide, NI3:xNH3 rather than ammonium triiodide, NH4I3. The latter is relatively stable whereas the former is a very sensitive primary explosive. Jerry DOC0138 Subject: Re: H2O Bridges From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/16 Message-ID: <45sm9h$cgj@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <45sfm2$8l4@vixen.cso.uiuc.edu>, misterc@ux7.cso.uiuc.edu (Christopher Clayton) says: > >syed shah writes: > >>Does anybody know of compounds with bridging water molecules? > > What about polymerized water? I heard about that a couple of years >ago...fascinating topic! ;) > Oh, yeah, polywater, the stuff they use in cold fusion cells to generate the phlogiston. Jerry DOC0139 Subject: Re: Hints on building a freeze dryer From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/25 Message-ID: <46koq2$a9c@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.physics,sci.cryonics In article <46itn4$8id@ixnews3.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: > . Vacuum gas conductance varies as the fourth power of tubing >diameter. Think about it.) > Can you, please, explain why the conductance varies so much with diameter in a reasonably good vacuum? Jerry DOC0140 Subject: Re: Where did the MOLE come from? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/25 Message-ID: <46ks3h$a9c@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <5BAnAzl.tinkerbelle@delphi.com>, Kimberly Lewis says: > >Ok--what Ireally meant to say was why did they name it the "mole" ? I >know where it came from + stuff..just not why it's called that =) > Don't you suspect that they shortened the phrase "(mole)cular weight." Or better yet, "The weight of a compound numerically equal to its (mole)cular weight or at least its empirical formula weight expressed in whatever units my country and/or discipline have decided are standard." More succinctly put, the term "mole" is short for "stone (mole)cular weight," with the various values being based on the standard mole of carbon, i.e. 12 stone (168lbs). Stone units are particularly useful for calculating reaction rates because a rate of one stone molecular weight (mole) per fortnight is precisely equivalent to one pound of carbon per day if you happen to be reacting carbon. Obviously, many countries which were conquered by Napoleon now use other systems of measurement, and there is nothing wrong with their continuing to do so, if they wish, providing we remember that, although the Teutonic fortnight also has forteen days (Heute in vierzehn Tagen), their weeks are 8 days long (Heute in acht Tagen). Those of you who have mastered 18th century apothecary weight systems will have no trouble converting moles per fortnight into units of kilograms per Germanic week, in case you need to communicate with a chemist in, say, Austerlitz. Jerry DOC0141 Subject: Re: Weighing metals (Jason) From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/26 Message-ID: <46netd$5hp@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <46n1jm$3ps@nnrp2.news.primenet.com>, mattstr@primenet.com (Matt Strandberg) says: > >You're going to have to learn to use your resources better, if you want >to succeed in Chemistry...use your periodic table! >it has the atomic mass number right on it...and you do mean "mass"; weight >is gravitational pull; mass remains constant. :) > Oh, I don't know. A lot of otherwise pretty sharp chemists use the terms "molecular weight," equivalent weight," and "atomic weight" when they are conducting experiments here on planet earth. Sometimes they will even be heard to utter phrases like "This sample of unknown metal has a weight of exactly one gram," but we wiser heads know that the proper wording is "This sample of metal exerts a force of 981 dynes on the pan of the balance." Actually there is absolutely nothing wrong with letting force and mass be equal numerically. We just have to agree that in Dr. Newton's "F=MA" one gram of force accelerates one gram of mass at 981 cm/sec^2. Sheesh, speaking of weight, I need to get away from this computer and shed a few poundals or slugs or whatever. Jerry DOC0142 Subject: Re: Chemistry Problem..(Please help!) From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/28 Message-ID: <46sip9$mop@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <46sat0$9t1@news2.isp.net>, Al Oyafuso says: > >Hi! I am currently REALLY stuck on this problem. Can someone help me >out ASAP? Anyone info will be gretly appreciated. I also need to be >shown how the problem was solved. Thanx a great deal. > >Problem: > You find an unknown metal. It's mass is 218.413 grams. You place >this metal in a large beaker of water and heat the water to boiling. >Let teh water stay boiling for about 10 minutes. In the meantime, >measure out 500.0 grams of new water and pour it into a styrofoam cup. >You find that its temperature is 22.3 degrees Celcius. You now take the >hot metal and quickly remove it from the hot water and put it in the >water in the styrofoam. The temperature of the "styro" water rises >until it reaches 38.9 degrees Celcius. It then starts getting cooler >again and then eventually returns to 22.3 degrees Celcius. Using this >data, calculate the Specific Heat of the metal. > Sounds dangerous to me. With a heat capacity that high it's probably an alloy of beryllium and lithium and you shouldn't be dunking it in hot water. (specific heat of metal) * (mass of metal) * (change in temp. of metal) equals minus (specific heat of water) * (mass of water) * (change in temp. of water) I'll bet you didn't read your book. Jerry DOC0143 Subject: Re: Hot Water From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/29 Message-ID: <470vvl$dsr@geraldo.cc.utexas.edu> Newsgroups: sci.chem Article Segment 1 of 2 In article <4707k4$eva@ixnews5.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: > >Dear Tom, > >The question was trivial. Art lies in finding hidden assumptions and >ramming them down a TA's throat. Given the ACS goal of 30% "minority" >degree conferral (not 30% more, 30% absolute!), and the unemployment rate >among new BS grantees at 70% in 1994... I would not even hallucinate >hiring a generator of "gentleman's Cs." I want the most extreme, >meanest, toughest, most recreative nerds, propellerheads, and rocket >scientists. I want the most powerful mentalities. I want labs filled >with alpha geeks. If management cannot herd cats, we get better >management. > >Haven't you ever done a bomb calorimetry experiment? The answer requires >correcting for heat lost to the environment, typically by calculating the >power input to hold waterbath constant temperature by an electric heater, >and extrapolating forward. > >Remember - diamonds can only be synthesized at extreme high pressure and >temperature. It is irrefutably proven in every elementary physical >chemistry text. A number of companies are making a few $hundred million >every year because some socially crippled ouch bag with an IQ hovering in >the stratosphere realized the hidden assumption of "at equilibrium." CVD >growth of diamond does not take place at equilibrium. > >Mediocrity is a vice of the doomed. > Uncle Al, you have a point, but it might be better made if you quoted a few lines to let us know from what source and by what route your inspiration flowed. I'll bet you are referring indirectly to the post which began: >>Problem: >> You find an unknown metal. It's mass is 218.413 grams. You place >>this metal in a large beaker of water and heat the water to boiling. >>Let teh water stay boiling for about 10 minutes. In the meantime, >>measure out 500.0 grams of new water and pour it into a styrofoam cup. >>You find that its temperature is 22.3 degrees Celcius. You now take the >>hot metal and quickly remove it from the hot water and put it in the >>water in the styrofoam. The temperature of the "styro" water rises >>until it reaches 38.9 degrees Celcius. It then starts getting cooler >>again and then eventually returns to 22.3 degrees Celcius. Using this >>data, calculate the Specific Heat of the metal. >> Although it is obvious that the kid is looking for someone to do his homework, we might do better in the long run with a reply like this: The metal starts out at 100 deg C because it is coming out of boiling water. The water in the cup starts out at room temperature, 22.3 deg C. They both change temperature and both wind up at about 38.9 deg C at least in the short term before the whole assembly slowly cools down to room temp again. If you were looking for really great accuracy, you would measure the temperature of the cup/water/metal against time as it cooled down to room temperature, plot the data on graph paper and extrapolate back to the instant you plunked the metal into the cup. If you were to do this, you would find that the temperature was in fact slightly higher than the 38.9 deg you've quoted. Since you did not mention any other data, I will assume that your teacher is not expecting you to work with this slightly more accurate value and just go on with the 38.9 deg you have specified. The metal goes from 100 deg to 38.9 so the change is 100-38.9=-61.1 deg The water goes from 22.3 deg to 38.9 so its change is 38.9-22.3=16.6 deg Water has a specific heat of very nearly 1.00 cal/deg/g (that is calories per degree per gram). Therefore, the number of calories absorbed by the water from the metal is 16.6deg*500g*1.00cal/deg/g = 8,300cal The amount of heat lost by the metal must equal the heat gained by the water so we can use the same equation we used for the water, except that we substitute X for the unknown specific heat of the metal and use the appropriate values for the temperature change and the weight of the metal. 61.1deg*218.413g*X = 8,300cal DOC0144 Subject: Re: Hot Water From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/29 Message-ID: <470vvl$dsr@geraldo.cc.utexas.edu> Article Segment 2 of 2 Solving for X gives: X = 8,300cal/61.1deg/218.413g = 0.622cal/deg/g This answer would be a little bit low because it does not take into account the heat capacity of the styrofaom cup or the loss of heat during the time between the immersion of the metal and the measurement of the temperature of the temporarily more or less equilibrated mixture. Only a metal or alloy with a very low average atomic weight would have such a high specific heat. I personally don't find the question "trivial." It merely reflects a level of education most Ph.D.s passed through early on their long path to underemployment :) Jerry DOC0145 Subject: Re: QUESTION: (bio)chemistry of popcorn From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/29 Message-ID: <46up8d$635@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <46qf0n$5aa@wn1.sci.kun.nl>, jasperf@sci.kun.nl (Jasper Faber) says: > > >Can anybody tell me what the (bio)chemistry op popping corn >is. Why is the process so fierce? What is happening? Is >popping also possible with other kinds, like rice or wheat? > I'll leave it to others to tell you that popcorn pops because the shell retains water until it yields under the increasing vapor pressure of the entrained water allowing the softened, hydrolyzed starch/water composition to expand suddenly and solidify as the superheated water flashes and cools the mixture. But I can say that there ARE other poppable grains such as milo. Jerry DOC0146 Subject: Re: Where did the MOLE come from? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/29 Message-ID: <470tvr$dsr@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4705ea$6a9@news.isbe.state.il.us>, Tom Dearing says: > >>A much more important question would be, >>why is the abbreviation for mole mol?? >>Who in their right mind thought this would save time, ink, paper etc. >>Does anyone know of another equally silly abbrev. only one letter less than >>the full word? > >I agree with this one! Anytime I'm working problems involving moles I just can't >quit when I get to the l and the **** e slips in on me. This gives me a terrible >complex about not being a legitimate chemistry teacher and giving my students the >incorrect symbol. Oh well I guess that is something I'll have to deal with. >-- The first people to use the the word that sounds like "mole" were Germans. They abbreviated "Molekuel" in shuch a way as to retain the long o sound in their language, and "Mol" did the trick very nicely. They couldn't possibly have used the spelling "Mole" because the Germans have nothing to do with mexican dishes and they certainly did not want to feminize the abbreviation for a neuter word. Back in those turn-of-the-century days we English speaking people were still metaphorically swinging from in the chemical trees babbling "combining weight" when this laconic Teutonic triumph occurred. The first translator had a hard choice to make: to retain the form or the sound of the new term. He knew that most Brits and Amis would frown at anything that wasn't some sort of alcohol ending in "ol." He probably surmised that the british might use a long "o' like the Germans, but he also reasoned that the Americans would balk and blurt out a sound like "moll" with all its unscientific connotations and invitations to double entendre. Finally, he considered the fact that the Americans were the sort of people who mispronounce and misspell good German words like "Wolfram" so badly that they come out "tungsten." and, with, a stroke, he wrote "mole," thus preserving a semblance of the sound if not the form of the original utterance. If you find yourself on the edge of schizophrenia using "mole" when you think you should be typing "mol," just throw in a few other foreign mots like "Gestalt" and "Weltanschauung" and your readers will simply think you are terribly erudite, but patriotic. Jerry DOC0147 Subject: Re: thermochemistry question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/29 Message-ID: <46v3cc$dc9@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <46umko$37n@hopi.dtcc.edu>, m6337@hopi.dtcc.edu (CHRISTOPHER M. MALINOWSKI) says: > >Please help me! >I'm really stuck on this one problem, if anyone could please email an >answer directly I'd greatly appreciate it. >Here it is: > >Given the following data: > H2 (g) + .5 O2 (g) => H2O (l) > change in H = -285.8 kJ > N2O (g) + H2O (l) => 2HNO3 (l) > change in H = -76.6 kJ > .5 N2 (g) + 1.5 H2 (g) +> HNO3 (l) > change in H = -174.1 kJ >Calculate the change in H for the reaction: >2N2 (g) + 5 O2 (g) => 2N2O5 (g) > Your equations are nonsense. If you expect to have anyone help you with your homework, at least have the courtesy to spend enough time to present the questions and data accurately. Jerry DOC0148 Subject: Re: thermochemistry question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/30 Message-ID: <471l6n$5fs@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <470ki9$5vq@zippy.cais.net>, alchemst@pacificnet.net (John Milligan) says: > >In article <46umko$37n@hopi.dtcc.edu>, > m6337@hopi.dtcc.edu (CHRISTOPHER M. MALINOWSKI) wrote: >>Please help me! >>I'm really stuck on this one problem, if anyone could please email an >>answer directly I'd greatly appreciate it. >>Here it is: >> >>Given the following data: >> H2 (g) + .5 O2 (g) => H2O (l) >> change in H = -285.8 kJ >> N2O (g) + H2O (l) => 2HNO3 (l) >> change in H = -76.6 kJ >> .5 N2 (g) + 1.5 H2 (g) +> HNO3 (l) >> change in H = -174.1 kJ >>Calculate the change in H for the reaction: >>2N2 (g) + 5 O2 (g) => 2N2O5 (g) >> >>The section this falls under the "Hess's Law" chapter in _Chemistry_ in >>Zumdahl. I have the answer (it's in the back of the book), but I just >>don't know how to do the problem. >> >>Thanks in advance! >>Mal >> >Since the other responses were of little or no use, I'll give you a hint. You >need to find a way to add the correct equations, which I assume are in your >book, to get the final equation. The way in which you add the first three is >the way you add the delta H's to get the enthalpy change for the last >equation. > >The correct equations are: > > H2 + 1/2 O2 ---> H2O dH = -285.8 kJ > > N2O5 + H20 ---> 2 HNO3 dH = -76.6 kJ > > 1/2 N2 + 3/2 O2 + 1/2 H2 ---> HNO3 dH = -174.1 kJ > >Reaction is > > 2 N2 + 5O2 ---> 2 N2O5 dH = ??? > >Keep in mind that if you reverse an equation that its dH changes sign. If you >multiply an equation by a number the dH gets multiplied by the same number. > >Hope this helps. > It's terribly nice of you to help the youngsters copy their equations from the book to the computer and it is even nicer that you fill in the blanks where they have left out information. I really don't know what equations they were given, but based on real life reactions and the hints given in the original post, I surmise that they were, or should have been given equivalent, but less convenient multiples of the following rather commonly known reactions 1. 6H2 + 3O2 -->6 H2O 2. 2 N2 + 6H2 --> 4NH3 3. 4NH3 + 8O2 --> 4 HNO3 + 4H2O 4. 2N2O5 + 2 H2O --> 4 HNO3 Add 2 and 3, then subtrct 1 and 4 and rearrange to get: 5. 2N2 + 5O2 --> 2N2O5 DOC0149 Subject: Re:solubility of gasses in liquids:QUESTION From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/10/30 Message-ID: <471ri0$5fs@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , todda@coral.indstate.edu says: > >If gasses are more solubile in liquids at lower temperatures why does the >carbon dioxide dissolved in any carbonated drink come out when it is poured >over ice. It is getting colder so the carbon dioxide should become more >solubile not less solubile. Colder or not, the CO2 is still supersaturated in solution and the ice provides nucleation points where that gas can expand. Try to imagine the mechanism of expansion in the absence of nucleation sites. The CO2 molecules would have to randomly collide to first form molecular scale bubblets which would have to grow by diffusion from the liquid until they were large enough to generate Brownian motion-defeating lift. Long before they reached this size, the enormous surface pressure of the submicroscopic bubbles would drive the gas back into solution. In this world, if you're a bubble, you gotta be big to survive and in order to get big you've got to nucleate. Jerry DOC0150 Subject: Re: *so* sorry and glad From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/03 Message-ID: <47bsch$8as@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <478cr5$cct@hopi.dtcc.edu>, m6337@hopi.dtcc.edu (CHRISTOPHER M. MALINOWSKI) says: > >First of all I'd like to thank the people who took the time to help me >with the thermochemistry problem I put on here about a week ago. >Secondly I'd like to thank the people who decided to flame me about >the problem I put on because it was missing a variable which anyone with >even the slightest amount of brain power could fill in, that is if they >weren't too busy chastizing someone and trying to teach them some >ill-begotten lesson. The reason I'm thanking them, is because if I do >decide to become a chemist I will not want to end up like them. >Thanks again! >Mal > >-- >"Those who forget history are doomed to repeat" Gasp!!! I was shocked to learn that someone in this forum had the gall to actually CHASTIZE a teenager for one tiny little mistake in copying his homework assignment onto the net. If I were you I would immediately contact the ACS and file a formal complaint. BTW, was the single "variable" you missed the "5" in N2O5 or the missing "O2" in the equation for producing nitric acid from the elements, or are you referring to the incorrect coefficient for hydrogen in the same, unbalanced and incomplete reaction, or are you simply referring to the general imbalance of two of the equations? I suspect that many chemists in this forum have forgotten how difficult and time consuming it is to copy a couple of equations from a textbook such as: 0.5N2 + 0.5H2 + 1.5O2 --> HNO3 and N2O5 + H2O --> 2HNO3 without wasting valuable time in checking all those boring coefficients and subscripts. The very next time you are faced with such a problem and don't have the time or inclination to work the thermodynamics out for yourself, just log onto sci.chem and type: N + H --> HNO NO + HO --> HNO And let somebody else sort out the details:) Jerry Those who do not dot their i and cross their t are full of sh?? < DOC0151 Subject: Re: Copper + Silver nitrate-----> *Please Help* From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/03 Message-ID: <47dm5p$eia@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <47cadl$soq@ixnews7.ix.netcom.com>, e-mail@ix.netcom.com (None ) says: > > > Hi, > I know this question is probable very simple and a waste of >your time but please humor me and write back. The reaction 'copper + >silver nitrate ----> Silver + copper nitrate[Cu(NO3)2].' In this >reaction silver is produced but this silver is in an impure form. >Can anyone tell me what impuraties are in the silver, how they got >there, and most importently how to remove the impuraties. > Thanks for your help, sorry about the spelling errors. > Please tell us how you know that the silver is impure. Jerry DOC0152 Subject: Re: Additive to make paint glow From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/04 Message-ID: <47f61g$glu@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <47eher$3bo@supreme.pcug.org.au>, Thomas Huljev says: > >Can anyone help me with this. The classic pigment is zinc sulfide doped with a little copper salt. Don't grind the material too fine. Jerry DOC0153 Subject: Re: exothermic reactions From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/04 Message-ID: <47f5jq$glu@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <47dp23$f3g@dim.intersurf.net>, smiller@intersurf.com (Scott Miller) says: > >glhurst@onr.com (Gerald L. Hurst) wrote: > >>In article <47bqup$djq@numbat.devetwa.edu.au>, Clinton Smith says: >>> >>>i would like to demonstrate an exothermic reaction: >>>would potassium permangante and glycerine be appropriate for a small >>>experiment? >>> >>Why not just strike a match or flick your Bic? > >>Jerry > > >Um, that would be combustion, huh? > >Yeah it's exothermic, but it's also destructive. > >My lab students always get a kick out of dissolving NaOH pellets >(although that's a pretty caustic reaction). > >Scott I see, you don't like combustion because it is "destructive." By that I assume you mean you'd like something a little less exothermic, a bit more reversible and not too caustic. OK, have your students make little plaster of Paris balls. They can dehydrate them in an oven at a modest 130 deg C then let them cool in a jar. When a drop or two of water is added to a ball it will warm up noticeably and the balls can later be recycled by heating. You might add a bit of cobalt chloride to the balls so that you get the blue-pink color change along with the harmless thermal effect. I have another demo in which the balls turn incandescent but, sigh, it's destructive. > Jerry DOC0154 Subject: Re: Endothermic Reaction From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/05 Message-ID: <47j9cq$4cb@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <47j14h$2bd@mozo.cc.purdue.edu>, Brian says: > >Hey everyone... > >I had a question. Does anyone have an idea for an endo thermic reaction >that uses easily obtainable reactants. Basically what I need this for is >to cool some ni-cad batteries I use in RC vehicles. The reaction would >have to be contained in an enclosed bag or capsule. If the reaction you >have in mind produces some gas and therefore cannot be contained in a >sealed container, this would also be OK. Most importantly though, the >reactants or products shouldn't be toxic or harmful. ANY ideas on this >would be greatly appreciated. Thanks for your time. > You might try ammonium nitrate and water. The dissolution of AN in water absorbs a great deal of heat. The combination is often packaged and sold for use as an emergency cold pak. AN is cheap, but you can recover the solid by simply evaporating the water whenever the relative humidity is below about 60% or otherwise by warming the solution. Jerry DOC0155 Subject: Re: thermochemistry question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/06 Message-ID: <47m6p9$q02@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , bosse@met.kth.se (Bo Sundman) says: >Anyone who knows how N2O5 is actually produced (if it is ...) > It is made by dehydrating nitric acid with P2O5. It exists in two solid forms and can be distilled under rather extraordinary conditions. The equation N2 + 5/2O2 --> N2O5 is merely the formal, if hypothetical reaction associated with the heat of formation of the compound. Jerry < DOC0156 Subject: Re: Dancing mothballs? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/07 Message-ID: <47ohel$gep@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <47o23d$34v@curly.cc.emory.edu>, nmukund@curly.cc.emory.edu (Nancy E Mukundan) says: > >I, also, learned that the active ingredient in mothballs >is naphthalene. Recently, someone told me it is some >other compound, but I don't recall what that is. Anyone >know about this? > p-dichlorobenzene, as I recall. Jerry DOC0157 Subject: Re: sodium hypochlorite (bleach) and organic impurities? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/09 Message-ID: <47scb7$c01@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <1995Nov9.054656.7280@galileo.cc.rochester.edu>, gl002c@uhura.cc.rochester.edu (G. Lane) says: > >I believe (don't ask for a balanced reaction) that sodium hypochlorate >(chlorox bleach, an important chemical in the industrial revolution) acts >as a solid and portable form of chlorine, or in general just oxidizes very >well. The solidity of sodium hypochlorite is somewhat questionable. The Industrial Revolution may have to settle for an aqueous solution. > living things don't like getting oxidized, and tend not to survive. This is particularly true of rapid oxidation above about 500 deg C. Jerry DOC0158 Subject: Re: Caloric Value From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/13 Message-ID: <4864ci$40f@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.engr.chem In article <481to6$1da$1@mhade.production.compuserve.com>, Johan Reynaert <101353.3201@CompuServe.COM> says: > >Hi, > >Who can explain to me the difference between the higher and lower >caloric value of natural gas. > Natural gas from different sources contains varying amounts of such gases as ethane, CO2, nitrogen, and even helium. Increased amounts of ethane raise the volumetric caloric content while the other gases reduce it by simple dilution. Jerry DOC0159 Subject: Re: Coulombic forces From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/13 Message-ID: <486j27$cgd@geraldo.cc.utexas.edu> Newsgroups: sci.chem . > >The inverse square law applies for two point charges. The >inverse first power law applies for the force between two >infinite parallel plates (I believe then that the charges >are those on each of the parallel plates). > What rule applies to two parallel charged lines? Jerry DOC0160 Subject: Re: delta H question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/13 Message-ID: <486tqa$gm6@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <486soq$gm6@geraldo.cc.utexas.edu>, glhurst@onr.com (Gerald L. Hurst) says: > then another 540 cal/mole to change the water >to steam. OOoops. I meant to say 540 cal/g times 18g/mole or roughly 9720 cal/mole to change water to steam. Never believe the numbers we post, just pray the principles are half right :) Jerry DOC0161 Subject: Re: delta H question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/13 Message-ID: <486soq$gm6@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <486ifg$3dh@madeline.INS.CWRU.Edu>, Robert Kanar says: > >hello, i am a student in a first year chem course in college and my >professor posed this question, which we are supposed to find the solution >to "any way we can." i was wondering if anyone here could please help me >with it. > >"How would one find the delta-H of a reaction if the reactants are at 25 >degrees C and the products are at 100 degrees C ?" > >we have a chart that has the values of the delta-H-of-formations at >standard states, and the basic formulas, but no one knows how to deal with >the variation of the temperature. i'm guessing that calculus is involved >somehow, could someone please explain? thanks !! > >You simply need to use heat capacity data to calculate the amount of energy it takes to raise the temperature of the reaction products from 25 to 100 degrees, plus any heat required for phase changes. If the product were water at 100.1 deg C and atmospheric pressure, it would take 18 calories/deg/mol times (100 - 25)deg to get the liquid up to the 100 mark, then another 540 cal/mole to change the water to steam and then a tiny amount to heat the steam 0.1 deg. (Cp, the heat capacity of steam, times moles of steam times 0.1 deg) Thus the total change in enthalpy would be the original value for the standard reaction plus the three quantities we just calculated for each mole of water. The same principle applies for whatever products and whatever phase changes may occur in warming up your products. You won't need calculus this time, because you are dealing with a small temperature range and the heat capacities can be considered as constants. When you deal with larger temperature ranges, get ready to use those tall esses. Notice that we use Cp, the heat capacity at constant pressure rather than Cv, the heat capacity at constant volume. We do this so that we don't have to correct our energy values for the PV change that occurs when we heat our materials. That's why it's so convenient to talk about total enthalpy change rather than total energy change. Jerry DOC0162 Subject: Re: odor of acetamide? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/14 Message-ID: <489dcv$c88@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <488geh$af1@brahms.udel.edu>, sunrise@brahms.udel.edu (Adam Le Halberstadt) says: > >Can anyone out there tell me what acetamide smells like?I have a >bottle of acetamide crystals that smell like glacial acetic acid. >However, the merck index states that acetamide when pure has no odor, and >has a mousy odor whem impure. Is this acetamide contaminated, or is the >label wrong? Thanks for your help. > I remeber my first whiff of slightly impure acetamide 40 years ago quite well. The odor was, indeed faintly like that of a mouse nest - nothing more. Yup, I've smelled it since then, and it hasn't changed. Acetamide does hydrolyze to acetic acid (or a salt thereof) in the presence of acid or base, but the reaction is usually described as occurring in hot water. Jerry DOC0163 Subject: Re: Quiz question - please help From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/16 Message-ID: <48eplb$3e2@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <48e4ht$d1p@news.nsysu.edu.tw>, "Robert M. A. Hsu" says: > >afelton@ix.netcom.com (Andy Felton) wrote: >>On 14 Nov 1995 21:25:29 GMT, iaotb@inet.uni-c.dk (Torsten Brinch) >>wrote: >> >>>Lubosh.Hanuska (ljh655@anugpo.anu.edu.au) wrote: >>>: This must be a trivial question for those who know a bit (not like me) about >>>: chemistry: >>>: What is the common name of NaCl ? >>> >>>:-) >>>This is just ordinary tears (dry). >>> >>>Seriously: NaCl = salt >>> > Just to clear up any confusion, any binary compound with a metal as one >of the elements is a salt (is this correct?). > > >Not really. >As I know, SALT is defined as compounds whose aqueous solutions have >conductivity. For example, NH4Cl is a salt but it's not binary and >without a metal. However, Fe2O3 is a binary compound and with a metal >but never considered as a SALT. >That's what I know. > It might be better to think of a salt as an ionic compound which can be formally thought of as the product a reaction between an acid and and a base with the elimination of water. Ammonium chloride, for instance, might be be formed by the reaction NH3 + HCl --> NH4Cl, but we consider it the salt of the hypothetical reaction NH4OH + HCl --> NH4Cl + H2O. You might then consider Fe2O3, not as a salt but a base, or in its hydrated form as either an acid or a base. Keep in mind that these concepts are matters of convenience for chemists. The properties of a metal oxide are not inherently distinct from those of materials we more readily refer to as "salts." This particular view is widespread because we tend to orient our thinking around the protonic theory of acids for routine work-a-day chemistry. Jerry DOC0164 Subject: Re: Quiz question - please help From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/16 Message-ID: <48gaou$sin@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <30AB5E68.5FB3@esvax.dnet.dupont.com>, John Kirchstein says: > >The common name for NaCl is Halite --- This is the mineral rock >salt. I believe the more common name for NaCl is "table salt." Jerry DOC0165 Subject: Re: Liquid Paper Solvent From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/20 Message-ID: <48on45$qqn@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <48nq32$ovd@muss.CIS.McMaster.CA>, u9301134@muss.cis.McMaster.CA (C. Base) says: > > >Could anyone tell me what the solvent in Gillette's Liquid Paper(tm) is? >It used to say 1,1,1-trichloroethane on the label, but now all they say is >that a Material Safety Data Sheet is available (in Canada, at least). To >the average Tom, Dick, and Harry, this is useless. Is it still Cl3C-CH3? >-- I'm the guy who put the 111 in Liquid Paper, but the general formulations anticipated later switching to other materials in case 111 was found to have unanticipated problems. If I knew what they are using, I couldn't tell, but I don't so I'll surmise that it is an HFC - that's what I would use :) Jerry DOC0166 Subject: Re: Question... From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/20 Message-ID: <48om37$qqn@geraldo.cc.utexas.edu> Newsgroups: sci.chem X-Newsreader: WinVN 0.92.6+ In article <48i9n5$3qr@news.ysu.edu>, av256@yfn.ysu.edu (Brian Travers) says: > > >I would greatly appreciate it if one of you kind folks could help me out... > >Question: I make water "hard". My solubility in water decreases >as the temperature increases. I am found on the bottom of >your teapots. I am also used as an antacid. What compound am I? > I think the questioner is perhaps a little mixed up. CaSO4 is known for its unusual decreasing solubility with increasing temperature, at least at moderately elevated temperatures. However, it is CaCO3 which is an antacid, but, as far as I know, the solubility of this material increases slightly with temperature. I suppose CaCO3 might appear less soluble because of possible formation from the more soluble bicarbonate in hot water. Any of these calcium salts impart the quality of "hardness" to water. Jerry DOC0167 Subject: Re: U-In8: First Commercial Cold Fusion Cell? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/21 Message-ID: <48s25k$ov3@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <48r28u$1f9@ixnews3.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: [re yet another cold fusion breakthru] >I'll give you 100-1 odds against, just after I liquidate in my mortgage >equity and life savings, and you put up 1% in escrow, with a deadline. > >At 10,000-1 odds it would would still be, in the words of science fiction >novelist Frank Herbert, "a Wreave bet." > Uncle Al, I think you're on to something here. The only problem is figuring out how to convince the indefinitely expectant true believers. They will keep it "on the verge" of success long after other religions have given up waiting for their respective Messiahs. Jerry DOC0168 Subject: Re: Swallow Me From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/22 Message-ID: <4904ou$i3p@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <744677514wnr@fats.demon.co.uk>, Richard Bettis says: > >caesium (this is the correct spelling, perhaps Americans don't use the 'a' >because they feel that 'a' is unservicable - as in u/s of a) > >from the Latin: caesius, blue-grey. (as in the colour of Caesium) > >(presumably Chemists find this hilarious, they've got to get their kicks within >their limitations I suppose) > Americans spell cesium as they please. They capitalize "USA," but not "Chemist" or "Cesium." You may presume what you wish, but I doubt that many chemists or chemical engineers here or in the UK find any humor in the ingestion of any alkali metal. It IS interesting to note that the thread caught your attention and led you to comment on American spelling and your impression of the nature of chemists' humor. If you wish to become an American chemist, you can go back to school and pick up a few courses prior to emigrating. You could also continue your studies in the USA, but you might be required to pass an English language proficiency test before being accepted into graduate school. Judging from your few lines of prose. it would appear that you could pass with flying colors after a little study and practice. Jerry < DOC0169 Subject: Re: Swallow Me From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/24 Message-ID: <493d0u$n2k@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , ch3106@irix.bris.ac.uk (J. Spashett) says: > >PS On spelling I don't care how people spell stuff. > >But what I *hate* is being told by IUPAC that I have to spell Sulphur as >Sulfur. I mean come on! > Yeah, but I really draw the line at "Fosforus" and "fenolfthalein." According to IUPAS (International Union of Pure and Applied Semantics), the correct spelling of "IUPAC" is "UICAP" because adjectives should follow nouns. Actually, the word-order rule-making organization recently renamed itself "UISAP" for obvious reasons. The Germanische Union fuer die Reinigung der Muttersprache (GURM) and the Union fuer die sofortige Hinauswerfung von verdammten Fremdwoertern und weitere Reinigung der Germanischen Sprachen (USHVFWRGS) have objected to the implementation of rules based on Romantic language constructions. Jerry < DOC0170 Subject: Re: Swallow Me From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/24 Message-ID: <495eso$spd@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <735613793wnr@fats.demon.co.uk>, Richard Bettis says: > >After all, even Americans can get into graduate school (well, American graduate >schools at least.) >> >> Jerry > >(shouldn't that be Gerry?) >> Some of them get into Cambridge. Gerry DOC0171 Subject: Re: Air Fuel Mixture Ionization From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/11/29 Message-ID: <49gvhi$sdt@geraldo.cc.utexas.edu> Newsgroups: sci.chem,alt.engr.explosives In article <49fbks$fl1@cobia.gulf.net>, Chuck Thigpen says: > >I am in no way a chemist. However, I am a mechanical engineer looking >to find a way to ionize an air & fuel mixture using electricity. Would >it be possible to ionize this mixture using an electromagnetic field? >Or am I just out to lunch. What other ways could I ionize this mixture? >Thank you. > You will have no problem getting the mix to ionize at low pressures. A Tesla discharge against a glass tube of the materials will do the job. However, at any pressure, your fuel and oxidizer won't take long to react with one another, probably explosively. You could say that the sparkplugs in your car ionize fuel/air mixtures at least in the vicinity of the electrodes. There have been some gadgets on the market which claim to preionize fuel/air in cars or to create a "corona" effect. I knew a mechanical engineer who strapped one on his car and believed he derived better milage from that P.T. Barnum device. "Positive ion" generators were also very popular at one time. I knew a fellow , who had one in his horse trailer and one in the cab of his pickup. He was sure they made both himself and the horse run faster. In fact, he was so convinced about the merits of these "pizza pans on a stick" that he boasted openly about how he had conned the unsuspecting inventor out of the patent rights for a measley $20K. Hmm. Come to remember, this was the same guy who also prided himself for having relieved another gullible inventor of a priceless piece of technology for another $20K. This time it was a system for cleaning up oil spills by sprinkling radioactive powder on them so they'd polymerize. Once the slick was solidified, you could just roll it up. I guess this also involved ionization. I always thought I, too, should have let myself be cheated out of one of my great inventions, but somehoe I never got around to it. If you're sure you want to ionize fuel/oil mixtures, give me a call :) Jerry DOC0172 Subject: Re: Bubbling in soda. From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/02 Message-ID: <49p2nn$i1l@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , jvinson@rmci.net (John W. Vinson) says: > >dwilkins@northernnet.com (Don Wilkins) wrote: >>For the benefit of Mr. Vinson. I would like to offer a short Bavarian >>poem. For him I think it is particularly appropriate. > > >> Fuer d'Flöh gibts a Pulver >> fuer d'Schuach gibts a Wix >> fuer'n Durst gibts a Wasser >> bloss fuer d'dummheit gibts nix >> (anon.aus Bayern) > > >True true... a rough translation: > >For the flu give a powder >For the (shower?) give a (raincoat?) < not in my Cassell's; Beyrich? >For a thirst give some water >But for stupidity, there's nowt! >John W. Vinson --------------------- 74222.2372@compuserve.com >Wysard of Information Scientific Information Consultant > Greek scholars disagree - why shouldn't we? For fleas there's a powder for shoes there's a polish For thirst there's water But for stupidity there's naught The attribution to Bavaria is absurd. No Bayer would think of water for thirst, at least never in a Schnaderhuepferl. Jerry DOC0173 Subject: Re: Bubbling in soda. From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/05 Message-ID: <4a0av0$dbd@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Michael Newmen says: > I do have a question though about the responsibility of chemists >in a world all to eager to use chemicals. I recently saw a list of >instructions on how to make exploasives, timing devices, and how to use >them. Tell me, at what point to we have to draw the line between the >free exchange of information and censoring that which is dangerous to >society? One sees a lot of explosive "recipes" on the usenet, but I doubt that many of them are posted by chemists. Most of the garbage appears to be infinitely recycled methods which drift farther from reality as successive generations of wannabe teenybombers add their personal inexperience. Jerry DOC0174 Subject: Re: Chemie und deutsch From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/17 Message-ID: <4b1s7q$ll1@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4aunpa$qrd@due.unit.no>, Martin Ystenes says: > >tice@nai.net (Bradley D. Tice) wrote: >>German was easy to learn. The basic words are very similiar to English. >>And there's only twelve ways to say "the." > >der, die, des, den, dem, > >Where are the 7 others? > Der has 4 applications: feminine and plural possesive, dative feminine, nominative masculine; die has 2: feminine and plural; des has 2: dative masculine and neuter; den (2) may be dative plural or accusative masculine and dem (2) is either dative masculine or dative neuter. That makes twelve. There are arguably fewer or more depending on one's viewpoint. For instance "die" could be said to be 3 kinds of nominative plural. I counted it as only one since the rule is easily remembered. I would guess that having five words representing 12 concepts might be harder on the student than 12 differently spelled words. I suppose this is a question that might be more easily answered by a first-year German student. Jerry (Ico) DOC0175 Subject: Re: SEMTEX - what is it? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/19 Message-ID: <4b537i$k9@geraldo.cc.utexas.edu> Newsgroups: sci.chem,alt.engr.explosives In article <4b4pf4$qnp@bcarh8ab.bnr.ca>, yshan@bnr.ca (Yogi Shan) says: > >I find it strange that PETN would be mixed with >RDX. _Plastique_ is _plastique_. RDX (the >explosive in C4), I understand is more expensive >than PETN, and would require a separate >production line. > You are right, Yogi. PETN and RDX are so similar in their explosive properties that it would be foolish to mix the two and thereby double the risk of some chemical incompatibility unique to one or the other. By coincidence, it happens that I have prepared and tested plastic explosives that have about the same composition as the material that is now called "Semtex." The compositions are very similar to C-4 in look, feel and performance. In the US, RDX has been viewed as a "military" explosive. PETN, was considered more as a "commercial" explosive, partly because of its private industrial manufacture and widespread use in detonating cord. RDX, of course, works just as well in det cord and is the basis for the military version. Industrial use of RDX is mostly limited to surplus powder which is cast into primers in admixture with TNT.. If you ask US military folks why they use RDX rather than PETN, they will usually cite the somewhat lower density and greater sensitivity of PETN. Besides, it's a habit and it costs the taxpayer more :) Jerry (Ico) DOC0176 Subject: Re: Freezing hot water From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/20 Message-ID: <4b7s4o$76i@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4b7pil$fnu@usenet.ucs.indiana.edu>, "John C. Huffman" says: > >hhowe@trgnet.com (Harold Howe) wrote: >>Why does hot water freeze faster than cold? >> >>Harold Howe >Actually it doesn't. Water with disolved gases will freeze at >a lower temperature however, and hot water will contain fewer >disolved gasses. Therefore, the hot water may appear to >freeze faster, especially if the freezer is only a few >degrees below 0C. I believe that the freezing point depression by dissolved air is considerably less than 1/100 deg C, which would not seem likely to make a noticeable difference in the freezing rate with a temperature differential of a few degrees. Jerry (Ico) DOC0177 Subject: Re: Freezing hot water From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/20 Message-ID: <4b7q6p$76i@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4b7jri$sk8@insosf1.netins.net>, hhowe@trgnet.com (Harold Howe) says: > >Why does hot water freeze faster than cold? > I've never actually encountered frozen hot water - it was always been quite cold :) Perhaps you mean to ask why initially hot water in an ice-cube tray sometimes freezes before a similar tray of cold water under the same conditions. In some cases, when there is a substantial layer of frost on the metal conducting heat to the evaporation coils, the warmer tray melts the layer away and allows the tray to contact the very cold and highly thermally conductive metal. Removing the frost layer is like opening a door for the heat to move through by conduction. Once the thermal barrier is gone, the water which was warmer up to about that point rapidly becomes colder than the initially cold water which continues to rest on umelted frost and therefore loses heat more slowly. Jerry (Ico) DOC0178 Subject: Re: SEMTEX - what is it? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/21 Message-ID: <4baa9h$bk5@geraldo.cc.utexas.edu> Newsgroups: sci.chem,alt.engr.explosives Article Segment 1 of 4 In article , B.Hamilton@irl.cri.nz (Bruce Hamilton) says: > >In article <4b537i$k9@geraldo.cc.utexas.edu> > glhurst@onr.com (Gerald L. Hurst) writes: >>In article <...>, yshan@bnr.ca (Yogi Shan) says: >[ my earlier cite to C&EN, noting that Semtex had > both RDX and PETN deleted ] >>>I find it strange that PETN would be mixed with >>>RDX. >... >>You are right, Yogi. PETN and RDX are so similar in their explosive >>properties that it would be foolish to mix the two and thereby >>double the risk of some chemical incompatibility unique to one or >>the other. > >>By coincidence, it happens that I have prepared and tested plastic >>explosives that have about the same composition as the material that >>is now called "Semtex." The compositions are very similar to >>C-4 in look, feel and performance. > >Well, as promised, I looked it up. Experience tends to make me >very suspicious of Gerald's assertions :-).... > >From:- "Analysis of Semtex Explosives" J.R.Hobbs. >Chapter 39. p.409-428 in " Advances in Analysis and >Detection of Explosives" edited by Jehuda Yinon >Kluwer Academic Publishers ISBN 0-7923-2138-3 (1993) > >Table 1. Summary of Semtex Analysis > >Name Semtex H Semtex A >% PETN 49.8 94.3 >% RDX 50.2 5.7 >Dye Sudan I Sudan IV >Antioxidant N-phenyl-2- N--phenyl-2- > naphthalamine naphthalamine >Plasticizer n-octyl phthalate n-octyl phthalate > butyl citrate butyl citrate >Binder styrene-butadiene styrene-butadiene > rubber rubber > >Table 2. Gravimentric Analysis >Sample size 1.0194 1.1061 >Weight oil 0.0811 0.0994 >% oil by weight 7.9 9.0 >weight rubber 0.0920 0.1036 >% rubber by we DOC0179 Subject: Re: SEMTEX - what is it? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/21 Message-ID: <4baa9h$bk5@geraldo.cc.utexas.edu> Article Segment 2 of 4 ight 9.0 9.4 >weight explosives 0.7029 0.7029 >[ rest of table omitted ] > >Note that other chapters highlight the fact that Semtex H was the >explosive used in mainland UK. There is an excellent, droll >chapter " The Semtex H Story" by A.W.Feraday,OBE - head of >Forensic Investigations, Forensic explosives Laboratory. He >describes all 58 incidents involving Semtex, and notes they killed >284 ( of which 270 were at Lockerbie, and 11 at the Deal barracks), >whereas 3288 incidents involving other explosives killed 107. He >was emphasising that Semtex is not unusual. In one " own goal " >in a car three terrorists were putting the finishing touches to a >300 ball bearing / 85gram Semtex claymore mine intended to >disrupt an anti-Khomani meeting, when it exploded. The driver's >surname was Fooladi, :-) - he was the only survivor, 10 years at >her Majesty's pleasure... He also notes the various names of >the manufacturer - initially the Semtin Glass Works, then the >Eastern Bohemian Chemical Works, then Synthesia. > >Another paper also notes that ICAO have insisted that volatile >taggants be added to involatile plastic explosives at manufacture, >and EGDN ( ethylene glycol dinitrate ) is now added to Semtex H. >Several papers also note that various batches contain various >levels of impurities and compositions, but all consider Semtex H >to have a minimum of 21.5% RDX and a maximum of 64.5% PETN >with around 14% of rubber and oil. There are a couple that note >that Semtex A1 is predominantly PETN, but as the above analysis >indicates it still has both, although I suppose some people may >ignore the few % of RDX. I've no idea of the relative volumes, but >th4e above articles indicate that H was the common terrorist >material of concern > >I will add bits of this to the FAQ, with the reference. I suspect >the earlier reference I cited may be more comprehensive ( and >it's the same author ), but it's not accessible to me. > > Bruce Hamilton > Bruce and I have indeed had our discussions in the past regarding a minor difference of opinion about the suitability of using the principle of Archimedes to measure the density of very water-soluble solid materials. Bruce may like to tell you which side of that argument he supported. So, we have found some analyses of materials said to be "Semtex-X" that contained anywhere from 21 to 64 percent PETN with the balance RDX and inerts. You don't suppose these could be the result of the extreme financial problems in the old eastern block, especially in the period 1993? The Russians and Poles, etc are very good at the science of high explosives so they know that it is unwise to specify the unessary use of two components in an explosive mix where one will do. Not only does it increase the likelyhood of chemical incompatibility, but it puts your manufacturers in the position of having to carry double inventories, which is a hell of a stupid thing to do when you are dealing with national defense. We have already discussed the fact that there is little difference in the performance of plastique made from RDX or PETN. I suspect that the Semtex being glommed onto by terrorists is a kitchen sink material made up of whatever proportions of HEX types they can find. If comrade Vladimir gets Col Khadaffi's order for a few tons of plastique, and Vlad finds he is out of PETN from the Chernobyl plant, does he apologize and not fill the order because he doesn't have the "minimum" 21 percent PETN? Or does he simply manufacture "Semtex U," short for USA, a material remarkably like C-4? As long as these guys can get their hands on either PETN or RDX individually or in a mixed ordnance scrap pile, they will continue to manufacture "Semtex" and people will continue to ask "What is the composition of Semtex?" I would be willing to bet that there is plastique "Semtex" out there adulterated with TNT, HMX (They should be so lucky) and tetryl as well and probably a good bit of it cut with inerts to the cap-sensitivity limit.. DOC0180 Subject: Re: SEMTEX - what is it? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/21 Message-ID: <4baa9h$bk5@geraldo.cc.utexas.edu> Article Segment 3 of 4 According to your gravimetric analysis table II, the total explosive contents of Semtex "A1" and "H" respectively are 64 and 69%. The corresponding oil/rubber contents are 17 and 18% for totals of about 81 and 87%. Based on the ratios in table 1, the RDX woiuld be 5.7*.64 = 3.6 percent which is far less than the material not accounted for. Three or four percent sounds like an amount which can be assigned to residue from not cleaning the mixer between batches. There is not a great deal of difference in the explosive performance of RDX and PETN, but there are valid military reasons to prefer the former (sensitivity, stability). There are are also good reasons to use PETN in commercial applications - it is powerful and cheap. Now, the old Eastern Block's ordnance was second to none in those areas where they had the necessary skills, and they definitely knew at least as much about explosives as we do. Most explosives chemists are very used to the idea of interchanging RDX and PETN in various commercial formulations depending on the price of the materials. In this country we use RDX for primers when the government deigns to sell off old surplus material. If I had an order for 1000 1lb 50% cast primers, but only 250 lbs each of RDX and PETN do you suppose I would make up two batches of 500 lbs each or one batch of 1000 lbs. Regardless what went in, the customer would probably think of it as "pentolite." For the quarry operator, no harm done, but Uncle Sam wouldn't buy it. A military formulator, whether here or in Poland would not make a plastic explosive from PETN if he/she had access to ample RDX unless the object was to save money, in which case he/she would simply use PETN. The use of a PETN/RDX mixture would be an expedient measure when supplies were short and the customer was desperate or not too particular, as in the case of Middle East terrorists. Adding 5% RDX to a PETN formulation would produce undetectable performance changes, but it would make good sense if you had some surplus RDX available, commercial access to all the PETN your rubles can buy and willing buyers other than your own fussy military. Note that the analyses indicate an excessively high proportion of inert materials, way beyond the less than 10% required to impart adequate plasticity. Looks like somebody has their thumb on the scale, doesn't it? Or do you suppose the Eastern armies don't object to carrying around a little totally useless baggage in combat? It is more likely that the high inert values are a reflection of the fact that terrorists will buy anything that goes "boom" most of the time. I understand that they are giving away a free sample of "red mercury' with each case of Semtex. Perhaps we can have a debate about the precise composition of the former sometime. For those of you who like pigeon holes and lables, we could make a sliding scale for "Semtex" formulations using all the letters of the alphabet to designate closely the percentages of RDX as a function of total explosive content and number designators to represent the percentage of inerts. On a ternary graph this would produce a large area of compositions with a single dot on the RDX/inert axis labled "Semtex C-4." Should you ever need to order some Semtex for a demolition job, be sure to nudge the salesman and tell him you want the good stuff. Else what you get will be just about any composition up to, but not including C-4 or Detasheet. Bruce admonishes: >Experience tends to make me very suspicious of Gerald's >assertions :-).... Bruce does a lot very good work in providing an excellent chemistry FAQ and he knows more about gasoline than any three other chemists I've met. If he says my assertions are suspicious, he is probably right, especially if he knows as much about military explosives as he does about hydrocarbon mixtures. < DOC0181 Subject: Re: SEMTEX - what is it? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/21 Message-ID: <4baa9h$bk5@geraldo.cc.utexas.edu> Article Segment 4 of 4 All I know is what I picked up walking by the door where the smarter guys were discussing explosives. Bruce is much more academically inclined than I am. The result may be that he sees "Semtex" as a necessary specifier for a poorly defined continuum of formulations with sub-classifications "A" and "H" which are also indefinite compositions. My relatively non-academic brain revolts at this concept and insists that there really isn't any such thing as "Semtex" except insofar as we choose to use the term for any plastique which is analyzably not C-4 or C-3. Of course, there may be an "original Semtex" which actually had a specific composition. If there was, then what we need is the original official spec sheet, not an analysis of something we found in a bomb at the embassy. I have this dream in which they find a brief case bomb containing a plastic explosive which is not C-4. Analysis shows it to be form of Semtex. I read the analysis and realize that it is material I made 20 years before "Semtex" was invented and that was left in some long-abandoned storage magazine which has fallen into the wrong hands. I keep my mouth shut. One of the doors I passed in the old days belonged to Israeli security people. They invited me in, touched a pea-sized ball of dynamite to my palm and then showed me how their detection instruments went wild in the vicinity of my subsequently cleaned hand. This was a truly impressive demonstration of their ability to detect the EGDN used in nearly all dynamites. It would not surprise me at all if they and others fearing terrorist attacks wished EGDN into the formulations as an easy way to make them detectable with existing equipment. If I were selling such equipment, I might be tempted to lobby for rules requiring the addition of EGDN to plastique, but I'd hate to have to manufacture the material. Is EGDN addition really a good Idea? I don't think so. EGDN is chemically and physically unstable compared with any military explosive and it is a vasco-dilator that can put you in the hospital if you handle it too much as in molding a plastic explosive. In this country we have gotten rid of all our NG/EGDN explosives plants save one for good reasons. Who now wants to actually manufacture and transport EGDN purely for use as a taggant? Those who sell off the shelf dynamite detectors, of course - now that terrorists are unlikely to use dynamite. Mind you, all I know is what I heard walking by the doors and my perspective on matters such as explosives nomenclature and acceptable formulations may be warped by too little time spent in the library and too much spent in the hallways. Jerry (Ico) What do you get when you combine a gram of Semtex, a gram of red mercury and a gram of polywater in a cold fusion apparatus? A lot of hot air. DOC0182 Subject: Re: calcium carbonate in iron pipes question From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/21 Message-ID: <4bb2c6$ra@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , moroney@world.std.com (Michael Moroney) says: > >In article <4b7m1n$lea@news.asu.edu>, >bridges@aztec.asu.edu (HARRY MOREL) wrote: >> >> Why does a white substance (calcium carbonate?) deposit on the >> inside of iron pipes over the years? Why doesn*t the calcium, (or >> magnesium) carbonate remain dissolved in the water? > >If you're talking about hot water pipes, calcium carbonate, unlike most >chemicals, is less soluable in hot water than it is in cold. > >There may also be a reaction where calcium bicarbonate reacts to form >calcium carbonate, CO2 and water, the CO2 either escapes or reacts with >iron to form its carbonate, and the calcium carbonate precipitates. >I am unsure about this last part. > I seem to recall it being calcium sulfate which has decreasing solubility with rising temperature, at least for high water temperatures. Also, I believe that the observed modest solubility of calcium carbonate is mostly due to the formation of bicarbonate by CO2 in equilibrium with air. Upon heating, the CO2 concentration is lowered with the result that calcium carbonate precipitates giving the illusion of a negative temperature coefficient of solubility. Jerry (Ico) *Experience tends to make me very suspicious of Gerald's assertions :-)* --Bruce Hamilton DOC0183 Subject: Re: Thermal decomp of Ammon Phosphate ? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/23 Message-ID: <4bfu3s$2pt@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4bf0e2$4re@cloner2.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: > >pietervk@vub.vub.ac.be (Pieter Vankeerberghen) wrote: >> >>Dear collegues, >> >> >>At which temp and under which conditions >>does mono ammonium phosphate decompose to >>phosphopentoxide (P2O5) ? >> > > >You had better do a DSC and DTG, especially the latter. I would guess >that mono-ammonium phosphate pyrolyzes into a 3-D crosslinked polymeric >mess of phosphorimides. The yield pf P2O5 is probably rather small. > Gee, Uncle Al, I would have predicted simple dissociation at around 300 deg (very approximate guess) to ammonia and phosphoric acid. Then H3PO4 dehydration at higher temperatures to give first the related acids, then P2O5 and its cousins at even higher temps. I would like to learn more about these "phosphorimides." Would they form in a building fire situation? what are their general properties? Jerry DOC0184 Subject: Re: Elevation of boiling point? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/27 Message-ID: <4bsl7f$j80@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <30E238FA.1ADA@imaginet.fr>, Albert CAU says: > >Mohan Kalyanaraman wrote: >> >> dear group, >> Why does water come to a boil on adding tea bag to hot >> water? is it related to elevation of b.p? > >Hi , > >If you observe water boils when you add tea bag, that means the adding of >tea bag produces an exothermic reaction that is enough strong to induce >the boiling of water. > If you want to know more about, you could measure the variation of >temperature after you first boiled the water to prepare tea: this >temperature curve will give you precious indications : the boiling point >of water with tea bag. It seems more likely to me that the boiling is induced by the air bubbles introduced with the tea bag. They act as nucleation sites for steam from the slightly super heated water. Jerry DOC0185 Subject: Re: Elevation of boiling point? From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/28 Message-ID: <4bumeh$q16@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , bram meijboom says: > >mmmmm....... > >Are you sure it's boiling of the water?????? >As far as i'm concerned it simply the air inside escaping. >If a tea bag is trown into the water the paper absorbes water and is >less permeable. So the air inside heats up, increase of presure and if >the presure is high enough air bubles out. >looks like boiling i'd say. > You can bet on the boiling. Throw a tea bag in 80 deg water and what happens? It soaks up water and eventually sinks as air is pushed up and out. Now, as Martin Ystenes says, heat some water to the edge of boiling in a microwave or better yet, heat some recently boiled water. Now try to slip in a tea bag without the water boiling over. Anyone who has worked with boiling chips in a few hundred bumpy distillations can testify to the idea of nucleation. Jerry the microwave DOC0186 Subject: Re: PRAYER, Tue 26 Dec 1995 Overdose sermon From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/29 Message-ID: <4c1ghn$ftn@geraldo.cc.utexas.edu> Newsgroups: sci.bio.misc,alt.sci.physics.plutonium,sci.physics,sci.astro,sci.chem,sci.math,misc.invest.stocks,sci.bio.food-science In article <4bvk49$db2@dartvax.dartmouth.edu>, Archimedes.Plutonium@dartmouth.edu (Archimedes Plutonium) says: > >In article <4bsjmj$7c6@dartvax.dartmouth.edu> >Archimedes.Plutonium@dartmouth.edu (Archimedes Plutonium) writes: > >> Any reader out there ever have a caffeine or chocolate overdose? I >> understand caffeine is an alkyloid with a nitrogen compound and that it >> is like throwing gasoline onto a fire? In overdose, caffeine is a >> dangerous stimulant. Anyway I suspect my science and engineering and >> math will not suffer or abate at all, and perhaps the flow and >> importance will increase. > > I just learned from the Encycl. Brit. that cup of coffee has about >100mg of caffeine and a can of cola about 40mg and a cup of tea about >40mg also. > >No mention of a 100 gram chocolate bar how much caffeine? Are Encyc >Brit. data correct for it seems to me that coca cola has about the same >caffeine per equal volume than does coffee? > >And today I learned that there is another variety of alkyloids called >theophylin in tea which is similar to caffeine but a stronger >upper/stimulant. Does tea have both caffeine and theophylin in >combination? Is a decaf tea meaningless because of the theophylin still >there? Perhaps that is why Britian is addicted to tea time because of >the theophylin which the populace subconsciously craves for the >addiction and which is stronger than even coffee caffeine. > >Does carob have caffeine or one of these alkyloids? Carob makes for a >nice chocolate replacement. > >Is caffeine chemically similar or similar reactions as to nicotine? Archimedes, in addition to caffeine and theophylline there is an isomer of theophylline known as "theobromine" which should interest you. Theobromine is found in rather large quantities (1.5-3%) in the cacao bean. Coffee, tea and chocolate each contain all three alkaloids in different proportions but respectively the predominant species are caffeine, theophylline and theobromine. The physiological effects of the trio are similar in some respects, but quite different from nicotine, which has a more dissimilar structure. The solubilities of the three differ greatly in various solvents, but in general caffeine is more soluble than the other two. Thus, I would not rely on a caffeine extraction process to remove the other two unless they specifically say it does on the label. A mild caffeine overdose can cause jitteriness, cold sweat and nausea. I have experienced the symptoms myself after imbibing too much strong coffee on an empty stomach. I believe I recall reading that carob's claim to fame is that it does not contain caffeine. However, since it tastes so good, there's bound to be something wrong with it :) Jerry DOC0187 Subject: Re: blue sky & ozone From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/29 Message-ID: <4c1sve$qvc@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <1995Dec29.033407.31270@news.bogo.co.uk>, wheatley@mail.bogo.co.uk (Nigel Wheatley) says: > >soma@news.dorsai.org (*selah*) wrote: >> >>Someone told me the sky is blue because of ozone. Is this true? If not, >>could someone explain to me why the sky is blue? >> > >The sky is blue due to the scattering of light by dust particles in the upper >atmosphere. The same phenomenon (Rayleigh scattering) is responsible >for red sunsets. I usually fall down on a good explanation of Rayleigh >scattering (perhaps someone else could add one), but it is NOTHING to do >with ozone! > Both liquid and solid oxygen are pale blue. Does it not follow that the sky is blue because gaeous oxygen is also faintly blue and very abundant? When you're in the midst of an Oklahoma dust storm, the sky turns orange, not a deeper shade of blue. The sky is bluest when the air is cleanest, as after rain storm when the dust has been washed from the air. Jerry DOC0188 Subject: Re: Decomposition of Ammonium Nitrate From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/30 Message-ID: <4c2f6h$92t@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4c226m$ntr@usenet.ucs.indiana.edu>, "John C. Huffman" says: > >mdudley@brbbs.brbbs.com (MARSHALL DUDLEY) wrote: >>If you heat ammonium nitrate it decomposes. I believe that 2 NH4NO3 will >>decompose into 2 N2, 4 H2O and O2. Is this correct? If this is correct, >>then at what temperature does decomposition take place? >> >>Marshall > >At ca. 210C decomposes mostly into H2O and N2O. Remember Texas City? At 210C, yes, but in the texas city explosion it is more likely that the reaction looked something like this: 8NH4NO3 -> 5N2 + 4NO + 2NO2 + 16H2O Not counting the loss of nitrogen oxides to fuel impurities. A trace of organics would have had an enormous effect on the energy release. Both the above equation and the low temperature decomposition to N2O yield only about 130 kcal/kg (approximate) whereas the mixture with 5.7% fuel oil delivers over 1000 kcal/kg. Like gunpowder, AN does not explode to yield its lowest energy products. In the presence of fuel oil though, not only the theoretical maximum energy increases but also the efficiency in producing the optimum low-energy products (H2O, N2 and CO2). Jerry (Ico) DOC0189 Subject: Re: blue sky & ozone From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/31 Message-ID: <4c4uce$k13@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4c3lck$1h6@news.kth.se>, tomas_e@physchem.kth.se (Tomas Eriksson) says: > [Snip, snip, snip] >it's >the individual gas *molecules* in the air; you could say that the colour >of the atmosphere is mainly due to the nitrogen in the atmosphere. Yeah, and you COULD say it is blue because of the oxygen. Either way the bottom line is that air is blue and that's why the sky is blue. If you look at a Dewar of liquid oxygen, it is pale blue. Why is it so difficult to believe that the ocean of oxygen above us is not also "blue." If the blueness were purely the result of diffraction by non-air particles then one might concede that air were not blue. But if the blueness is the result of light being kicked around by air molecules per se, then the first answer to the question "Why is the sky blue?" should be "Because air is blue." The second answer would then be "Air is blue because oxygen (or nitrogen or both) is (are) blue." The third answer could then dive into the area of mechanism, e.g., molecular diffraction. Must we always obfuscate to clarify? DOC0190 Subject: Re: blue sky & ozone From: glhurst@onr.com (Gerald L. Hurst) Date: 1995/12/31 Message-ID: <4c7105$sbt@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4c67qr$enj@news.kth.se>, tomas_e@physchem.kth.se (Tomas Eriksson) says: > [Snip] Sorry, in my last post I used the phrase "molecular diffraction" when I meant "molecular scattering" as opposed to dust scattering. I understand the Rayleigh scattering arguments, but I am still concerned by the question of whether gaseous oxygen is indeed colorless like nitrogen. Both solid and liquid oxygen are blue for whatever reason. Has it been shown that this blueness (of whatever origin) is completely lost when the gas volatilizes? Perhaps you are aware of some spectrophotometric work that has shown this to be the case. In a later article, Lloyd R. Parker says: Dust scatters light, and blue, with the shortest wavelengths, is scattered most. When the dust is high, you see the blue. When the dust is low, the blue is scattered away from you and you see the complement, orange. Can you comment on this dust scattering phenomenon? Jerry DOC0191 Subject: Re: blue sky & ozone From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/01 Message-ID: <4c8400$jho@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Melissa.Hines@Cornell.edu (Melissa A. Hines) says: > >In article <4c7105$sbt@geraldo.cc.utexas.edu>, glhurst@onr.com (Gerald L. >Hurst) wrote: > >> In article <4c67qr$enj@news.kth.se>, tomas_e@physchem.kth.se (Tomas >Eriksson) says: >> > >> [Snip] >> >> Sorry, in my last post I used the phrase "molecular diffraction" >> when I meant "molecular scattering" as opposed to dust scattering. >> >> I understand the Rayleigh scattering arguments, but I am still >> concerned by the question of whether gaseous oxygen is indeed >> colorless like nitrogen. Both solid and liquid oxygen are blue >> for whatever reason. Has it been shown that this blueness (of >> whatever origin) is completely lost when the gas volatilizes? > > >Spectroscopy of O2 gas: > >1st allowed @ 36096 cm-1 = 277 nm <-- UV, no way is this visible > >2nd singlet-triplet (forbidden) @ 13195 cm-1 = 758 nm <-- near IR/deep, deep red > (invisible to most) > >1st singlet-triplet (forbidden) @ 7918 cm-1 = 1.3 um <-- near IR > >The color of the sky has nothing to do with absorption by oxygen. It has >to do with Rayleigh scattering. For a very cogent discussion of this, see >J. D. Jackson, Classical Electrodynamics. pp. 422-425. > >Enough already, > >Melissa Melissa, it may be enough for you. I still wonder if the scattering of very visible blue light does not imply that the unscattered light has a reddish tinge or whatever you get when you subtract some blue. I am not suggesting that oxygen gas necessarily "absorbs" any particular color. There are many solutions you can shine a light through and record different transmitted and scattered or "reflected" colors with a spectrophotometer. If I ran this experiment with a condensed dichroic material I would happily assign two colors to the material - why are the rules different for a gas? What I hear you saying is that if you shine a beam of white light through air and put spectrophotometers at 180 deg and 90 deg, both of these instruments are going to record "color," not because of absorption, perhaps, but color nevertheless. Liquid oxygen is blue, period. I don't know if it is blue because it scatters blue light or because it absorbs some other frequency, but it is positively blue. If this blueness disappears on volatilization, then I for one want to know what caused the color in the first place and why it disappeared in the gas phase. On the other hand, if the blueness of oxygen continues into the gas phase then I want to know why we would tend to deny that the gas is blue, citing rayleigh scattering as though that mechanism somehow made the blue color no longer count as such. And finally, I would like to know if the color of the sky would be exactly the same if we had essentially the same total amount of atmosphere but with nitrogen replacing all the oxygen. Jerry (Ico) DOC0192 Subject: Re: Nitroglycerine (medicine), storage & handling From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/04 Message-ID: <4cfef0$cpc@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <30eafa3b.0@news.cybernet.dk>, kurir@cybernet.dk (Nancy Andersen) says: > >Do anyone have experince with handling and storage of nitroglycerine >for medical use? > >Nitroglycerine for medical use is dissolved in ethanol, and is >harmless until spill occur and ethanol evaporates (my idea!). Does >anybody have any experince, and if so what to do if spill occurs. > If the spill is on a non-porous surface, use a large excess of sawdust to soak up the liquid and later burn the mixture in the open in a thin layer and remotely. If the spill is on a porous surface, repeated treatment with an 18% sodium sulfide (Na2S:9H2O) will destroy the NG. Jerry (Ico) DOC0193 Subject: Re: PRAYER, Sun 31 Dec 1995 Carbon in us, Carbon of Plutonium, From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/04 Message-ID: <4ch7ur$fhd@geraldo.cc.utexas.edu> Newsgroups: sci.bio.misc,alt.sci.physics.plutonium,sci.physics,sci.astro,sci.chem,sci.math In article <30EC145E.3034@algemeen.mt.wau.nl>, Marc Boncz says: > >After taking a glance at AP's personal homepage >(it is on http:_//mmm.dartmouth.edu/pages/user/plutonium/) >evrybody will be comvinced of the state of mind of this guy. >He got no idea of what seriuos readers think of his spamming: > >>My newsgroup on the Internet is named "The Altar of Science & Physics is >>Plutonium " and aptly abbreviated >>"alt.sci.physics.plutonium" can be telecommed here >>alt.sci.physics.plutonium. Warning: my web site is under continual >>revision and often I use my newsgroup and the minor ones such as sci >>hierarchies as forums of discussion, hotly debated, >>for my new ideas. > >I think he uses these groups more for his hobby: >>Some of my hobbies are bicycling and -->writing science fiction stories.<-- > >What wonders me is what he is doing at this college. He is listed as >'College Staff' in this University's WWW-pages, but he seems to occupy >his time with making money on the stockmarkets. Wat is Dartmouth paying >him for? BTW: He also uses the name Ludwig.Plutonium@dartmouth.edu., or >at least he used it. An idea for mail&reply? > "Serious readers" vary in their attitude toward Archimedes. Some believe he adds a certain dash of color to otherwise sometimes rather stuffy forums. Wonder no more. Archimedes is one of those very rare University employees who actually earn their pay by hard work. He previously used the name "Ludwig Plutonium" because it was his legal name; now it is legally "Archimedes Plutonium," which really has a better ring. Jerry (Ico) DOC0194 Subject: Re: Vapour Pressure - Mixtures From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/04 Message-ID: <4ch8u4$fhd@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4ch1kj$69s@grid.direct.ca>, tmiller@diachem.com (Tom Miller) says: > >It's been a long time since phys chem... how do I calculate >theoretical vapour pressure of a mixture including a nonvolatile, >nondissociable solute... eg the following recipe: > >water 70% by mass >ethanol 20% by mass >sugar 10% by mass > Ideally, convert your mass fractions to mole fractions. The partial vapor pressure of each volatile component is the product of the respective mole fraction and the vapor pressure of the pure compound. Unfortunately, the water/ethanol system is nowhere near ideal, so your calculations will be nowhere near correct. There are tables and graphs for the water/alcohol system which show a low boiling azeotrope at about 94% alcohol. Jerry (Ico) DOC0195 Subject: Re: 'Lavalamp'- which fluids are used ? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/06 Message-ID: <4cl5vc$1n1@geraldo.cc.utexas.edu> Newsgroups: can.schoolnet.chem.sr,fj.sci.chem,iijnet.chem,no.kjemi,sci.chem In article , tice@nai.net (Bradley D. Tice) says: > >I don't think it's water in there. I believe it's a liquid that changes >density through electrical stimulation. It could also be temp, but I don't >think so. I heard an interview with the inventor, he's not saying, and >he's patented it and doesn't license it. > Bradley, maybe you better stick to physics. OK, I'll bite, how do you electrically stimulate a liquid? With a cattle prod? :-) Jerry DOC0196 Subject: Re: New definition or concept: Half-life of One single Atom From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/06 Message-ID: <4cn1nf$7p3@geraldo.cc.utexas.edu> Newsgroups: alt.sci.physics.plutonium,sci.physics,sci.chem,sci.physics.particle In article <4cn01j$9ia@ixnews8.ix.netcom.com>, quantum4@ix.netcom.com(Thomas Robertson ) says: >> >>>The probabilities of decay of a given atom are: >> >>0.5 0.75 0.125 0.0625 0.0313 0.0156 0.0078 >> 1 2 3 4 5 6 7 > >I presume there is a typo in the second calculation where you should >have put 0.25 instead of 0.75. > It should be "probability of survival" with the second figure as 0.25, else we need also to subtract each of the figures from 1.0000 to get "probability of decay." Jerry DOC0197 Subject: Re: New definition or concept: Half-life of One single Atom From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/06 Message-ID: <4cmppe$qi1@geraldo.cc.utexas.edu> Newsgroups: alt.sci.physics.plutonium,sci.physics,sci.chem,sci.physics.particle In article <4cmg44$kc7@news.acns.nwu.edu>, "Todd K. Pedlar" says: > >Not really - the figures which you have quoted are first of all the >probabilities at N half-lives that the atom has not yet decayed. >Secondly, all you've done is shown an approximation to the MAXIMUM life >of an atom, not really its "full life." Technically, the maximum lifetime >for a given atom would be infinite. What is the meaning of "full life", >anyway? If you were to choose a single atom to observe until it decays, you >might find that it "lives" 30 seconds or 30 billion years. Is its full >life 30 seconds or 30 billion years? In my opinion, the most meaningful >statistic for a single atom is probably the "mean life", which is simply >the average lifetime of a given atom. This is equal to the half-life >divided by log(2), or 0.693. There is a simple derivation of this, which >can be found in any nuclear physics text, such as Introductory Nuclear >Physics by K. Krane. > Not really. The figure you quote for the "mean life" is actually the "mean future life." Any real sample of U238 atoms with a mean future lifetime of of 0.693 half-lives already has an age of many half-lives. You might say the majority of the existing atoms have a long history and a short future :) Jerry DOC0198 Subject: Re: Fresh water from sea water - new economical process From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/07 Message-ID: <4cplad$q44@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.engr,sci.engr.chem,sci.chem,sci.misc,sci.research In article <4cpelm$t8n@ixnews8.ix.netcom.com>, ferrad@ix.netcom.com(Adrian Ferramosca ) says: > >There are a few sceptics out there, notably glhurst and oakes. > >I did not say that I have been theorizing about this process. This >phenomenon does actually happen. I have done experiments and have >obtained yield and purity figures. What I have done in the patent is >merely tried to create a commercial process to exploit this behaviour, >which could potentially be much cheaper the reverse osmosis. I have my >own ideas to explain the mechanisms, but ... read my lips ... it DOES >happen, try it sometime. > We sceptics don't doubt that you can separate salt from water by freezing. But the handwaving, smoke and mirrors about the water vapor in the escaping CO2 carrying away enough heat to freeze the solution from which it came does not compute thermodynamically. Furthermore, you tell a completely different story in the patent abstract, which says: *A solute can be separated from a solute/solvent solution by dissolving a gas-forming material into said solution and then adjusting the temperature, pressure and solute concentration of the resulting solution such that a Joule-Thompson free expansion of the gas-forming material released from the solution will produce a three-phase separation of the components of said solution.* The US Patent Office does not require a correct theory to issue a patent. But when you tell them that a processt works by the Joule-Thompson effect of CO2 and then tell sci.chem it works by a water vapor mechanism, you're gonna have credibility trouble with the chemists. Jerry DOC0199 Subject: Re: Magnesium From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/07 Message-ID: <4cpb0v$iak@geraldo.cc.utexas.edu> Newsgroups: rec.pyrotechnics,sci.chem In article , oleum@spuddy.mew.co.uk (Nick Hiams) says: > >>>Um, you are ignoring the 64 kcals/mole that it requires to break the H2O >> >>It's mol, not mole. > >If you're that picky, then it's preferably 270 kJ mol-1. > >(At least in the *real* scientific/metric world that most of us live in:*) > >--TheAlchemist Not really. You label yourself as an amateur with a comment like that. The "real world" is chock full of tables of data in calories. Most experienced chemists learned their trade long before it became fashionable to use Joules to accomodate the physicists and ease the pain of conversion to mechanical units. After the SI conference in 1960 there was a general feeling that all other units were dead because the delegates from 36 countries had met and more or less so decided. The momentum was so strong that by 1973, when Lange's 11th edition came out, the conversion tables only gave factors for translating to SI units. Now take a look at the 13th edition. The complete tables are back so that one can readily convert form calories to ergs or BTUs. This apparent backsliding was undoubtedly the result of gripes by "real world" chemists who were not about to toss all their reference works into the trash bin. International committees meet all the time to decide everything including the fate of nations, but the world has a way of going on about its business as usual. Don't misunderstand me. The Joule is a perfectly fine measure of energy. But many of us who speak SI fluently prefer to communicate in our native dialect. And for those of you who don't understand the language there's always Lange's 11th edition. Let a few more generations of chemists pass and about the time the average US citizen begins to think metric, the SI system will be the colloquial form. Then some committee somewhere will be working to replace it with something more modern. Jerry (Ico) Jerry DOC0200 Subject: Re: Fresh water from sea water - new economical process From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/08 Message-ID: <4cpnh0$s2f@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.engr,sci.engr.chem,sci.chem,sci.misc,sci.research In article <4cpimp$447@ixnews8.ix.netcom.com>, prakash2@ix.netcom.com(Prakash R. Shah ) says: > > >Didn't some explorer find that out a long time ago? He found that the >glaciers and stuff were freshwater even though the seawater was salty. >I'm not sure about this, though. But if we do use this method, we'll >be using up seawater just like we use up freshwater today, although >there is a lot of seawater. Don't worry about the lost seawater. Someone will undoubtedly open a seawater recycling plant before the ocean levels drop more than a few feet. Jerry DOC0201 Subject: Re: Fresh water from sea water - new economical process From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/08 Message-ID: <4cqcs9$bbo@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.engr,sci.engr.chem,sci.chem,sci.misc,sci.research In article <4cq1aa$93a@cloner3.netcom.com>, ferrad@ix.netcom.com(Adrian Ferramosca ) says: > >I agree, if you're talking steady state. But it does occur, and the only >explanation I can put forward is that the kinetics of the process dictate that >the energy of the system gets temporarily shifted towards the departing gas >phase. Eventually, if left to reach steady state, it will distribute evenly, >and return to the 'can' and cause the ice to melt. > You're not going to beat thermodynamics with a kinetic stick. If "the the energy of the system gets temporarily shifted towards the departing gas phase," then you have harnessed Maxwell's demon and perpetual motion is just around the corner. All you have to do is let that energy segregated in the escaping gas flow through a heat engine on it's way back to the can. What you are suggesting is that you suspend the second law for a little while, but its OK because you pay back the temporary loan of free energy later. That's a neat trick: borrow heat then pay it back through an engine, then borrow again and so on ad infinitum. >>Furthermore, you tell a completely different story in the patent >>abstract, which says: >> >> *A solute can be separated from a solute/solvent solution by >> dissolving a gas-forming material into said solution and then >> adjusting the temperature, pressure and solute concentration >> of the resulting solution such that a Joule-Thompson free >> expansion of the gas-forming material released from the >> solution will produce a three-phase separation of the >> components of said solution.* > >This is patent attorney speak - he was hit on this Joule-Thompson >thing. I am a chemical engineer, what I stated as: >1. dissolve CO2 into seawater at an elevated pressure >2. cool it to just above freezing >3. instantaneously drop the pressure to atmospheric >4. ice forms >5. remove ice >6. melt ice >7. drink water > >was translated to the above. > You're telling us that you let a patent lawyer stick a bogus theory into your patent. What earthly reason would he have for doing that? Patents do not require a scientific theory of why they work, and the existence of a credible theory actually weakens the claims of novelty in terms of an invention not being obvious to one of ordinary skill in the art. A patent attorney would prefer an invention which works by a mechanism nobody can explain. A smart lawyer would hardly volunteer a worthless theory. >>The US Patent Office does not require a correct theory to issue >>a patent. But when you tell them that a processt works by the >>Joule-Thompson effect of CO2 and then tell sci.chem it works by a >>water vapor mechanism, you're gonna have credibility trouble >>with the chemists. > >I won't get into the chemist / chemical engineer debate, but I thought >they might be interested. This is an item of primarily chemical >engineering interest, so I don't expect much response from that side. > Whoa!! This is not a debate between chemical engineers and chemists. The tools of the two trades may be different, but both rely on the same fundamental science. If it doesn't work thermodynamically for a chemist, it won't work for an engineer either. Jerry (Ico) DOC0202 Subject: Re: Ozone layer/Dobson Units From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/08 Message-ID: <4cs2of$bgr@geraldo.cc.utexas.edu> Newsgroups: sci.physics,sci.environment,sci.geo.meteorology,sci.chem In article , ahansen@sisnet.ssku.k12.ca.us (Amy Hansen) says: > >Hello my name is Amy and I am a physics student attending Mt. Shasta High >School. In my physics class the students are required to find data over >the internet and to form a question, hypothesis, research it etc... > >I found some really interesting data on the Ozone content at different >stations accross the world. If interested in viewing the web sight the >address is; http:// www.cmsl.noaa.gov/dobson_homek/dobson.HTMl > >Anyway the data is measured by using a dobson unit. I have tried to >research what a dobson unit is but haven't been able to find anything. >Does anyone know? > >I was also wanting to know more information about the ozone and how it is >affected by the seasons. If anyone can help me I would greatly appreciate >it. > Amy, Dobson units are derived by measuring the intensities of two wavelengths in the absorption band of ozone. The ratio of these two intensities as measured by a spectrophotometer provides a basis for the calculation of the ozone content of the atmosphere. Jerry (Ico) DOC0203 Subject: Re: Fresh water from sea water - new economical process From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/09 Message-ID: <4cuknp$84r@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.engr,sci.engr.chem,sci.chem,sci.misc,sci.research In article <4cuhnt$571@dawn.mmm.com>, cewright@mmm.com (Carl Wright cc0197) says: > >Adrian Ferramosca (ferrad@ix.netcom.com) wrote: >: There are a few sceptics out there, notably glhurst and oakes. >: >: I did not say that I have been theorizing about this process. This >: phenomenon does actually happen. I have done experiments and have >: obtained yield and purity figures. What I have done in the patent is >: merely tried to create a commercial process to exploit this behaviour, >: which could potentially be much cheaper the reverse osmosis. I have my >: own ideas to explain the mechanisms, but ... read my lips ... it DOES >: happen, try it sometime. > >You have just discovered for yourself the process of crystallization, >whereby materials may be purified. My daughter (6th grade) is doing >this for her science fair project. Try the same thing with some water >having red dye added to it instead of being carbonated. That's the >trouble with many great ideas, they've been done before. > You underestimate the breadth of the claims being made for this invention. The inventor says he is not merely purifying salt water by freezing but that he is achieving the freezing of large amounts of water by flashing off relatively small amounts of CO2. In other words he claims a spontaneous process which goes up the free energy hill, at least temporarily, because of the kinetics of the process. The novelty of the claims may be judged by the fact that standard enthalpy change for his process can at best account for the freezing of about 2 percent of the mass of the salt water. Jerry DOC0204 Subject: Re: Red Mercury From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/09 Message-ID: <4cujib$84r@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , thallion@synchron.ct.se (Thallion) says: > > > YS> It appears that there is colorable evidence > YS> that "Red Mercury" is an actual substance, > YS> and a strategic one at that. > > Sw> I have seen this so called 2020 (refering to its density) on a TV > Sw> recording. According to the formula it is a free radical. Who ever > Sw> invented this (meta?) stable substance should apply for the Nobel > Sw> Price in both physics and chemistry! I don't belive such a substance > Sw> excist. > >According to a documentary I saw once, the data on the compound was the >following; they didn't show it explicitly, but it was readable on some >papers on some professor's desk if the VCR was paused. > > Melting Point: -37.87?C >Molecular Weight: 756.61 u > Density: 20.20 Kg/dm3 > MC (?): 196.0127 ? 2% > Formula: Hg2Sb2O7 > >Can someone synthesize this compound, and see if it is red? :) > Salts of the general type M2As2O7 are known where M is a divalent metal. There seems to be no reason why the mercuric salt should not exist, but one would hardly expect it to have a low melting point or a density anywhere near 20. Whatever MC is, they certainly seem to know how to measure it accurately. Jerry (Ico) DOC0205 Subject: Re: Fresh water from sea water - new economical process From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/10 Message-ID: <4cvqfr$4lq@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.engr,sci.engr.chem,sci.chem,sci.misc,sci.research Article Segment 1 of 2 In article <4csu4a$aa@ixnews8.ix.netcom.com>, ferrad@ix.netcom.com(Adrian Ferramosca ) says: > >He won't give up, will he ... > >In <4cqcs9$bbo@geraldo.cc.utexas.edu> glhurst@onr.com (Gerald L. Hurst) writes: >> >>In article <4cq1aa$93a@cloner3.netcom.com>, ferrad@ix.netcom.com(Adrian >Ferramosca ) says: >>> >>>I agree, if you're talking steady state. But it does occur, and the only >>>explanation I can put forward is that the kinetics of the process dictate that >>>the energy of the system gets temporarily shifted towards the departing gas >>>phase. Eventually, if left to reach steady state, it will distribute evenly, >>>and return to the 'can' and cause the ice to melt. >>> >>You're not going to beat thermodynamics with a kinetic stick. If >>"the the energy of the system gets temporarily shifted towards the >>departing gas phase," then you have harnessed Maxwell's demon and >>perpetual motion is just around the corner. All you have to do is >>let that energy segregated in the escaping gas flow through a heat >>engine on it's way back to the can. > >No, I'm not saying that you get it all for free, but unsteady state effects can >shift equilibrium. Nothing ever occurs at steady state. If you can harness the >articial separation of energy, you can get in this case the required product, >and do whatever you want with the higher energy stream. You will obviously not >get back anywhere near the energy put in, but the idea here is to keep the low >enthalpy product, we don't need the high enthalpy one! Let the product warm >itself up of its own accord. > Sorry you think I'm being stubborn. It's just that I seem to have persistent doubts about spontaneous processes which result in a net decrease in entropy, even if they occur only for a few minutes. Let's look at your process in its simplest form. You have a can of carbonated salt water similar to a salty diet Coke. You chill it down to its freezing point at say -2 degC. Let's assume we're dealing with one liter of solution with a rather high (compared to Coke) equilibrium CO2 pressure of 4 atmospheres. Let's further make the (incorrect) assumption that when we pop the lid, the CO2 is going to bubble off instantly leaving us with a residual CO2 pressure of one atmosphere. The solubility of CO2 in a liter of water is about is about 1.85 liters/atmosphere and a one-molar slt concentration will vave little effect on this value. If the CO2 pressure drops from 4 atm to 1 atm absolute, the Amount of CO2 released at about -2 deg will be about 1,85liter/atm*3atm*1mole/22.2liter = 0.25 moles CO2 The enthalpy change for CO2(Aq) -->CO2(g) is about -4.85 Kcal/mole hence the volatilizing CO2 should absorb about 4.85Kcal/mole*0.25mole = 1.25 kcal. Water requires the loss of about 0.080 Kcal/g to freeze, hence the amount of ice created by the escaping CO2 should be about 1.25Kcal/0.080Kcal/g = 15.6 g or about 1.6% of the original water. Now let's look at the contribution of water vapor in removing heat from the solution. The vapor pressure of water at -2 degC is about 4mm. If the vapor entrained by the escaping CO2 reaches saturation then the 0.25 moles of the former should carry with it approximately 4/760*0.25 = 1.3exp-3 moles of water vapor. Multiplying this value by the ratio of the heat of fusion to the heat of vaporization yields 1.3exp-3moles*540cal/g/80cal/g = 8.8exp-3 moles of ice or about 0.16grams, an insignificant amount even compared with the merely small (15.6 grams) amount produced by the CO2. At this stage we see that the expected thermodynamic changes can only account for enough energy transport to freeze about 1.6 percent of the water. Clearly an economical process will require freezing at least the bulk of the fluid, let us say certainly no less than 50 percent or in the current example no less about 500 grams. DOC0206 Subject: Re: Fresh water from sea water - new economical process From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/10 Message-ID: <4cvqfr$4lq@geraldo.cc.utexas.edu> Article Segment 2 of 2 If the carbon dioxide and water vapor could leave the solution at a higher temperature than the liquid we could theorize that by some quirk of kinetics the warm gas could carry away the necessary amount of heat. This is only a pipe dream though because in order for it to happen the net sum of q/T for the liquid and gas phases would have to be negative, that is the entropy of the liquid would go down more than the entropy of the gas went up. Unless we are to break the second law, it is a no go. The alternative, which has been suggested by the inventor, is to have more energy removed by water vapor (since we have much more water than CO2). If the water is to carry off more heat, it has to be vaporized to a partial pressure greater than its equilibrium vapor pressure of 4mm and maintained at -2 deg (or slightly lower as the solution becomes more concentrated) at least until it is no longer in thermal contact with the liquid. In other words we have to produce a mix of CO2 and water vapor at -2 deg or less which is in a metastable supercooled state with respect to the water vapor. The amount of water vapor in the CO2 required to carry away the latent heat of fusion of the freezing water is readily calculated by multiplying the 500 g of ice desired by the ratio of the heat of fusion to the heat of vaporization 500g*80cal/g/540cal/g = 74 g of water vapor or 74g/18g/mole = 4.1 moles. Our product gas the consists of 4.1 moles of water vapor mixed with only 0.25 moles of CO2, all at -2 degC. Ignoring the relatively minor CO2 content, we have an astounding 91 liters of ice cold super-cooled steam - the same as if we had been able to cool 125 liters of regular steam through 102-103 degC without it condensing. Imagine now that as expected this cold steam is unstable and reverts to its natural state of water and hot steam. As the cold steam condenses it forms water which is heated at the rate of 18 cal/deg/mole by the vapor which is surrendering about 9.72 kcal/mole. The process goes on until [(4.1-N)*8.2cal/deg+N*1cal/deg]*102deg=9720*Ncal, that is until the amount of heat provided by N condensing moles out of 4.1 provides enough heat to warm up both the condensed (N) and uncondensed (4.1-N ) moles of water to 100degC. The only new data here are the heat capacities of liquid water (18cal/deg/mole) and water vapor (Cp = 8.2 cal/deg/mole) If I did the math right, N (the amount of water condensing) is only 0.33 moles so the final equilibrium mixture consists of O.33 moles (6 grams) of boiling hot water and 4.1-0.33 = 3.8 moles (68 grams, 116 liters) of live steam. These calculations are only approximate, but they lead me to believe that if the proposed desalination process works as described, the next cold Coke you open may blister your face with a blast of steam. If you find any mistakes in the math, be advised that I was just testing you. Jerry (Ico) DOC0207 Subject: Re: Fresh water from sea From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/11 Message-ID: <4d1ogo$f7c@geraldo.cc.utexas.edu> Newsgroups: sci.chem Article Segment 1 of 2 In article <8B892C5.00EE001827.uuout@digitec.co.za>, brian.tinniswood@digitec.co.za (BRIAN TINNISWOOD) says: > >Hello Alan, > >On 06 Jan. 96 17:24 Alan \"Uncle Al\" Schwart wrote to All... > > AS> Has somebody worked out the thermodynamics and the material unit > AS> processes? I'm talking rigorous differential equations, not > AS> back-of-the-envelope approximations. > >Don't make me laugh! Too many good ideas have been lost by getting >ourselves drowned in a sea of higher mathematics. Why don't we do lab >scale testwork, then bench scale then finally pilot work before we make >any judgements? > >Remember, science is a set of *arbitary* rules that only approximate >nature. Remember also, that the models we devolope are very often >constrained by tight assumptions or parameters, and very often >these models have been proved to be inaccurate or downright wrong. > >Lets do the test work, then the mathematics and *then* we will be >in a better position to make a sound judgement of any new idea. > I don't think so. We have developed mathematical and conceptual models precisely in order to give us the ability to predict the outcome of experiments we have not run. Obviously, our models are always inexact to some degree and in some cases downright wrong. The art in science is to be able to judge well the reliability of our theories. When a law has been tested and retested like the second law of thermodynamics, the burden of proof falls on whoever proclaims they have found a loophole. Most often these would-be lawbreakers assert that they are merely skirting the law, not defying it. Shall we run into the laboratory to test every claim of every inventor of every patent? There are more than 5 million of these documents extant. There are not enough laboratories in the world to test every outrageous claim to new technical breakthroughs. Take the example of cold fusion. Millions of dollars worth of resources have been poured into answering the simple question about whether the phenomenon exists at all. Yet after years of research by various people world wide, there are still two entrenched warring camps arguing about simple energy balances. Are they getting more energy out than they put in? Here we are dealing not with esoteric nuclear energy theories but with a classical physico-chemical process. If the inventor can explain how his invention works within the framework of accepted simple thermodynamic and kinetic theory that is fine. However, if he is saying that he has discovered a PVT process which cannot be readily explained in terms of accepted theory, then it is up to him to show why others should expend the time and effort to confirm his results. So far all we have heard is that "something else" is happening to remove the heat. Whatever we might assume is occuring short of the simple disappearaneof that energy from the universe should be manifesting itself in measurable and measurably hot products of which we have neard nothing If the sudden release of a little carbon dioxide from cold water can freeze 25 or 50 times as much water as is predicted by the accepted value of the heat of solution then the importance of the phenomenon far exceeds that of a new desalination process. The very fact that the inventor sees only his immediate invention suggests to me a lack of appreciation of more revolutionary aspects of the supposed process. Before we rush into the lab or pilot plant, let's ask the proponents of the new process to give us some accurate experimental data on mass flow, composition and temperatures. If their data support their novel conclusions, more power to them and may they win a Nobel prize. Believable and detailed data, if supportive of the theory, will send experimenters galore into the laboratory to chase the elusive Eldorado of free (or at least cheap) energy transfer. DOC0208 Subject: Re: Fresh water from sea From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/11 Message-ID: <4d1ogo$f7c@geraldo.cc.utexas.edu> Article Segment 2 of 2 Personally, I think their thermometer is off a few degrees and they are unknowingly super-cooling the Coca-Cola. In my own limited experience of several decades drinking soda pop, I have observed that as the liquid approaches 0 degC the pressure of the CO2 drops to the point where one gets only the gentlest of little "pops" when the cap is removed. It is when the soda gets either super-cooled or actually well frozen that the eruptions occur and in the former case give the illusion that the escaping gas freezes the liquid rather than merely initiating the process. Jerry (Ico) DOC0209 Subject: Re: Fresh water from sea water - new economical process From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/11 Message-ID: <4d3tcl$qpo@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.engr,sci.engr.chem,sci.chem,sci.misc,sci.research In article <4d27no$c49@ixnews8.ix.netcom.com>, ferrad@ix.netcom.com(Adrian Ferramosca ) says: > >Freezing is the changing of state from liquid to solid of a homogeneous >compound due to a reduction in temperature. Crystallization, on the >other hand, is the combining of aqueous ions into a solid, due to >removal of solute. The only connection is the solid, the process is >very far removed. In the former, the same molecules transform from >liquid phase to solid, in the latter, a combination of aqueous ions >forms a new component which can crystallize out. > Is this your personal definition of "crystallization"? There are a few of us who interpret the word as simply describing any transition to the crystalline state. Among us few are the various dictionaries of the English language. Jerry DOC0210 Subject: Re: Fresh water from sea water - new economical process From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/11 Message-ID: <4d2lgo$1kf@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.engr,sci.engr.chem,sci.chem,sci.misc,sci.research In article <4d2i8f$d5f@dawn.mmm.com>, cewright@mmm.com (Carl Wright cc0197) says: > The coke >example that you used is the one that got me started also. In the >coke example, the material in the bottle doesn't freeze because it >contains dissolved material (CO2) which lowers the freezing point >of the mixture below zero degrees Centigrade. When the bottle is >opened, the CO2 escapes and the freezing point of the resulting >solution is exceeded. I snipped most of your article because I agree with it. I just wanted to point out that the CO2 does not act as much of a freezing point depressant because it is present at a molal concentration well under 0.25. The fraction of a degree F.P. average change from partial volatilization could, however, act as a nucleation starter, particularly if augmented augmented by strong localized cooling at bubble interfaces. That is assuming that the coke is super-cooled before the lid is popped. You are certainly correct in equating the process to conventional purification by crystallization. Jerry DOC0211 Subject: Re: What is the difference between KEROSINE oil and ODORLESS MINERAL OIL From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/11 Message-ID: <4d2mt1$1kf@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4d2m4v$p1b@news.asiaonline.net>, susana@asiaonline.net (susana chan) says: > >On 7 Jan 1996 23:31:16 GMT, you wrote: > > >>I have a lamp that came with oil that is odorless. The lamp is a fine piece >>of glass art. it is like a klein bottle, and totally transparent. The inlet >>for oils is open, and there is no mechanical part, not even a screw. After >>several years, the oil has not evaporated. The oil is odorless. Now I know >>that traditionally such lamps use kerosine oil. I wonder where to get this >>odorless oil. What is it? Some people say that it is deodorised kerosine >>oil. I wonder what is difference between a deodorised kerosine oil and >>non-deodorised one. How to deodorise kerosine oil? > >>Please contact via email. >>Thanks a lot! > >>lbliao > > >I have the same problem as you. I have put the same question in the >newgroup just at the end of 1995 but I can't get any answer. If you >get any method to deodorise the kerosine, please teach me. >On the other hand I found fuming sulphuric acid may be used to wash >the kerosine but I have not tried. It is harmful to breathe that acid. >Take care. Let me tell you what little I know. Sulfur compounds seem to be the culprits in hydrocarbons. They are removed along with nitrogen compounds by passing the petroleum vapors over catalysts at high temperatures. My guess is that odorless kerosene and mineral oil are probably also treated with activated carbon. You can get at least most of the way there by buying 1-k kerosene aka k-1, which is specified by kerosene heater manufacturers. Anyway, truly odorless kerosene or its near equivalent odorless #2 diesel fuel oil are available commercially at a reasonable price. The materials are used, inter alia, to make ANFO for blasting minerals intended as additives for cattle food. It seems the cattle or at least their milk consumers do not like the taste of kerosene. Jerry (Ico) DOC0212 Subject: Re: 12 Yr Old Son Science Exp. - Need Help! From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/13 Message-ID: <4d95di$74d@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4d8rlt$r20@ixnews6.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: > > 2) Capillary water, as trapped between two microscope slides pressed >together under water or in the minute interstices of a finely porous >solid, can equilibrium melt as low as -40 degrees celsius. The surface >properties of water are very much different from its bulk properties >(e.g., surface tension). Trapped in very thin layers, a few micrometers >thick or less, there is >no< bulk water. Capillary water has very >different physical properties. > This freezing point depression in capillaries is extremely interesting and new to me. Could you please elaborate on the subject? I wonder if such a phenomenon might have misled the would-be discoverers of polywater. I would have assumed that any effect on the FP would be just the opposite because of the tension on the water and the potential molecular aligning effects of a polar surface. That's twice I've been wrong in the last 2 minutes :) Jerry (Ico) < DOC0213 Subject: Re: Endothermic Reactions From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/13 Message-ID: <4d7otf$aqg@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4d7met$c7e@cloner2.ix.netcom.com>, aryal@ix.netcom.com(PAM HOFFMAN ) says: > >I haven't had much luck in my search for endothermic reactions. I would >like to find a relatively simple reaction which would freeze water at >ambient temperatures. I believe there is one which involves using a Ba >salt compound, but as yet it remains a mystery. Any assistants would >be greatly appreciated. > Why not simply the "reaction" of salt with ice to form salt water. It is so endothermic that it is widely used to make ice cream. Im sure you have been told you can also use the dissolution of ammonium nitrate in water to freeze water on the outside of the beaker. Jerry DOC0214 Subject: Re: Fresh water from sea water - new economical process From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/13 Message-ID: <4d96m8$cp8@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.engr,sci.engr.chem,sci.chem,sci.misc,sci.research In article <4d916s$cjk@mozo.cc.purdue.edu>, bianchi@widget.ecn.purdue.edu (Marcus V Bianchi) says: > >I don't see much of a problem in this discussion, other than the fact that >crystallization happens during the freezing of a salt solution. > >Anyway, I believe there has been a point missing here: the phase diagram of >a water-salt mixture. It is pretty simple to show in such a diagram the >reason for the purity of the crystal phase, if the salt concentration is >small (which is the case for sea water). The crystal formed in such >situation has pure water on it and the solute segregates in front of the >solid-liquid interface. It is the purification process that we have been >discussing here. > >Does this help? > What you say is true, but it has not much to do with the heart of the ongoing discussion. The question is whether CO2 rapidly escaping from seawater can freeze substantially more water than can be accounted for by the accepted heat of solution of the escaping CO2 and the heat of vaporization of the calculated equilibrium water vapor entrained therein. One side of the argument holds that the standard thermodynamic values for heat extraction are much lower than the actual results because of some unspecified or unknown kinetic effect. The other side opines that the kinetics cannot result in more heat separation between the phases without violating the laws of thermodynamics. Take a seat and take a side, if it please you. The discussion of "crystallization vs freezing" was a side issue, it being universally agreed that freezing water segregates dissolved salts. Jerry (Ico) DOC0215 Subject: Re: What is the difference between KEROSINE oil and ODORLESS MINERAL OIL From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/13 Message-ID: <4d7o5l$aqg@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4d7hqu$51r@scoville.wsrcc.com>, alison@wsrcc.com (Alison Chaiken) says: > >What exactly is mineral oil, anyway? Dictionary says, "a light >petroleum distillate." Does that mean that it's whatever combination >of distillates are readily available and cheap at the time of >bottling? It seems surprising that mineral oil is non-toxic if it's >petroleum-based. > In the broadest sense mineral oils are simply hydrocarbon oils derived from petroleum as opposed to vegetable (or animal) oils which are basically triglycerides. Petroleum products often contain poisonous components including an array of aromatic materials and sulfur and nitrogen compounds. The "mineral oil" we see in the drug store is what the british call "petrolatum oil," a highly purified, mostly aliphatic hydrocarbon oil which is usually clear as water and virtually tasteless and odorless. A cousin to this material is petroleum jelly or petrolatum, which is made mostly of aliphtic hydrocarbons of higher molecular weight. Jerry (Ico) DOC0216 Subject: Re: oklahoma explosive From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/13 Message-ID: <4d94l9$74d@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4d8mp1$r20@ixnews6.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: > >The nature, and hence geometry, of the OK City explosion is open to >question. > >Ammonium nitrate/fuel oil emits a vast red-brown plume of NOx when it >pops. I did was involved in oil shale work in 1970 for Occidental >Petroleum, in Colorado. It took three days to ventillate the galleries >after a blast. > >The OK City explosion was heard 40 miles away. Official truth claims up >to five tons of ANFO in the device. How is it nobody witnessed/recorded >a 400 foot NOx geyser? Where are the residues from the blast? Analysis >of hydrocarbon deposits could fingerprint the source of the diesel (or >whatever). The amount of visible or at least noticeable NO2 varies greatly with the exact oxygen balance. One sees the clearest orange-brown vapor from the venting of underground shots in wet conditions. Surface shots always produce a great cloud of dust into which NO2 can blend to simply look like more dust, especially in Oklahoma, where dust storms look like NO2 gas attacks. Many times, NO2 is not even visible from clean surface shots. > >Two seismic waves were recorded. Had the device been a fuel/air bomb, a >"small" charge would rupture the vessels and nebulize/disperse the fuel >cloud. Detonators would then trigger the vapor/mist cloud in air, and >KABOOM! As air is the oxidizer, the device would scale down to about >500-700 lbs tops with no residues and no plumes. Of course, such a >device would require non-trivial design and computer modeling (commonly >only available to a government). > The number of events recorded by seismometers is a highly debated topic among the cognoscenti. There is no really persuasive evidence for more than one blast, (at least that I have seen). I've also listened to the two tape recordings of the event from near and far. Some say they hear two events; I hear only one. >Had it indeed been a fuel/air munition, the inverse square law would NOT >obtain! The very large projected area of the cloud before detonation >would not be a point source, it would approximate a plane wave detonation >- NO initial decrease in power with distance, then a much slower decrease >than inverse square. Even a line source only decreases linearly with >distance. If the explosive had been a fuel-air mix, there would have been no crater. There is no basis at this time for suspecting that FAX was involved. >One last thought. How is it that all "targeted" government personnel >were evacuated shortly before the blast, leaving children, innocents, and >a Dept. of Agriculture office to be slaughtered? > Just who were these "targeted" personnel and how do we know they were targeted? Who targeted them? Neither McVeigh nor any hypothetical "insiders" have have yet testified on this subject. Uncle Al, it is a big grin to learn that you are a conspiracy buff. If you find any real evidence for any of the above disputed opinions, please let me know. I like a good conspiracy just as well as the next guy :). Maybe we'll get some more facts on which to base our theories from the criminal trial (in April?). Jerry Jerry (Ico) DOC0217 Subject: Re: normality From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/14 Message-ID: <4dbno6$sjc@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , shogun@interaccess.com (Kevin Squires) says: > >In article <4d9ibb$14fp@bigblue.oit.unc.edu> kferri@email.unc.edu (Karen Ferri) writes: >>From: kferri@email.unc.edu (Karen Ferri) >>Subject: normality >>Date: 14 Jan 1996 00:22:03 GMT > > >>Please pardon this basic question, but I can't recall the facts from my >>college days and I can't find it in my old chemistry books: > >>What is the definition of normality? I need to make a 10 N (not M) NaOH >>solution, but can't remember this definitiion. > >In addition, normality finds its usefulness in titrations. However, I also >have a simple question: For a 1 M H3PO4 solution, what would the normality be >(by definition). I understand that with strong base, all 3 protons would be >pulled off, eluding to a normality of 3N, but the last, in particular, proton >is hard to remove. Does this have any effect on the defined normality of the >solution? You might look at my previous article on this subject. "Normality" very much depends on what reactions are involved. For instance, acetic acid contains 4 hydrogen atoms but only one of them is measurably ionizable. In practice, because of the formal classification of all three hydrogen atoms as ionizable, you would normally label a bottle of 1 molar H3PO4 as 3 normal for the benefit of visiting chemists. However, in your own mind, you might reasonably consider it as 2 normal for purposes of your own titrations. Jerry (Ico) DOC0218 Subject: Re: normality From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/14 Message-ID: <4daa8c$5gh@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4d9ibb$14fp@bigblue.oit.unc.edu>, kferri@email.unc.edu (Karen Ferri) says: > > >Please pardon this basic question, but I can't recall the facts from my >college days and I can't find it in my old chemistry books: > >What is the definition of normality? I need to make a 10 N (not M) NaOH >solution, but can't remember this definitiion. > You certainly came to the right forum with this question. Your mailbox should overflow. In the case of sodium hydroxide solution the normality and molarity are the same because each mole of NaOH provides one mole (or equivalent) of hydroxide ion. We arrive at a value for normality by looking at the number of equivalents each mole represents from the perspective of whatever reaction we are interested in. We multiply the number of equivalents per mole times the molarity to get the normality. Let's take HNO3 as an example. If we are dealing with an acid base reaction we would say that one mole of the acid yields one mole of hydronium ion so one mole is one equivalent and thus the molarity and normality are equal. If we were using the same compound as an oxidizer such that the nitrogen went from the 5+ oxidation state to the elemental nitrogen state of zero, we would multiply the molarity of a solution by 5 to get the the normality or number of equivalents per liter for oxidation purposes. Most often we use normality to describe solutions of acids and bases. This makes it very easy to figure out the number of equivalents per mole. We merely count the active hydrogen atoms in a molecule of acid or the number of hydroxyl radicals associated with a molecule of base. Jerry (Ico) DOC0219 Subject: Re: Oxygen & hydrogen combine??? What exactly happens? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/15 Message-ID: <4dd458$rqd@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <1996Jan15.055131.2397@news.bogo.co.uk>, wheatley@mail.bogo.co.uk (Nigel Wheatley) says: > >You would be quite surprised exactly how much energy! The enthalpy of >formation of water is -286 kJ/mol (this is the amount of energy given >out to produce one mole of water from hydrogen + oxygen: the minus >sign signifies that energy is given out). The heat capacity of steam >is 33.6 J/K/mol, ie. it requires 33.6 J to raise the temperature of 1 >mole of steam by 1 K. This means that enough energy is given out >in the reaction to produce water to raise the temperature of the >product to nearly 9000 K !! > >Well, it doesn't quite because all the many asumptions I've used in >that back-of-the-mouse calculation wouldn't hold at 1000 K let alone >9000 K, but it is little surprise that it soon gets to be a runaway >chain reaction! > >Other loss of energy, other than heat and light, comes in the work >required for the expanding gas to push back the atmosphere, and in the >kinetic energy of the expanding gas: it is this kinetic energy which >results in the thrust to the Shuttle. > You might note that the work expended against the atmosphere is already compensated for in your heat capacity figure which is C(p). One important reason the reaction won't get as hot as calculated lies in the fact that the heat capacity of steam is considerably higher at elevated temperatures where additional degrees of freedom kick in. Also, of course, water dissociates into its elements way below 9,000 K. Jerry (Ico) DOC0220 Subject: Re: Water injection into From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/15 Message-ID: <4de96p$k4o@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <8B8E27B.06230067AA.uuout@execnet.com>, billc@execnet.com (BILLC) says: > >RRJ>Water injection was used (and still is on some old engines) in turbo jet >RRJ>engines to increase the thrust on takeoff. The Boeing KC135 was an example >RRJ>of a aeroplane using this technology. The water has the effect of cooling >RRJ>the gas streem and increasing thrust through expansion. The water injectio >RRJ>systems made the engines much noisier. > >Please, how does cooling a gas stream "increase thrust through >expansion"? > Good question. The only mechanism I can think of is one in which the water is flashed into steam by the heated metal of the engine. One can extract some useful work from energy stored in heated mass. A good example might be the little mining locomotives which run for a long time using an injection of very hot water under high steam pressure. Jerry (Ico) DOC0221 Subject: Re: oklahoma explosive From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/15 Message-ID: <4de8o0$k4o@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <877251112wnr@fats.demon.co.uk>, Richard Bettis says: > >Is there *nothing* that 'Uncle Al' isn't ignorant about. > >You could make a building destroying fuel/air weapon for less than the cost of >the anfo. FAW's are designed for destroying buildings. > >(actually, I work on the 'accidental' scenario of a liquefied gas fuel leak. >Its like FAW's only morally defensible!) > >I would suggest that 'Uncle Al' might try some simple fuel/air experiments in >his back-yard, only I'd probably get sued by his neighbours! > What part of Al's post did you find inaccurate? His remarks concerning FAE seemed quite correct to this reader. Making a reliable fuel-air device requires a great deal of design and test work. If it were a trivial exercise, air blast weapons would not have relied exclusively on condensed explosives for most of this century. The comment about the existance of two seismic waves may or may not be correct, but that is a subject which remains open to debate. Jerry (Ico) Jerry (Ico) DOC0222 Subject: Re: resistance of solution From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/15 Message-ID: <4dd4bb$rqd@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4dcs39$2i8@hemp.imel.kyoto-u.ac.jp>, yoshihar@bird.scphys.kyoto-u.ac.jp says: > > I am measuring resistance of aqueous >solution of KCl.But it increase as time > goes. What is wrong? Or if it is not >wrong ,which point should I use as a >result? Thank you. > I trust you are using high frequency alternating current to avoid the build up of counter EMF by electrolysis products. You should expect constant values with such apparatus. Jerry (Ico) DOC0223 Subject: Re: ammonia powder From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/16 Message-ID: <4dfsr9$nbb@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4dflv1$f77@grid.direct.ca>, tmiller@diachem.com (Tom Miller) says: > >jzhou@nyx.cs.du.edu wrote: >>I have a recipe which calls for the use of "ammonia powder"... > >Post the recipe, its purpose, its origin & date of publication... a >few clues will improve your chances of a quality reply. > I got a request from alt.chinese.txt et al to take them off the distribution list for this thresd unless we post in chinese. Sounds like a good idea to me. Jerry (Ico) DOC0224 Subject: Re: 35% of h2o2 means how many volumes ????? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/17 Message-ID: <4djtfi$edn@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Lev Gorenstein says: > >On 16 Jan 1996, Christophe Morin wrote: > >> >> Je pense qu'il suffit de calculer la molarite de la solution et de >> rapporter cela au volume molaire degage par la decomposition de l'eau >> oxygenee. le ratio donnera le nombre de volumes >> (je ne suis pas le specialiste demande mais j'espere que cela aidera >> quand meme). > >Ce n'est pas vrais. Le "volume" la est le ratios de volumes de H2O and >H2O2 pour la preparation de la solution. > >God, sorry for my poor French and let me switch to English. This >suggestion is not correct. I mean - it's possible to turn it Christophe's >way, but I bet that the original sence was different. All it takes is to >say "Take 1 volume of H2O and X volumes of H2O2". Since the densities of >H2O and H2O2 are quite different (1 and 1.46g/ml, respectively), one needs >to know if the requested 3% is percent by volume or percent by mass, >before getting this number X. > >If it's by volume, then the answer is quite simple - 35% is roughly 1/3, >so you take 1 volume (part) of H2O2 and 2 parts of water. If you need >more precision, solve the equation > > X > Volume % = 0.35 = ----- > X+1 > >If it's by mass, you have to play a little harder ball: > > X*1.46 > Mass % = 0.35 = --------------- > X*1.46 + 1*1 > > >Et voila. > Lev. That's not how it works, Lev. The "volume" referred to is the STP volume of oxygen gas liberated by one volume of H2O2 solution, at least for weak solutions which have a density of approximately 1.0. 100 volume H2O2 solution is equivalent to 30% H2O2 where the percentage is expressed as weight/volume, e.g., kg/L. Watch out because some references express the percentage in the more conventional form of weight/weight. The Merck Index, for instance, says that 30% by weight H2O2 is 100 volume material. Since the liquid has a density of 1.11, this means the yield of oxygen is almost exactly 100L/kg rather than 100L/L. Kingett's Chemical Encyclopedia says the percentage should be calculated as w/v rather than w/w, but fails to note that this could lead to some confusion if one selected the wrong units for w and v :) I would judge that the best bet is to use the system suggested in references such as *Industrial Chemicals* - John Wiley & Sons. Here the strength is expressed in weight percent and the "volume" strength is v/v. Of course you need a table of densities (sigh) to figure out that 100 volume H2O2 is actually 27.5% by weight, not Merck's 30%. Incidently, just to make it a little harder, the eighth edition of Merck printed "30% H2O" rather than 30% H2O2. Welcome to the US. Jerry (Ico) Where is the SI when you need them? Busy making us shift from dynes to Newtons :-< DOC0225 Subject: Re: Cyanide ingestion From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/17 Message-ID: <4djpus$edn@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4dj1c4$maq@ixnews4.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: > >Small amounts of ingested cyanide bind to small amounts of cytochrome at >the terminal end of the respiratory chain. It also gets metabolized to >thiocyanate, which then depresses thyroid function. > >People who suffer chronic ingestion of members of the cabbage family are >ingesting rather large amounts of thiocyanate. The depressed thyroid >function resulting leads to behavioral torpor, obesity, and lowered >intelligence. > >Brussels sprouts not only taste awful, they destroy your mind and body - >dispite being cruciferous vegetables harboring the cure for cancer and >the FDA. > That is very interesting. At least in the "old" days, the colleges at Cambridge served brussel sprouts in hall each day for about six months of every year. The other six months it was leathery green peas. East Anglia is known as the "Brussel sprout capital of the world." BTW, the students apparently were immune to the obesity enhancing effects, generally being notoriously thin. I wonder how much smarter and scrawnier those Cambridge graduates might have been if they had refused the sprouts. Jerry (Ico) DOC0226 Subject: Re: Picric acid safety From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/18 Message-ID: <4dm8u2$3t4@geraldo.cc.utexas.edu> Newsgroups: alt.engr.explosives,sci.chem In article <4dh1up$m95@news.ox.ac.uk>, mert0236@sable.ox.ac.uk (Thomas Womack) says: > >Gerald L. Hurst (glhurst@onr.com) wrote: >: In article <4dbnde$7ov@zinc.compulink.co.uk>, mark@murder.compulink.co.uk (Mark de Roussier) says: > >: We froze the tube above the valve with liquid nitrogen poured >: on a fiberglas wrapping and then cut and flared the tube and >: installed a new valve. The frozen ClF5 seal wasn't a perfect >: fix so a few drops escaped and burst into flame on contact >: with the concrete floor. > >: BTW, it is nice to be able to talk about ClF5 these days. Back >: then it was a classified and otherwise unknown compound which >: we called "compound A" in the cloak-and-dagger atmosphere of >: those cold war space race years. > >What on earth do you use ClF5 for? I can see it's a good oxidiser and >fluorinator (to put it mildly), but I can't see a use for it in the space >race. And how did you classify the interhalogen compounds? 'oh, chlorine >doesn't react with fluorine, and if you try to perform the reaction the >CIA will come and imprison you'? :) > Now I know why we called it "the other place." Most large rockets are propelled by binary propellants, e.g., a fuel and an oxidizer such as liquid oxygen and kerosene (kerosine). About the highest specific impulse is delivered by the combination of liquid fluorine and liquid hydrogen, both of which are devils to handle. ClF5 is a liquid under pressure and chemically (energetically)about as close as one can get to liquid fluorine. ClF5 was, I assume, discovered during work under a government contract, I would guess at Rocketdyne. It was classified by the simple expedient of only disclosing its existence to people who had an appropriate security clearance. Such individuals had signed an agreement not to divulge classified information, often for 12 years, until automatic declassification. In the case of ClF5, it was unlikely anyone would stumble onto it in the lab, because, in typical fashion, many theoretical chemists knew good reasons why it couldn't exist as a stable molecule. Also, the conditions required to synthesize the material were rather extreme considering the nastiness of the starting materials, and thus it was not too likely anyone would stumble onto the compound. Of course, it was known to all that chlorine reacted with fluorine to give ClF and ClF3. BrF5 was known, but was often justified in chemists minds by the larger bromine atom. I believe there were two pilot plant scale methods of manufacture: The batch process which I developed at Aero-Jet General, and a continuous process developed at Rocketdyne. I do not know how successful the latter was, but I can imagine they had their difficulties along the way:) My plant made a total of about four tons of the substance before we finished the contract and shut that juggernaut down. If the stability of ClF5 appears obvious today, that obviousness is probably augumented by a few temporal diopters. Jerry (Ico) DOC0227 Subject: Re: Amonnium Nitrate (& other people's problems) From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/19 Message-ID: <4dovv3$rkj@geraldo.cc.utexas.edu> Newsgroups: rec.pyrotechnics,sci.chem Article Segment 1 of 2 In article , spiegl@lobster.cig.mot.com (Mark Spiegl) says: > >So why does the addition of certain phase stabilizers - KN, ZnO, NiO, >dinitramides, etc - make AN less susceptible to swelling, sintering and >powdering. My laymans (and possibly incorrect) understanding is that the >addition of of these phase stabilizers raises the temperature of the >phase3-phase4 transition into a range which is unlikely to occur during >normal handling and storage. Is this correct? How do the catalytic effects >of water which you described play into this? Obviously, I can't speak for every proposed mechanism, but many of them have been held to be ineffective invalid in later literature or in the unpublished reports of industrial chemistry labs. . Many of the claims concerning "phase stabilization" simply do not work as advertized. However, it is true that certain additives retard the end effect, swelling. My GUESS is that additives change the behaviour of the surface by competing for water or aqueous solution with the AN. Most additives are put on the surface of the AN so that their concentration is very high where the competition is needed. Clay is frequently added as a 2% coating to improve flow and inhibit sticking. Clays can also act as pourous agents to help wick moisture away from prill contact points. Remember that clays (bentonite, China clay) are often used to crosslink aqueous gels and are among the most water adsorptive materials. Other additives may act as surfactants, lowering the surface tension of water and therby again reducing capillary bridging contact. I've studied a few additives on my own. It was once indicated to me that guar gum might inhibit swelling, but was a bit expensive. Thinking by analogy, I tried a series of multiweek tests using ordinary wheat flour as a dusted coating. Sure enough, the samples swelled much less than the controls. It seems likely that those tiny, heterogeneous particles of insoluble carbohydrate worked by the mechanism of binding surface moisture. It is rather easy to see how early researchers might happen to try some relatively esoteric compound like acid magenta and discover "unique" properties of stabilization. People, including my researcher friends with the guar, often do not try the obvious because we are sort of programmed to expect more if the method involves the rare or the expensive. An example: Many years ago there was a major explosives company which manufactured a water-base ammonium nitrate gel explosive which incorporated a very small quantity of ammonium perchlorate (sensitizer), a relatively expensive ingredient as commercial explosive ingredients go. When the formulation was called to my attention because of a material availability problem, I got a big grin by sending the client a memo which said: You are putting AN, sodium nitrate and ammonium perchlorate in your formulation. Ammonium perchlorate is much more expensive than sodium perchlorate. If you use sodium perchlorate in place of ammonium perchlorate, you can get exactly the same final composition (mix of ions) at a lower price and with fewer supply problems. In particular, you can use raw sodium perchlorate liquor, which is even cheaper, because the manufacturer doesn't have to dry it. The research group at that company had over 50 scientists and technicians working on a daily basis on explosives formulation and manufacturing problems. The tip I gave them might have come off of an early page in a freshman chemistry text. The people I was helping were nothing less than well educated and competent, but in the press of solving difficult problems they had all overlooked the cheap, easy and obvious solution to an ongoing problem in a major tonnage mainline product. DOC0228 Subject: Re: Amonnium Nitrate (& other people's problems) From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/19 Message-ID: <4dovv3$rkj@geraldo.cc.utexas.edu> Article Segment 2 of 2 Second example: Also many years ago, a large explosives company had designed a delay primer which was initiated by a line of detonating cord through a tube along the cylindrical side of the charge. A delay cap was located in the body of the charge and required the conduction of the shockwave from the cord via a low-energy shock tube such as Nonel. The problem was that Nonel and its patent belonged to someone else. I suggested to the research group: "why don't you just use a hollow tube?" It worked. As it turned out, for distances of several inches, a hollow tube with no explosive on its surface (a la Nonel) will happily transmit a more than adequate amount of shock energy around a couple of right angle bends and still reliably initiate a delay element. Had there been no anticipated trouble getting and using Nonel, that's what would have been used at greater cost. Had this happened, it would be taken for granted still today that an explosive coating was necessary. Why did these simple solutions come from a consultant and not from within the groups working daily on the problem? The answer to that question is simply that any consultant has the advantage of fresh perspective on OTHER PEOPLES PROBLEMS. Where consultants need help is in the swamp of their own personal jungles. It helps also to remember that simple information is more highly valued when you have to pay an expensive consultant for it.I have also earned my wages by simply advising management to listen to the advice of one of their own employees who had been trying unsuccessfully to get their attention for a long time. I suppose it is human nature to undervalue or ignore that which isn't expensive, difficult or rare and to try to apply quantum mechanics where Popular Mechanix will suffice. I know that I have been guilty all my life of overlooking the obvious. Jerry (Ico) DOC0229 Subject: Re: CaHCl From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/20 Message-ID: <4dpu05$na6@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , DeAx (hm...) says: > >Uhhhhhhh, > >A little bit of nonsence????????????????? > >Could you immagine a stable species containing Ca(2+) H(+) and only one Cl(-)? > No, but Ca(2+), H(-) and Cl(-) doesn't really bother me. At least as a thought experiment, I see nothing glaringly wrong with reacting calcium hydride and calcium chloride to get a double salt. Jerry (Ico) DOC0230 Subject: Re: Fresh water from sea water - new economical process From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/22 Message-ID: <4e105s$90r@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.engr,sci.engr.chem,sci.chem,sci.misc,sci.research In article <4e0jp7$dg0@columbia.acc.brad.ac.uk>, ajkamphu@bradford.ac.uk (AJ KAMPHUIS) says: > >Gerald L. Hurst (glhurst@onr.com) wrote: > >: The question is whether CO2 rapidly >: escaping from seawater can freeze substantially more water than >: can be accounted for by the accepted heat of solution of the >: escaping CO2 and the heat of vaporization of the calculated >: equilibrium water vapor entrained therein. > >Has anyone considered the temperature decrease due to adiabatic >expansion (of the CO2), as an additional source of cooling There is no need to. That energy is included in the enthalpy change. Remember that DeltaH = DeltaE + Delta(PV). Jerry (Ico) DOC0231 Subject: Re: low temp flames? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/22 Message-ID: <4e0vj7$90r@geraldo.cc.utexas.edu> Newsgroups: rec.pyrotechnics,sci.chem In article <4drtj2$6pc@ccnet3.ccnet.com>, berniew@ccnet.com (Bernie Willis) says: > >Michael Freiert wrote: >> i know some liquids burn at low temperatures (ie 70-110 F of >> around 30 C for you metric people) > >At what point do we draw the line between burning and simply oxidizing? > If it isn't hot enough to be capable of producing black body visible light, it isn't burning or deflagrating. Dull red light emission begins around 500 deg C. Now try the more difficult task of defining the difference between simple oxidation and combustion. I would say that combustion (which includes burning and deflagration as a subset) usually but not always connotes the emission of light, but not necessarily in the form of black body radiation. Cool flame combustion may be luminous below 300 degC. Combustion appears also to be a useable term where there is no (visible) light emission but the combusting substance disappears as a result of the reaction. A hypothetical example of such a reaction would be one which otherwise had the properties of cool flame combustion but lacked the specific electron transitions resulting in luminosity. All forms of combustion require thermal feedback from the energy of their reactions to sustain them in the absence of insulation and usually in the presence of substantial gas flow or reaction zone movement. Simple oxidation may be thought of as occurring at the temperature of the surrounding environment without feedback from the heat of reaction raising the temperature significantly above that of the environment.. The reaction of unsaturated oils in a pile of rags is a form of oxidation which does rely reaction energy feedback without producing visible radiation until the rags burst into flame. We call the entire process autocombustion, but the initial reaction is virtually the same as the drying of oil-base paint, which hardly qualifies as "combustion." We can at best now invoke the fact that the substrate is not "consumed" in the initial reaction to avoid the "combustion" classification. There are also numerous cases of catalytic oxidation which may occur with or without light emission. In describing these reactions, the distinction between oxidation and combustion seems extremely arbitrary since it depends often on merely how far we turn the feed valve - enough to make the catalyst glow or not? It might be argued that the dividing line in this sort of process is set by whether or not the energy feedback is a primary agent in determining the reaction rate. I guess it boils down to the frequently encountered principle that we know it when we see it, but it's hard to define unambiguously. Please do not succumb to the temptation to invoke Webster as the FINAL authority in this discussion. Dictionary definitions are rarely adequate to describe technical shades of gray. Words have a way of gathering different connotations in different areas of the arts and sciences. We sometimes need to listen to hear what they seem to mean in our art, and then sometimes create new conceptual fine structure by mutual agreement. I have not defined "combustion," and the related terms above. I have merely tried to describe what the terms mean to me, along with some of the ambiguities. Others will surely have a different perspective. The initial authoritative tone above was adopted to ensure some combative spirit in the replies :) Jerry (Ico) < DOC0232 Subject: Re: Solubility of NO2 in water From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/23 Message-ID: <4e25cs$arg@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.engr.chem In article <31046700.6941@superlink.net>, Eric Lucas says: > >Frank Koch wrote: >> >> Hello! >> >> Who can help me? >> >> I am looking for the solubility of NO2/N2O4 in water. I need values for >> different temperatures. Perhaps anyone can deal with a Henry-consant if >> one exists. I am not sure if the Henry-law is applicable since NO2 >> reacts with the water forming HNO3. But perhaps there is a maximum >> concentration one can reach when NO2 is bubbled through water (and that >> changes with the temperatures). >> > >NO2 + H2O ---> HNO3? > >Does this really occur? It represents and oxidation of N and would >have to be accompanied by reduction (or disproportionation). If its >a reduction of water, it must be giving off H2, and I didn't think >NO2 had anything like the required reducing power. If >disproportionation, it would have to give HNO2, but I believe HNO2 >and HNO3 react to give a brown gas--presumably a mixture of NO2 and >N2O4. > Try it this way: 2NO2 + H2O <-> HNO3 + HNO2 at low temperatures, then on warming: 3HNO2 <--> HNO3 + 2NO + H2O Then of course the NO can further go: 3NO <--> N2O + NO2 and if there is any oxygen about: 2NO + O2 <--> 2NO2 Nice system to keep one busy. Jerry (Ico) DOC0233 Subject: Re: Blending Talcolm Powder From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/24 Message-ID: <4e6c9s$45d@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4e68bp$9me@lijgate.lij.edu>, Kaminie Amarjit says: > >Forgive my ignorance,but what is a waring blender. Is it a regular >blender you use in the kitchen. > "Waring" is a trade name which has become colloquially generic for all makes of high-speed kitchen blenders. The brand name is especially common among chemists because the company also makes stainless steel models for laboratories. Personally, I always used Oesterizer mixers or their OEM cousins because they have Mason Jar standard threads. This gives one the option of using upside-down canning jars as mixing vessels and can save a lot of trouble in clean up when working with a lot of gunky materials. Once the material is blended, simply screw on a lid and the product is ready for storage. For the next batch you use another 50 cent jar. With liquids, it helps to have a couple of spare blade assemblies and to buy silicone gaskets (for organics). I used to soak my gaskets in solvent to leach out the plasticizers and thereby avoid contamination of sensitive organic mixes. For talcum powder, any mixer should make uniform blending a piece of cake (easy). Jerry (Ico) Jerr DOC0234 Subject: Re: Blending Talcolm Powder From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/24 Message-ID: <4e5vff$r1h@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4e5nh2$290@lijgate.lij.edu>, Kaminie Amarjit says: > >Can someone suggest the best procedure for blending talcolm powder( baby >powder) with a red synthetic dye(red lake) on a home made basis. > >-- > >This message represents the personal views and opinions of the individual >sender and shouldin no way be construed as an authorized communication >on behalf of Long Island JewishMedical Center. > How about a Waring blender? Jerry (Ico) DOC0235 Subject: Re: Fresh water from sea water - new economical process From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/24 Message-ID: <4e4rkk$7s5@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.engr,sci.engr.chem,sci.chem,sci.misc,sci.research In article <31043335.1295186@news.rmci.net>, jvinson@rmci.net (John W. Vinson) says: > >ajkamphu@bradford.ac.uk (AJ KAMPHUIS) wrote: > >>Gerald L. Hurst (glhurst@onr.com) wrote: >> >>: The question is whether CO2 rapidly >>: escaping from seawater can freeze substantially more water than >>: can be accounted for by the accepted heat of solution of the >>: escaping CO2 and the heat of vaporization of the calculated >>: equilibrium water vapor entrained therein. >> >>Has anyone considered the temperature decrease due to adiabatic >>expansion (of the CO2), as an additional source of cooling > >Youxue Zhang has an article in _Nature_ (379:57, 4 January 1996) about >the Lake Nyos disaster in 1986. To quote: "an estimated (1-3)x10^8 kg >of CO2 was released during an eruption that possibly lasted as long as >4.5 hours". If this "new economical process" were to be working as >well as claimed Lake Nyos would have become Nyos Glacier. Later in >the article, Zhang notes: "Because of the high heat capacity of >water, the temperature decrease due to gas exsolution and expansion is >small (the temperature decrease is estimated as ~4 C if P(0) is 2.0 >MPa and final P is 0.1 MPa)." > >Perhaps the injection of some real numbers and algebra would further >this discussion. Careful with those quotes, John. The clipped paragraph suggests that I am asking whether CO2 can do what is alleged in the patent. No way in my opinion. What do you mean by "the injection of some real numbers and algebra"? Weren't the thermodynamic calculations using accepted enthalpy values for CO2 solutions "real" enough? Not one shred of quantitative evidnce has been published to to the contrary. What kind of algebra do you expect to overcome the absurd conclusions I demonstrated would arise out of the inventors claim in light of the CALCULATED thermodynamic consequences. One of those algebraically calculated bottom lines, based on accepted enthalpy data, showed that if the invention works as described, The opening of a can of Coca Cola at 0 defC would cause a serious risk of scalding the hand that opened it. That experiment has been run at least several million times without any reports of live steam rushing out of the can. Jerry (Ico) Jerry (Ico) < DOC0236 Subject: Re: Melting rate of ice cubes From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/24 Message-ID: <4e4qc3$2qh@geraldo.cc.utexas.edu> Newsgroups: sci.chem Article Segment 1 of 2 In article , jbednarc@sisnet.ssku.k12.ca.us (Jennifer Bednarczyk) says: > >To whom it may concern: > I am a student at Mt. Shasta High School in CA. I am trying to find >research for my project which is 'How does the surface area of an ice cube >affect the melting rate?' Now the abvious answer is that the smaller the >size of the ice cube, the faster it melts but I need background research >to help me understand the scientific reason for this. If you have any >helpful information please reply to me at the following e-mail address~ >jbednarc@sisnet.ssku.k12.ca.us Thank-you. > ~Jennifer Bednarczyk~ Try this approach: The time it takes to melt an ice cube (T) depends directly on how much volume (V) of ice you have to melt and inversely on how much surface (S) there is present for the heat to get into the ice. The more ice you have to melt, the longer it takes and the more surface the ice has, the less time it takes. We translate these English statements into the following little algebraic equation: 1) T = K*V/S Where K is some constant we do not need to know the value of for our general analysis. An ice "cube" or any other "shape" such as, say, a pyramid or a horse has a very interesting individual property associated with it which we will call the "shape constant" (SC), such that for any given shape, including that of an ice "cube" the relationship between the surface of the shape and its volume is given by the expression: 2) S = SC*V^(2/3) (surface = shape constant times the volume raised to the 2/3 power) and this equation holds for any size as long as we are talking about the same shape. Now believe it or not, there is a good chance that your teacher never heard of the shape constant, but it is the sort of thing that makes people who see it say. "Hmm, now that I think of it that equation is obviously (or intuitively) true. Sometimes they will even try it out to see if it works for two different sized cubes or spheres or the like. It does work. SC is equal to 6 for a cube and 4.836 for a sphere, which is as small as it gets. We don't really care what the value for an ice "cube" is, but it is obviously close to 6. Now for the cool part (a little humor there). Substitute the value of S in equation 2 for the S term in equation 1 to get: 3) T = K/SC*V^(1/3) Since we don't really care what the values of SC and K are, we can simply define a new constant (A): 4) A= K/SC And substitute it into 3 to get the very simple equation: 5) T = A*V^(1/3) Now another nice property of any "shape" is that the length of any arbitrary line between two corresponding parts of the object, such as the tips of a horses ears, is proportional to the cube root of the volume of the horse (shape). This is equally true for, say, the length or width or diagonal across the top of an ice "cube" of any shape. Let's call whatever line we choose "L" for length, then we can write: 6) V^(1/3) = B*L where B is again a constant for any given shape. OK, now we simply replace the more ungainly term, V^(1/3) in equation 5 with its value in equation 6 (B*L) to get: 7) T = A*B*L And since we once again don't care what the values of the constants A and B are, we let their product A*B = C and substitute this new constant into equation 7. TA DAAAA! 8) T = CL How about that? It turns out that the time required to thaw an ice cube of given shape is proportional to the length (or width or height, etc.) of the cube. So if a one-inch "cube" thaws in one hour then a two-inch "cube" should take 2 hours, even though it is eight times as big in volume and weight. If you want to express this as a rate, the expression is simply C = T/L which gives the melting rate in length units per unit time and should be valid for all "cubes" of the same shape. DOC0237 Subject: Re: Melting rate of ice cubes From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/24 Message-ID: <4e4qc3$2qh@geraldo.cc.utexas.edu> Article Segment 2 of 2 Remember that C is a combination of several constants which we chose to ignore as far as actual individual values go, but if you expand your final equation back to include all those constants you will find that that equation defines a universal rate of melting valid for all shapes and sizes, depending only on that original shape constant (SC) and that other constant B, which is also a sort of "shape constant." But unlike SC it is one which depends on your choice of arbitrary points on the particular shape. Naturally, you would have to make at least one careful experiment under reproducible conditions of temperature, ventilation, and even relative humidity to get the necessary value for that original K constant. What we have derived here is a mathematical model which we hope will conform to reality. In practice such models work better sometimes than others, mainly because we can never really guarantee that "all other things are equal" in our experiments. The next stage would be to test the theory to see how good the model is. Good luck. Jerry (Ico) DOC0238 Subject: Re: Archival Plastics From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/26 Message-ID: <4e9tc6$lat@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4e86ct$ire@ixnews6.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: > >Mylar is Dacron or PET - poly(ethyleneterephthalate). There is no >plasticizer or halogen in Mylar, it is remarkably resistant to UV >degradation, it is strong and tough, it has a very low gas and water >vapor permeability, and it heat seals - good stuff! "Mylar" is duPont's trade name for THEIR polyester film. Credit should go to 3-M for this class of product as they were the pioneers with Skotch-pak (R). Heat-sealable? My experience is that despite the listings in charts of "heat-sealibility" in the 425-450 degF range for "some" PETs, the material one ends up using is a laminate or coextrusion with a polyethylene or blend resin as a heat-seal coat. Again, hats off to 3-M for this innovation of the sixties. Jerry (Ico) DOC0239 Subject: Re: Endothermic Reactions From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/26 Message-ID: <4e9qv9$lat@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4e83b9$chq@vixen.cso.uiuc.edu>, stinky says: > >I can't believe you said that, because it is absolutely, positively untrue. >Since enthalpy for endothermic reactions is positive you need a large positive >entropy change to overcome it. So spontaneous endothermic reactions usually >involve some chemical species in the condensed phase changing into some >chemical species in the gas phase, like > > HgO(s) -------> Hg(l) + 1/2 O2(g) > >and there are plenty more like that. I found this one in a general chemistry >text. > If you are referring to the article by jyri_r@madli.ut.ee (Jyri Ruut), you better poke your nose back into that book and think again. What the man wrote is correct, and you picked a lousy example to try to disprove it. Jyri's article is quoted below for the benefit of those who have no idea to what you were referring. Jerry (Ico) ****** Begin quote: Newsgroups: sci.chem Subject: Re: Endothermic Reactions Date: 25 Jan 1996 07:27:16 GMT Organization: Tartu University, Estonia Lines: 21 Message-ID: <4e7bck$hja@kadri.ut.ee> References: <4d7met$c7e@cloner2.ix.netcom.com> <4d8n7a$r20@ixnews6.ix.netcom.com> <4dlspv$5q7@soap.news.pipex.net> NNTP-Posting-Host: madli.ut.ee X-Newsreader: TIN [version 1.2 PL2] John Williams (j.williams@bbcnc.org.uk) wrote: : All these examples are phase changes. Anyone got a simple *reaction* : i.e. a chemical change takes place? Endothermic reactions need continuous flow of energy from the outer environment. Commonly, one gets this energy from some kind of heating device. Without additional energy, these reactions won't go, i.e., one can't observe the reaction going and the temperature dropping and dropping. Activation energy is needed to initiate the reaction and surplus amount of energy to keep the endothermic reaction going. In addition, reaction rates drop dramatically with decrease of temperature. DOC0240 Subject: Re: HELP!!! superfluidity/liquid helium From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/26 Message-ID: <4e9ppl$lat@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4e73cn$2832@news.doit.wisc.edu>, Netscape User says: > >I guess the Utah State University does have a library with quite a couple of books >about chemistry. What about a visit over there and some questions following this >visit, if you didn't understand something? I hope you don't expect that I write you >a couple of pages back about this or even your whole paper??? > Dear Netscape User, Please see my reply to Username unless you are Username. Jerry (Ico) < DOC0241 Subject: Re: HELP!!! superfluidity/liquid helium From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/26 Message-ID: <4e9ph0$lat@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4e8fn0$o41@vixen.cso.uiuc.edu>, Username says: > >If your paper is really only one page you could make the whole thing up or >just use a lot of long words that say nothing. If you would like facts may >I suggest going to the library. They have many nice books that should be >rather helpful. >Why on earth would somone post their homework on the net and expect others >to do it for them? Answer: because people on the net are so ready to show >"how much they know (or can read)" that they dont care that they are being >irresponsible by doing so. Both the homework posters and answerers should >be ashamed of themselves. > That's a fine lecture for a fellow named "username," who doesn't believe in quoting an introductory line. Why waste the time and space giving us your unsolicited opinion on the shamefulness of our exercise of the right to decide what we do and do not answer. The question regarding liquid helium is of enough general interest to warrant answering even if it serves some nefarious teenager's scheme to avoid an hour of homework. At least it relates to physics, which is more than I can say for your whining post and my snippy retort. Jerry (Ico) DOC0242 Subject: Re: Molar masses does't work. From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/26 Message-ID: <4e9v7o$lat@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4e8m6v$bgn@hawk.pix.za>, nt000001@pixie.co.za (Nicola Toma) says: > >Email: nt000001@pixie.co.za > >Can someone please explain to me why a mixture of potassium nitrate, >sulphur and sugar using calculated molar mases from the exation for >its combustion reaction does not work at all? > >Is it because some of the sulphur forms SO2 instead of reacting with >the potassium nitrate to form K2S to free excess oxygen. > >There is alot of carbon left after the reaction (if I can get it to >react at all!) which seems to support my theory. > >Am I right? If so please suggest a possible solution to rectify the >problem. > How are we supposed to know what proportions you used in order to judge what is wrong? If you are expecting a simple reaction from this mix, you may be surprised. Have you looked at the reported reactions of black powder? They are quite complex and the products tend to be a gawdawful mess of things which look like they ought to bounce down to a lower overall enthalpy state but don't. Why should sugar be any better than charcoal? Don't hold your breath until SO2 gives up its sulfur to form K2S. How much K2SO4 are you expecting? CO, K2CO3, H2S, S? Particle size and intimacy of mixing have a lot to do with it too. The catch is that it is not healthy to grind such materials together if you value your skin. From a pyrotechnic point of view, why bother with this inferior mixture? Jerry (Ico) DOC0243 Subject: Re: Vapor Pressure Determination From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/26 Message-ID: <4e9u16$lat@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4e86jd$ire@ixnews6.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: > >For a one-shot determination, one need merely introduce a small quantity >of the test subject into a mercury barometer. The bolus will float to >the top of the Hg column, vaporize, equilibrate at temperature, and you >read off the vapor pressure (there must be residual liquid phase) as the >difference in column height. > >Of course, for the SECOND sample, you must disassemble and clean the >barometer, and reassemble it. You safety people will have a conniption >fit (or take out a hunting license). > If you have a friend with a vacuum line, get him to run your vapor pressure - at least a few points for a logP vs 1/T plot. If you do it yourself, make a mercury manometer attached to a cold trap which can be pumped down with your volatile material frozen down in liquid N2 or CO2 depending on just how volatile it is. You can measure the vapor pressure by immersing the trap in dewars of liquid, preferably slush baths at a whole bunch of temperatures to get a marvelous straight line of LogP vs (1/T). You can use the mercury flask as a reservoir if you wish, so that when you are through all you have to do is release the vacuum and restopper the flask. Jerry (Ico) DOC0244 Subject: Re: Why is this pH 13+? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/27 Message-ID: <4ecged$iud@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4ebkse$9fc@treasure.coastalnet.com>, 47jv59wl@coastalnet.com@abaco says: > >Can anyone explain how an aqueous solution that is 99% KNO3, NaNO2, & NaNO3 >at +400F have a pH of +13? I have a customer who says it is. Where are the >-OH ions coming from? There certainly can't be enough in the water. > Why not pH 13? If it's 99% metal nitrates and nitrites at a temperature nearly 200 degF above the normal boiling point of water, it is hardly an "aqueous" solution. A high pH just means there is little hydronium ion present. Maybe the hydronium figured there was no sense hanging around after the water left. A high pH simply denotes a low concentration of H+. If that low concentration of H+ occurs in water, there is a corollary effect that the concentration OH- must go up. Your toothbrush, however, may well contain less than 1X10^-13 moles of H+ per liter of melted plastic at 400 degF, but that does not imply that it contains a lot of hydroxyl ion. Come to think of it, the pH of hot mercury is probably nearly as high as that of the space in an empty beaker :) Jerry (Ico) DOC0245 Subject: Re: Who to complain to about Plutonium. From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/28 Message-ID: <4eepjg$1u9@geraldo.cc.utexas.edu> Newsgroups: sci.bio.misc,misc.invest.stocks,sci.bio.ethology,sci.astro,sci.math,sci.skeptic,sci.chem,rec.arts.movies.current-films,rec.bicycles.tech,alt.c In article <822791917snz@deltrak.demon.co.uk>, Andrew Stephenson says: >He has his own group for his own doctrines, yet he habitually >cross-posts them to groups where they rarely have any relevance. > >People who try to point out what a rotten situation this is get >yelled at for infringing rights. > >The Question: What's wrong with this picture? ;-) What's wrong with this picture? The artist has the wrong perspective. Archimedes' posts have at least a much relevance to chemistry as those of his detractors and he is usually a darned sight more entertaining. Personally, I read his posts when it pleases me Just as I read the complaints at my discretion. I see no real harm in either his posts or yours. When the chemistry is slow we can always tune in on the Lilliputian war to see which end of the egg is being cracked. Then, there is always the possibility that Mr. Plutonium's unfettered ideas may inspire one of us more convervative adherents of conventional science to take wing on a flight of fancy and knock the socks off of academe. One aspect of this whole debate which I fail to understand is why it is so difficult for so many to grasp the idea that the only freedom of speech which is worth a damn is the freedom to express controversial ideas. Even Big Brother usually allows the freedom to sing his praises. Chemistry doesn't belong to any one group, not even chemists. Who should decide what's proper or improper here? Other forums develop moderated groups or exclusive email groups for those participants who want to limit the breadth of material to which they are exposed. Some of us prefer a more open forum where the rabble get to chuck vegetables at the performers. Sci.chem is and should be such a forum. Please do not let my comments suggest that any of you go away. Archimedes value on this stage would be diminished by the absence of his devoted critics and their continuing frustrations and machinations. All that is missing is a transcript of the various conversations which must take place among the powers-that-be at Dartmouth from time to time. They have a difficult problem, and I am sure many in this forum appreciate the fact that they have thus far resisted invoking censorship in the face of what must be considerable pressure from understandably offended and wannabe offended parties. May they continue to resist. The aftermath of any move to deny Archimedes access to this and other groups would probably leave us all waiting for the other shoe to drop. Jerry (Ico) DOC0246 Subject: Re: Who to complain to about Plutonium. From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/28 Message-ID: <4egpje$d1g@geraldo.cc.utexas.edu> Newsgroups: sci.bio.misc,misc.invest.stocks,sci.bio.ethology,sci.astro,sci.math,sci.skeptic,sci.chem,rec.arts.movies.current-films,rec.bicycles.tech In article <310B9360.158E@physics.carleton.ca>, Mike Doncheski says: > >Gerald L. Hurst wrote: >> What's wrong with this picture? The artist has the wrong >> perspective. Archimedes' posts have at least a much relevance >> to chemistry as those of his detractors and he is usually a >> darned sight more entertaining. Personally, I read his posts >> when it pleases me Just as I read the complaints at my >> discretion. >> > >The same could be said of you... Myopic people are also entitle'. >Plutonium occasionally posts things >of relevance to sci.physics and the rec.bicycle.* groups. The >message to which Andrew Stephenson replied belonged to a thread >in the sci.physics.* groups (yes, I just checked this). Mr. Plutonium >removed the sci.physics groups from the newsgroup: line and in their >place added: > > sci.bio.misc, misc.invest.stocks, sci.bio.ethology, > sci.astro, sci.math, sci.skeptic, sci.chem, > rec.arts.movies.current-films, rec.bicycles.tech > I don't blame you for feeling slighted. I'm sure Mr. Plutonium would not object to your copying his post in sci.physics. Perhaps his "Newsgroups" line is limited or maybe he simply made an error. I'm sure he would not deliberately omit one of his favorite forums, especially now that you have called it to his attention. Jerry (Ico) DOC0247 Subject: Re: Pressure of liquid N2 at room temprature. From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/29 Message-ID: <4ej8nv$4vb@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , mdudley@brbbs.brbbs.com (MARSHALL DUDLEY) says: > >jvinson@rmci.net (John W. Vinson) writes: > >-> I think the reason that the constants apply only up to -113 C is that >-> this is the triple point of liquid N2. Anywhere above this >-> temperature there *is* no liquid phase at *any* pressure. I suggest >-> you investigate some other medium for your application... > >Huh? Let us do a reality check here. The triple point of water is I believe >.15 C. If what you are saying is true then water could not exist at room >temperature. I checked my CRC and it indicates that there is NO triple point >for N2. I'm not sure what that means except that at extremely high pressures >it sublimes dirctly from solid to gas like dry ice does. > The triple point of N2 is -210.002 degC per Lange's 13th ed. One of my engineers once tried to defrost a SS tank full of liquid F2 a few decades back. As the crew dived out of the pilot plant, one of them saw the pressure rapidly passing the 4,000 psi mark before the explosion. The tank (cylinder) probably had a burst strength of over 15,OOO psi, but that would have been butter for a wall-to-wall liquid heading for its critical temperarure. Jerry (Ico) Jerry (Ico) DOC0248 Subject: Re: What is the freezing point of water??? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/29 Message-ID: <4ej95a$4vb@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4eit1h$ndo@central.bldrdoc.gov>, aharvey@boulder.nist.gov (3555) says: > >In article <310B3053.6690@Brown.edu> KJK@Brown.edu writes: >>the celcius scale -- another of the multitudinous arbitrary scales -- is defined (or limited) >>by the melting point and frezing point. So we ca just write: >> >> _ >>O degrees = freezing/melting point of water >> >> _ >>100 degrees = boiling point/condensation point of water. > >Actually, for those who are into to semi-trivial details, the above is >no longer correct. International standards now define Celsius >temperatures strictly as Kelvins minus 273.15 (no reference to water >there). And Kelvins is defined solely by defining the temperature of >the triple point of water to be 273.16 Kelvins - the temperature scale >is then defined strictly by thermodynamics without references to any >properties of substances. > >As a result of all this, as of the adoption of the International >Temperature Scale of 1990, the boiling temperature of water at 1 >atmosphere pressure is approximately 99.974 degrees Celsius, and the >melting point at 1 atm. turns out to be about 0.002 degrees C. Close >enough to the old definitions for most purposes. > >Allan Harvey, Thermophysics Division, NIST, aharvey@boulder.nist.gov >"Don't blame the government for what I say, or vice-versa." And for those into even more trivial details, the freezing point and boiling point of water are still 0 and 100 degC respectively to the accuracy stated. They are also absolutely correct for those who do not recognize "international authorities." Jerry (Ico) Sometimes out of step in the march of science, but always good enough for government work. DOC0249 Subject: Re: Why is this pH 13+? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/01/29 Message-ID: <4ehlgu$3mm@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4ehaid$crd@morgoth.sfu.ca>, David Naugler says: > >glhurst@onr.com (Gerald L. Hurst) wrote: >>In article <4ebkse$9fc@treasure.coastalnet.com>, 47jv59wl@coastalnet.com@abaco says: >>> >>>Can anyone explain how an aqueous solution that is 99% KNO3, NaNO2, & NaNO3 >>>at +400F have a pH of +13? I have a customer who says it is. Where are the >>>-OH ions coming from? There certainly can't be enough in the water. >>> >>Why not pH 13? If it's 99% metal nitrates and nitrites at a >>temperature nearly 200 degF above the normal boiling point >>of water, it is hardly an "aqueous" solution. > >The pH of a solution is only properly defined for a truely aqueous system in which it >can be said that [H+][OH-]=10^-14. It may be true that at +400F and 99% alkali nitrate >and nitrite salts, we have a nonaqueous system. In this case, any serious student of >chemical equilibria would throw away the concept of pH and reformulate the equilibrium >problem in terms of the various species present and their free energies of formation >under the conditions of temperature and pressure actualy obtained. > >It may safely be said that the concept of pH causes brain damage in those who fail to >progress beyond first year chemistry. > You're right. I checked the pH of my melted toothbrush and empty beaker with litmus pH paper. It turned brown in the plastic and refused to change color in the empty beaker, so clearly the theory does not extend to these materials. Thank you for clarifying the matter. Now I can cancel the experiments I had planned with the bowling ball. Jerry (Ico) DOC0250 Subject: Re: Volcano From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/17 Message-ID: <4g5inr$no4@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4g5ajg$ahn@uucp.intac.com>, mdunkel@intac.com says: > >Does anyone know how to prepare a "volcano"? I remember seeing it done >some years ago and remember that it used household chemicals and was >safe. My grandson, a budding chemist of six, expressed interes and I >would like to run it for him. > Sure. Mix iron filings with sulfur powder and add a little water to form a thick mud. The reaction Fe + S -> FeS will begin shortly, generating enough heat to cause gentle steam formation with a very satisfying "Galooop" sound of cooking oatmeal. If you cover a cup or so of the mixture with some earth you will get a fine "volcano" effect. Based on the equation above you need about a 56:32 ratio of iron to sulfur by weight. The water serves as a catalyst and of course as the converter of heat to mechanical energy and source of steam. Jerry (Ico) DOC0251 Subject: Re: Analog of Capillary condensation From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/18 Message-ID: <4g6fvk$749@geraldo.cc.utexas.edu> Newsgroups: sci.engr.chem,sci.chem In article <31269CD4.72E4@gold.tc.umn.edu>, "Patrick K. Notz" says: > >JTW8150 wrote: >> >> I am curious to know if anyone has ever heard of "capillary >> solidification". That is the increase in the liquid boiling point when a >> liquid is confined in a small pore. I think this would be the analog of >> capillary condensation ie the increase the boiling point of a vapor that >> is confined in a small pore such that the vapor condenses to the liquid >> state. > >I am not particularily familiar with "capillary solidification" but it could be >the result of the pressure differential (that is, capillary pressure) across the >meniscus (assuming one exists). Depending on the liquid-solid pair, the pressure >drop could be positive or negative giving rise to a boiling point elevation or >declination... this idea doesn't seem to mesh with you capillary condensation >idea tho. > I am not sure I understand what is being asked, but let me make a stab at what I think may be some pertinent information. Imagine water in a capillary which it does not wet, i.e., in which it has a convex meniscus. The supface tension of the curved water- air interface will create a surface pressure which increases in inverse proportion to the diameter of the capillary. At modest diameters in the micron range the surface pressure is of the order of a few psi or thereabouts and results in a very slight increase in the vapor pressure of the water and a modest increase in the boiling point. As the capillary size is reduced to, near atomic dimensions, say of the order of 10exp-7 cm, the surface pressure may rise to a few thousand psi. Although the vapor pressure is significantly higher than the normal vapor pressure under these conditions, the net effect is to very greatly increase the initial boiling point. However, if two segments of liquid were separated by either an air or vacuum space, I would expect them to be propelled apart against external atmospheric pressure well below the normal boiling point. One could say that the liquid then had TWO boiling points. Suppose, however that the water does wet the capillary. Then, we can imagine that the water column is under tension of as much as several thousand psi. It cannot, however fly apart because its tensile strength is still greater than the net surface tension effects. Will the initial boiling point be reduced? In small, smooth capillaries using very pure water, I would guess that the initial boiling point, even under tension would be increased rather than decreased in most cases because of the absence of nucleation sites and the difficulty of forming the initial bubble. Once a bubble was in place between two segments, though, the pressure between the two should be reduced slightly because of column tension, and, from the standpoint of the two opposing menisci, the boiling point could be said to be increased over that of the normal liquid It may be that the phenomena I have proposed above were at least in PART responsible for the erroneous discovery of "polywater." This is a personal theory and welcomes criticism. If there were phases present in the capillary near their freezing points, the capillary pressure or tension could well be sufficient to cause solidification. Water,for instance should freeze a little above zero degrees C under tension whereas most materials would freeze at slightly higher temperatures under pressure. Jerry (Ico) DOC0252 Subject: Re: HELP PLEASE!!! From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/18 Message-ID: <4g8a24$i7l@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3127941A.20B9@cris.com>, "Paul R. Ferreira" says: > >Hi there, > >I'm a college student and I'm stuck with a simple problem. The problem >says: > > For the formation of ammonia from hydrogen and nitrogen, if the > ammonia concentration is increasing at a rate of 0.024 mole/L > sec, what is the rate of disappearance of hydrogen. > >I know rate = k[conc]² > I should probably leave this one alone since Mr. Ferreira obviously hasn't given the problem much thought. Sigh. N2 + 3H2 --> 2NH3 makes it pretty obvious that hydrogen molecules disappear at 3/2 the rate at which ammonia molecules are formed. Your rate equation and the concentrations of the molecular species have nothing to do with solving the problem as stated. You are looking for a complicated answer to a simple problem. Jerry (Ico) DOC0253 Subject: Re: Science Fair Cold Pack Salts From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/18 Message-ID: <4g8d5t$i7l@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4g849e$4j6q@news-s01.ny.us.ibm.net>, schapir@ibm.net says: > >I'm a 7th grader working on a science fair project. I have several questions >reguarding salts. >1) What kinds of salts are used in cold packs? >2) How do they make the water get colder? >3) Why doesn't table salt make the water get colder? >4) Are there any salts that make the water get hotter? More freebee homework problems, eh? 1) Most often ammonium nitrate, NH4NO3 2) This particular salt and numerous others require more energy to break up the crystal lattice into ions than is gained from the energy of hydration of those ions as they attach themselves to water molecules. The driving] force which causes dissolution in the face of having to absorb energy is the increase in entropy. 3) The hydration energy is roughly equal to the crystal energy in this particular case. This also explains why the solubility of salt, unlike that of AN, does not increase much with temperature. 4) Yes, there are numerous salts which undergo exothermic dissolution. In some instances they can raise the temperature enough to scald your hand. Some materials have such great hydration energy that they form stable hydrates like CaCl2:4H20 (calcium chloride). Some salts will get hot by hydration without dissolving. Calcium sulfate (plaster of Paris) is an example. If you need an exothermic salt for your project, you might consider anhydrous magnesium sulfate, which can be made by drying Epsom salts in a hot (400 deg F) oven in a disposable open pan which you can cover loosely when you turn the oven off to keep out moisture while the material cools. Once cool, you'll have to break up the solid fairly quickly and store it in a jar with a tight lid to protect it from moisture until you are ready for the demonstration. This dry salt will happily absorb water from the air (or your hands - wear gloves) until it is once again the original Epsom salts, MgSO4:7H2O. Do not use your Mom's good cookware for this project. The pan must be free of holes, because the salt is going to melt before it dries. Let a parent help you with the project, because they are going to be really mad if you spill hot, molten Epsom salts in the oven or worse, burn yourself. Jerry DOC0254 Subject: Re: CO2 in coke From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/19 Message-ID: <4galfm$b7o@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , wpenrose@interaccess.com (William R. Penrose) says: > >When you add ice, some CO2 bubbles are nucleated by irregularities on the ice >surface. (If you really want to demonstrate this, add a spoon of sugar or >salt to a glass of coke sometime.) Molecule-sized bubbles add more surface >area, so CO2 passes into them and they grow at a rapid rate. > Bill, I think on further consideration you might decide that "Molecule-sized" bubbles would not help much as nucleation sites, at least in the case of Coke fizz. Larger bubblets are more likely to get the job done. Jerry (Ico) < DOC0255 Subject: Re: Science Fair Cold Pack Salts From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/19 Message-ID: <4ganbv$b7o@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4g8d64$bcc@ixnews4.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: > >The change in free energy of a system equals the change in enthalpy >(sensible heat) minus the change in (absolute temperature times entropy >(disorder)). Ammonium nitrate marvelously disorders the equilibrium >structure of water. The energy for randomizing the water molecules from >their lowest energy interactions comes from the average molecular kinetic >energy of the system - the temperature drops. Energy is also absorbed by >the crystal forces in solid ammonium nitrate being broken as it goes into >solution. > Help me out here, Al. I thought the disruption of the crystal would be the dominating energy effect here - not the "randomizing" of the water. I guess my question is why an AN solution would be considered any more "random" than than any other salt solution. >Urea dissolved in water drops the temperature exceedingly well, too. > >>3) Why doesn't table salt make the water get colder? > >It doesn't disorder the structure of water. > Same question again. By what yardstick do we measure this lesser "disorder" other than by the circular reasoning that q/T is measurably less than in the case of AN? Being an old-fashioned guy (belated 19th century chemist), I have a lot of trouble dealing with the modern chemical paradigm. Your help will be appreciated. Al, your answer on this topic was directed to a seventh grade student who would be what, 12 years old? Don't you think maybe the reasoning was a little bit on the esoteric side for that age group? I hope you will be gentler with me if you decide to answer my query. You know I'm not so smart as I used to be before QM and GR taught us humility. Jerry (Ico) DOC0256 Subject: Re: Explosives -- academic research and career choices From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/21 Message-ID: <4gdvrg$n13@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , crobc@epix.net says: > > > >1. Are there academic (graduate) laboratories that conduct >legitimate and safety-oriented research in explosives, such that if >one were interested, they could do their M.S. or Ph.D. on this topic >? >Try New Mexico Tech's Energetic Materials Research and Testing Center at http://www.emrtc.nmt.edu/. Mel Cook used to head up explosives research at the U.of Utah, so you might check there, too. Unfortunately their web site isn't worth visiting. >2. Are the accident statistics for explosives researchers or >industrial explosives chemists much worse than those for chemists in >general ? > It depends. Most of the large manufacturers have very good safety records. However, I have too many very dead ex-acquaintances and ex-coworkers in the field. >3. Because I can imagine that it is possible to *really* counter >most of the hazards associated with this type of work by the use of >heavy sheilds and remote actuating equiptment (expensive, of >course), I wonder if these levels of precautions are actually used >or do people just put there hands right on their reaction vessels >and stir away. > It depends on what you are working with. I've blended a lot of high explosives in a kitchen mixer on a lab bench and manufactured class A explosives using ribbon mixers we rebuilt from food-processing equipment. On the other hand, for nitroglycerin we bought a very sophisticated Biazzi setup built over a swimming pool to dump the reaction mixture into if it got too hot. The plant had escape slides for the monitors and looked like a layman's concept of a modern stainless steel lab. Frequently, manufacturing facilities are barricaded, but often as not they are not. Lab blast shields are used extensively. One advantage in working with explosives is that you KNOW they are explosive. The nice thing about a simple shield is that you only lose a hand :) Jerry DOC0257 Subject: Re: [Q] Best way to keep fizz in drinks From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/22 Message-ID: <4gih9e$qp3@geraldo.cc.utexas.edu> Newsgroups: sci.physics,sci.chem In article <312c5c44.167246@news.dial.pipex.com>, mreeves@dial.pipex.com (Malcolm Reeves) says: > >Hi, > >Does anyone know the best way to keep the fizz in drinks, coke/pepsi, >lemonade etc. A program on the TV the other day stated that in was >best to compress the bottle to leave as little air space as possible >and then to screw on the cap. [snip] > But if you compress the bottle >won't it just expand, end result no gain? Anyone care to answer this >question ? > The program was right. Sure the bottle will gradually expand, but all during that expansion the net rate of CO2 loss to the gas space will be proportional to the difference between the activities of the dissolved CO2 and the free CO2. The instantaneous chemical activity of the dissolved material is independent of what's going on in the gas phase, but the activity of the gaseous CO2 is proportional to its concentration (pressure). THe CO2 concentration in the hullage space may initially be as low as near zero if it gets well ventilated when you take a swig. If you squeeze that air out, the partial pressure of the CO2 will rapidly rise to one atmosphere and an activity of unity when you screw the cap back on. If you leave a large hullage space after imbibing, that space may again be nearly pure air, in which case the liquid will have to give up enough CO2 to create 2 atmoshpheres total pressure in the now relatively large hullage before the activity (partial pressure) of the CO2 reaches unity (one atmosphere). The rate of loss of CO2 from the liquid in the squeezed bottle will be less than that in the unsqueezed bottle until such time as the partial pressures of CO2 in the two containers are equal. These approximations neglect the slight reduction in absolute pressure greated by the elasticity of the bottle. From a practical standpoint, the other two measures which help keep the fizz in the Coke are: 1) to to cool the beverage to the lowest possible non-freezing temperature before opening it and 2) to agitate the liquid as little as possible before opening it. It also helps if, before popping the lid, you slowly rotate the container end over end a couple of times, without sloshing, to allow the escape from the liquid of any entrained nucleating bubblets which may have formed when your mate tossed the bottle to you:) Jerry (Ico) DOC0258 Subject: Re: Does Heat Speed Up or Slow Down a Chem From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/23 Message-ID: <4glh2j$83q@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4gk4p4$8b8@mserv1.dl.ac.uk>, ijb@mserv1.dl.ac.uk (I.J. Bush) says: > > >Heating up a system will always increase the speed at which equilibrium >is reached. Why ? Can you not think of a scenario or three in which equilibrium is attained more slowly at higher temperatures? Consider heterogeneous systems in which phases play a role in determining reaction rate. Jerry (Ico) DOC0259 Subject: Re: Minority Postdoctoral Fellowship Opportunity From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/23 Message-ID: <4gj7co$g3f@geraldo.cc.utexas.edu> Newsgroups: sci.chem.organomet,sci.chem In article <4gg8ob$2mb@mailhost.zeneca.co.uk>, Geoffrey Cooper says: > >Dear Rob, > If you waste your time responding to "Uncle" Al's blatherings, >remember the saying "I refuse to have a battle of wits with an unarmed >man". Al is a flaming moron, apparently with endless time on his hands. > I would like to see this group become moderated to restrict it to >chemistry issues. This would keep the "Uncle" Als to a minimum. > Well, Geoffrey, if they ever do decide to make this a moderated group, how do you know that Uncle Al will let you post? The following list is of short quotes abstracted from your other four postings to the sci.chem group this month: The comments about slimeball behavior should rightly be addressed to Mr. Lloyd Parker this time. Tom's slimeball behavior was addressed in my earlier post. Birds of a feather! Maybe you all would like to move out of America, One wonders if you have a life, or if you spend your time in the sort of mental masturbation that seems to characterize your all-too-abundant postings. Maybe you're John Doe #2 from OK city! It sure seems to fit Irrational hatred of the bogeyman government, affinity for terrorism when it fits your bill, apparent association with cult groups. Yes, please! Let's hear some organic chem instead of the political nuts ranting and raving. It appears that Uncle Al is just one of a number of people whom you don't like very much. Do you also do chemistry or only ad hominem social, psychological and political commentary? Jerry (Ico) DOC0260 Subject: Re: Minority Postdoctoral Fellowship Opportunity From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/23 Message-ID: <4gk498$3gu@geraldo.cc.utexas.edu> Newsgroups: sci.chem.organomet,sci.chem In article <312D3D92.4A29@ix.netcom.com>, Geoff Cooper says: > >Gerald, You're right. Yes, I am. [Irrelevant personal opinions of Uncle Al's political opinions snipped] >But what matter that to someone like you who already has all the >answers? I'm disappointed. That teensy bit of temper barely deserves the following update of quotable ad hominem quotes. Oh well, at least you are seven for six in posts containing SOME ad hominem remarks unadulterated by any chemistry. Here they are in poor chronological order: Tom's slimeball behavior was addressed in my earlier post. Birds of a feather! Maybe you all would like to move out of America, [Indirect reference] The comments about slimeball behavior should rightly be addressed to Mr. Lloyd Parker this time. One wonders if you have a life, or if you spend your time in the sort of mental masturbation that seems to characterize your all-too-abundant postings. Maybe you're John Doe #2 from OK city! It sure seems to fit Irrational hatred of the bogeyman government, affinity for terrorism when it fits your bill, apparent association with cult groups. Yes, please! Let's hear some organic chem instead of the political nuts ranting and raving. Al is a flaming moron, apparently with endless time on his hands. But what matter that to someone like you who already has all the answers? We know it is tough being a college student or tyro working scientist and not having the time to play with the big boys, but in two or three decades, who knows? Maybe you'll be a second Uncle Al and a master of sarcasm as well. By the way, your comment that "unreliable science is useless science." needs a little rethinking. That is a layman's concept of perfectly structured "science" which is built on such a firm foundation that its paradigms lead unerringly upwards. It is precisely the "unreliable" areas of science that are most exciting and it is in the closer examination of the things that seem to bend the rules that we will find the next theory or invention. "Reliable science" is what we better call "engineering." Jerry Troll, troll, troll your gloat slyly down the scheme, Verily, verily, warily, warily, things aren't what they seem.- Ico < DOC0261 Subject: Re: Copper/Cupric Oxide Question From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/24 Message-ID: <4go28c$qv0@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4gm3cp$dp7@cobain.rowan.edu>, kilroy@copland.rowan.edu (Dr Nancy's Sweetie) says: > >"Bright copper kettles". Shouldn't these also form >a layer of cupric oxide, and shouldn't that also be toxic? It seems odd >to make food preparation containers out of a material which supposedly >forms toxins. It seems extra-odd that people don't get sick after eating >food cooked in such pots. > I should have added in my prior response that a little copper can sometimes be beneficial in cooking. Lined copper (tin) is the preferred cookware of great chefs unless they can afford silver. These metals have high thermal conductance which assures uniform heating across the cooking surface. There are cases where untreated copper is used in food preparation. Egg whites beaten in a copper bowl, for instance, produce a superior meringue. Jerry (Ico) DOC0262 Subject: Re: Copper/Cupric Oxide Question From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/24 Message-ID: <4go1m9$qv0@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4gm3cp$dp7@cobain.rowan.edu>, kilroy@copland.rowan.edu (Dr Nancy's Sweetie) says: > >But today, my wife happened to be singing "My Favorite Things" from >`The Sound of Music'. In particular, the first stanza got my attention, >because it mentions "Bright copper kettles". Shouldn't these also form >a layer of cupric oxide, and shouldn't that also be toxic? It seems odd >to make food preparation containers out of a material which supposedly >forms toxins. It seems extra-odd that people don't get sick after eating >food cooked in such pots. > DOC0263 Subject: Re: Does Heat Speed Up or Slow Down a Chem From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/24 Message-ID: <4gmeon$t6i@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4gldu2$cot@lll-winken.llnl.gov>, shaw@s119.es.llnl.gov (Henry Shaw 510 423-4645) says: > >In article 6jn@reader2.ix.netcom.com, Alan \"Uncle Al\" Schwartz () writes: >> Heat may speed up a reaction, slow it down, or have no effect upon it at >> all. It depends upon the thermodynamics of the reaction. > > > The equilibrium state may change as a function of temperature, but >heat will *always* speed up the rate of a fundamental reaction. > What is a "fundamental" reaction? If an overall reaction slows with increasing temperature does that automatically qualify it as "non-fundamental"? >> >> In general, hotter means faster, doubling reaction rates near room temp >> for every 10 celsius rise in temperature. > > >You can't make a general statement like this. The heck you can't. Competent chemists have been using this approximation as a first estimate for thought experiments for a long time. The fact that the statement doesn't qualify as a fundamental law does not mean that it has no utility - especially for explaining the typical behaviour of simple homogeneous reactions and a lot of heterogeneous phenomena. Jerry (Ico) DOC0264 Subject: Re: [Q] Boiling water at low pressure From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/24 Message-ID: <4gmf2g$t6i@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <312E9040.7E3B@indiana.edu>, "John C. Huffman" says: > >The answer is in your cookbook. When cooking at high elevations, most >often there are instructions to add salt--this is NOT for flavor, but to >raise the boiling point. It is indeed the temperature that cooks the egg. >Calculate the boiling point at 29,000 ft and then figure how much salt >would be necessary to raise the temperature accordingly. >-- Yuck. Who would add 50 grams of salt to a liter of water to raise the BP by half a degree C?? It would be easier to lug a pressure cooker to the top of Mt Everest than enough salt to do much cooking. Jerry (Ico) DOC0265 Subject: Re: [Q] Boiling water at low pressure From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/24 Message-ID: <4go7te$23c@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4go647$qv0@geraldo.cc.utexas.edu>, glhurst@onr.com (Gerald L. Hurst) says: > >Notwithstanding the rhetoric, the practical use of salt to raise >the boiling temperature of water for cooking purposes at 29,000 >feet is a joke. Saturated NaCl is about 6.5 molar so the increase >in boiling point would be about 3 deg C. At the top of Mt Everest Pardon me, I forgot to count my ions. The maximum increase in boiling temperature should be roughly 7 degrees, not 3 degrees for saturated salt water - raising the boiling point on Everest to the high 70's. Still can't brew a decent cup of tea at that altitude even if you don't mind a little salt :) Jerry (Ico) DOC0266 Subject: Re: [Q] Boiling water at low pressure From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/24 Message-ID: <4go647$qv0@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <312F19EE.3377@indiana.edu>, "John C. Huffman" says: > >Gerald L. Hurst wrote: >> >> In article <312E9040.7E3B@indiana.edu>, "John C. Huffman" says: >> > >> >The answer is in your cookbook. When cooking at high elevations, most[snip] >> >-- >> Yuck. Who would add 50 grams of salt to a liter of water to >> raise the BP by half a degree C?? It would be easier to lug >> a pressure cooker to the top of Mt Everest than enough salt >> to do much cooking. >> >> Jerry (Ico) > >How fast does salt diffuse through an egg-shell? Shucks, I always salt >my hard boiled eggs anyhow. And don't forget, the question was " asked >us if it was possible to hard-boil an egg on top of Mt. Everst" He >didn't say anything about eathing it :-) You go ahead and carry your >pressure cooker. Notwithstanding the rhetoric, the practical use of salt to raise the boiling temperature of water for cooking purposes at 29,000 feet is a joke. Saturated NaCl is about 6.5 molar so the increase in boiling point would be about 3 deg C. At the top of Mt Everest the boiling point of water would be around 70 deg C so those three degrees would hardly do the trick, would they? So instead, you decide to use a more soluble salt and finally succeed in raising the temperature of your fused mixture to 100 degrees. Ooops, the egg cracked and exploded because of the differential pressure across that salt-proof shell (about 10 psi at 29,000 ft) and you, Dr. H, wound up with egg on your face :) Jerry (Ico) DOC0267 Subject: Re: Does Heat Speed Up or Slow Down a Chem From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/25 Message-ID: <4goq52$ch1@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4gok49$9le@pulp.ucs.ualberta.ca>, ssia@pop.srv.ualberta.ca (Sam Sia) says: > >In article <4glh2j$83q@geraldo.cc.utexas.edu>, glhurst@onr.com says... >> >>In article <4gk4p4$8b8@mserv1.dl.ac.uk>, ijb@mserv1.dl.ac.uk (I.J. Bush) >says: >>> >>> >>>Heating up a system will always increase the speed at which equilibrium >>>is reached. Why ? >> >>Can you not think of a scenario or three in which equilibrium >>is attained more slowly at higher temperatures? Consider >>heterogeneous systems in which phases play a role in determining >>reaction rate. >> >>Jerry (Ico) > >So are you saying the Arrhenius equation is false? > Not unless I'm speaking sotto voce and and am going deaf. Take the hypothetical reaction: FP + O2 + xH20 --(NaCl)-> Fe2O3:xH2O This reaction can be observed to accelerate greatly as a result of a temperature drop of only 20-30 deg C. The increase in rate as measured by the amount of Fe2O3 produced per year apparently arises from phase changes taking place in one of the reactants, and that phase change more than offsets any accompanying modest drop in temperature. Actually it is not just Ford pickups that rust more quickly in the cold high RH environment of the northeastern US. Out in the southwestern states where the absolute humidity may be just as high or higher and salt and alkali are often abundant, those same vehicles may be virtually rust free. The point is that the Arrhenius equations describing a reaction may have to be rewritten if one of the reactants acts as more than merely a species which can be fully characterized by a concentration figure. Of course, if you have an unlimited supply of Arrhenius equation parameters at hand, you can calculate most anything to within the limits of (delta t)(delta E). Some reaction rates may seem to depend on the mood of the Maxwell demon who is opening and shutting the little door between the reactants. Under such circumstances I recommend the use of Ico's famous fudge factors for the normalization of intractable yellow gunk. BTW, for the sake of consistency the term "rate" as used herein refers the the instantaneous value of dPR/dt where t is time and PR is the magnitude of the pile of rust. Jerry (Ico) DOC0268 Subject: Re: [Q] Boiling water at low pressure From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/25 Message-ID: <4gor2j$fm5@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4gomti$cg4@news.aladdin.co.uk>, tonywilk@aladdin.co.uk (tonywilk) says: > >"Michael R. Jones" wrote: > >*snip* >>...hard-boil an egg on top of Mt. Everst [el. 29 029 ft]. >*snip* > >Hmm... seems like a chance to look at it sideways.... > >The question doesn't _specifically_ state you have to boil it >in water does it? >Why not just boil it in something who's boiling point will be >around 100C at that altitude ? > >Preferably something non-toxic :-) > >Would Glycerine (or a mix with water) do the trick ? It would if you don't mind a face full of hot glycerine when the occassional egg blows up. With a little bit of luck you may avoid this if the shell is undamaged, thanks to the good structural engineering of the shell. But don't bet on it. I understand they used to boil a lot of rotten eggs in oil. Jerry < DOC0269 Subject: Re: Does Heat Speed Up or Slow Down a Chem From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/26 Message-ID: <4gt4od$eis@geraldo.cc.utexas.edu> Article Segment 2 of 2 Now let's assume that A is a catalyst for reaction 2 and C is a catalyst for reaction 3. Also assume that the equilibrium in reaction 1 is strongly influenced by temperature. If you have a mixture of A,B,D and F, can you unequivocally say that both reactions 2 and 3 will accelerate with temperature? Jerry (Ico) DOC0270 Subject: Re: Does Heat Speed Up or Slow Down a Chem From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/26 Message-ID: <4gt4od$eis@geraldo.cc.utexas.edu> Newsgroups: sci.chem Article Segment 1 of 2 In article <4gsk22$nvl@larry.cc.emory.edu>, lparker@larry.cc.emory.edu (Lloyd R. Parker) says: > >: Take the hypothetical reaction: > >: FP + O2 + xH20 --(NaCl)-> Fe2O3:xH2O > >: This reaction can be observed to accelerate greatly as a result >: of a temperature drop of only 20-30 deg C. The increase in rate >: as measured by the amount of Fe2O3 produced per year apparently >: arises from phase changes taking place in one of the reactants, >: and that phase change more than offsets any accompanying modest >: drop in temperature. > >Huh? Could it be that salt is only used when it is cold? Sorry, this is >NOT an example of lower temperatures causing a faster reaction. If you >place the same truck with the same amount of water and salt at high >temperatures, and keep the salt in contact with the metal just as long, >the rusting will go faster. (Frozen salty slush stays in contact with >the metal longer than salt water.) > >: Actually it is not just Ford pickups that rust more quickly >: in the cold high RH environment of the northeastern US. Out >: in the southwestern states where the absolute humidity may be >: just as high or higher and salt and alkali are often abundant, >: those same vehicles may be virtually rust free. > >Keep the salt and water in contact with the metal as long and compare. >And I've seem rusty cars in coastal areas quite a lot. > >If you were being facetious, I apologize, but it seems you're serious. I an quite serious. Of course they add salt (CaCl2) to roads in some areas, but that has nothing to do with this discussion. Hold the ambient salt and absolute humidity constant but lower the temperature, and in certain instances the rate of rusting will increase, not decrease. What reason is there to doubt this statement other than mere adherence to the dogma that "all reactions increase in velocity with temperature." Is it not generally true that various corrosion and other degradation reactions occur more slowly in Egypt than in Ireland, and is it not true that this difference is at least partly attributable to the difference in relative humidity? RH is an inverse function of temperature at constant AH (absolute humidity, water vapor concentration) is it not? Does it not therefore follow that we should expect some reactions to increase in rate if a fall in temperature produces higher RH. Imagine that you work in an un-air-conditioned labortory in, say, Dallas and one of your jobs is to grind samples of ammonium nitrate into a fine powder. All of the surfaces in that lab become coated with a fine lawer of AN dust, but the metallic surfaces remain bright an shiny all day long. When you return to the lab the following morning the metalwork is uniformally covered with a patina of orange rust. You polish all the metal back to its original sheen and once again it stays bright all day. Next morning it's all rust again. Remember, this is Dallas, not Hell - although some might argue about the distinction in summer. Your problem is simple. The humidity (AH) is pretty much constant but the RH is cycling a little above and a little below about 60% - above during the day and below during the night. Ammonium nitrate has the inconvenient property of being deliquescent below about 60% RH and so each night the salt liquifies and acts as a corrosion accelerator. The next morning it recrystallizes as the temperature rises and the rusting slows to a crawl. I chose a reaction in which one can actually see the surface change which affects the reaction rate in the opposite direction from that expected for the temperature change. However any heterogeneous reaction may involve surface phenomena which are not visible, but which have a profound effect on overall reaction kinetics. Let's look at a generalized reaction scheme - this time without regard to whether the reaction mixture is homogeneous or heterogeneous: 1) A + B<--->C k = f(T) 2) D-->E 3) F-->G DOC0271 Subject: Re: Does Heat Speed Up or Slow Down a Chem From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/27 Message-ID: <4gu3tk$bea@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4gtft4$e58@lll-winken.llnl.gov>, shaw@s119.es.llnl.gov (Henry Shaw 510 423-4645) says: > >> >In article 6jn@reader2.ix.netcom.com, Alan \"Uncle Al\" Schwartz () writes: >> >> Heat may speed up a reaction, slow it down, or have no effect upon it at >> >> all. It depends upon the thermodynamics of the reaction. >> >> In general, hotter means faster, doubling reaction rates near room temp >> >> for every 10 celsius rise in temperature. >You can't make a general statement like this. [My disagreement snipped] >I didn't say it had no utility, but unless the person using this >rule of thumb is also aware of its limitations, it could lead someone >astray. For instance take these two simple bimolecular gas reactions: > Pardon the snipping of the previous messages to the original and your last. I am merely making the point, in the first quoted paragraph, that the original poster (Uncle Al) qualified his use of the "reaction rate doubles (or triples) for every 10 degrees" phrase adequately. No chemist is going to seriously try to tell anyone that all reactions follow this rule any more than one would suggest that arthritis is a good weather indicator. My prior arguments were devoted to the idea that increasing temperature may even decrease the rate of an overall reaction so I hardly need to be told that the rule of thumb is not a substitute for the science of chemical kinetics. I think we can all rest assured that Al knew the limitations of the rule at the time he published it and that he chose not to elaborate beyond saying, in effect, that it might not work at all or might even work backwards. The only disagreement you ran into was my statement that one may indeed quote the old saw if one wishes to and that a very great number of outstanding chemists have done so with as much or as little qualification as they thought appropriate under the circumstances. Jerry (Ico) DOC0272 Subject: Re: Does Heat Speed Up or Slow Down a Chem From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/28 Message-ID: <4h0fan$mv0@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4gv5um$dde@curly.cc.emory.edu>, lparker@curly.cc.emory.edu (Lloyd R. Parker) says: > >Sorry, but you're varying the amount of a reactant, or at least a >catalyst. That's what affects the rate of your reaction. Keep RH >constant and let the temperature vary and see what happens. You should be sorry. If you keep the RH steady and vary the temperature then it is YOU who is varying the amount of one of the reactants. It is the AH not the RH which must be held constant if you wish to maintain a constant amount of water. More accurately, we should let the total water present remain constant at the expense of a microscopic drop the AH, But you know how difficult it is for me to split hairs. >: Let's look at a generalized reaction scheme - this time without >: regard to whether the reaction mixture is homogeneous or >: heterogeneous: > >: 1) A + B<--->C k = f(T) > >: 2) D-->E > >: 3) F-->G > >: Now let's assume that A is a catalyst for reaction 2 and C is >: a catalyst for reaction 3. Also assume that the equilibrium in >: reaction 1 is strongly influenced by temperature. > >But (1) is a fast step and builds up a constant amount of C. As soon as >some is used by (3), the equilibrium in (1) shifts to make more. If you like, (1) can be a fast step, but since C is a catalyst, it does not get used up. Furthermore, we have already stipulated that the equilibrium constant for (1) does indeed vary sharply with temperature, so under the variable conditions we are are interested in here, C is most definitely not constant, but also not "used up." > >: If you have a mixture of A,B,D and F, can you unequivocally say >: that both reactions 2 and 3 will accelerate with temperature? > >Unless you can prove by an actual example that the Arrhenius equation >fails, yes. A higher temperature leads to more energetic collisions, so >more collisions have sufficient energy to overcome the activation energy >barrier. > The Arrhenius equation has absolutely nothing to do with this thought experiment and it does not have to be held "incorrect" to to make the premise true that: Either reaction 2 or reaction 3 MAY (or may not) slow down with increasing temperatures as measured by the decrease in the rate of production of either E or G respectively or by the decrease in rate of loss of either D or F respectively. It is not always necessary to break a law to get an unexpected result. We are not here trying even for a loophole, but merely pointing out that the fact of raising a closed system's reaction temperature is not a guarantee that a given specified net reaction will proceed more rapidly. Some may prefer to shrug and say that "this doesn't count" because some "fundamental" reaction behind the scenes is always obeying Arrhenius' law, but that does not alter the fact of our observation of the end result, which outside of academe, may sometimes be equivalent to "the bottom line." One little added thought: If B in (1) is nothing, then A = C, but they are the same species in the same total amount, differing only in phase. Phase transitions are notoriously temperature dependent as is exemplified by water in the 99 - 101 deg C range. Other phase changes may be just a sharp, but less obvious. Thus the admonition to be especially wary of the kinetics of any reaction involving such sometimes subtle transitions. >: Jerry (Ico) DOC0273 Subject: Re: How to melt magnesium ? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/28 Message-ID: <4h0qi7$aqb@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.engr.chem,sci.engr.metallurgy,rec.crafts.metalworking In article <4gul4a$egr@news.knoware.nl>, Klaas van Ditzhuyzen says: > >I want to try melting magnesium. >I don't have exotic equipment like a vacuum furnace or a professional >lab, but just a simple workshop with a propane torch. >But an attempt to melt Mg on the air will ignite it. >So I thought about melting under a salt-bath. Then the salt mixture >should have a low s.g. (less than liquid Mg == 1.6) and a melting >point under 600 deg C. An NaCl / KCl mixture is too heavy and the >Mg will float on it. >Does somebody know such salts (or other ideas to melt Mg in an >ordinary garage) ? > No problem. Put the magnesium in a suitable crucible, turn the crucible upside down in second, larger crucible containing the salt of your choice and then melt the latter. The magnesium, when it melts by contact with the hot liquid salt, will float happily on that denser, molten material, fully protected from the air. If the salt won't float on magnesium, then magnesium will float on the salt. Jerry (Ico) DOC0274 Subject: Re: What is the temprature at which paper burns? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/29 Message-ID: <4h2rmn$ioo@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.engr.chem In article <3133F803.41C6@iil.intel.com>, "Opher D. Kahn" says: > >If you know, please tell! > Ignition temperatures in general are hard to pin down and are usually expressed as a relatively broad range. Paper, wood and the like are particularly difficult to quantify because the ignition temperature often depends greatly on their history as well as on their specific composition. If a piece of wood is left in contact with a lightbulb for a period of weeks or months, it may eventually become so active that it bursts into flame when the surface that was adjacent to the bulb comes into contact with air. In the old days, when chemistry was more of a hands-on science, many students learned about pyrophoric versions of materials which are normally considered stable with respect to combustion or at least spontaneous combustion. I am here referring to such materials as iron and lead. Even the simplest of substances, such as hydrogen gas, may exhibit unpredictable behaviour with respect to ignition temperatures depending on its environment and the recent history of that environment insofar as invisible sometime transitory surface effects may be present. Jerry (Ico) DOC0275 Subject: Re: liquid heavier than water? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/02/29 Message-ID: <4h356a$vl@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4h2kb8$n7a@ixnews2.ix.netcom.com>, oldetyme@ix.netcom.com(BILL CARMICHAEL ) says: > >I am looking for a non-flammable liquid that is or could be dyed blue >that is heavier than water.It cannot mix with the water as the water >must float on top of it. We are wanting to use it in water globes for a >two tone effect. Any ideas? One of the phthalate esters might do the trick. Dibutyl phthalate is a little denser than water, has low toxicity and should take a number of dyes nicely. The other lower phthalate esters are even denser but perhaps not quite as benign or as readily available. Possibly even a short-chain fatty acid might work, but I think I'd go with the phthalates. Jerry (Ico) DOC0276 Subject: Re: non exothermic From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/01 Message-ID: <4h5jjr$gvs@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <9602291926.0RAUI00@cornucopia.digital.net>, cathy.hettinger@cornucopia.digital.net says: > > >I realize I am being awful simplistic here. But, I realize you are generally >talking about endothermic reactions. Could you tell us what posts you are responding to? Jerry (Ico) DOC0277 Subject: Re: How to melt magnesium ? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/02 Message-ID: <4h97pu$b0i@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.engr.chem,sci.engr.metallurgy,rec.crafts.metalworking In article <1996Mar1.144251.21352@roper.uwyo.edu>, jimkirk@uwyo.edu (James Kirkpatrick) says: > >In article <31358ed8.213163@news.northernnet.com>, dwilkins@northernnet.com (Don Wilkins) writes: >|>... The magnesium is indeed oxidized when it reacts with >|>nitrogen. > >Please explain the reaction. If you have elemental magnesium, and >elemental nitrogen, how on earth can you get an oxidation reaction >without oxygen!!?? > 3Mg + N2 --> Mg3N2 Not so stable as MgO, but holds together up to 800K. Jerry (Ico) DOC0278 Subject: Re: [Q] Boiling water at low pressure From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/02 Message-ID: <4haiia$1nl@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4hagkf$hou@news.aladdin.co.uk>, tonywilk@aladdin.co.uk (tonywilk) says: > >"Michael R. Jones" wrote: > >> As the origional poster, I would like to thank all of you for helping >>me. My mail server is ill, so if you mailed me and I haven't responded, >>my mail server is messed-up. >*snip* >> ... if a pressure cooker can't be found, that one use a >>different substance to boil. I will suggest mercury or oil. >*snip* > >Practically I wouldn't suggest mercury for 3 reasons: > > 1. it would be _very_ heavy to carry > 2. it is toxic > 3. It would be almost impossible to force an egg under > the surface of a container full of mercury without > breaking the egg. > Because of the density of Hg is so high, even > metal coins will float on the surface. > >I would stick to using a light oil (e.g. cooking oil) > What measures will you take to prevent the egg from exploding if you heat it in oil above the ambient boiling temperature of water at the top of the mountain? I am wondering if you and the original poster, having read all the postings on this topic, have learned or know something that I missed. Jerry (Ico) DOC0279 Subject: Re: What is Baume? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/03 Message-ID: <4hbdab$oqo@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4hb7s0$taq@news.netam.net>, pletcgm@netam.net (G. Michael Pletcher) says: > >I have muratic acid that contains 20% HCL and 32% Baume. What is >Baume? > Degrees Baume is a measure of specific gravity originally based on assigning 10% NaCl solution a value of 10. In the USA the relationship at 60/60 degF is usually expressed: sp.gr. = 145/(145-Baume) In the present case there is something wrong because 20% HCl is nowhere near 32 Baume. What you probably have is 32% HCl, which corresponds to about 20 degrees Baume. Be aware that there are a bunch of other methods for reaching values for Baume so your milage may vary a little in Washington DC, Amsterdam and Germany. Jerry (Ico) DOC0280 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/07 Message-ID: <4hnine$nab@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.energy,sci.mech.fluids,sci.materials,sci.physics In article , jmc@Steam.stanford.edu (John McCarthy) says: > >Let me return to the topic of the thread - energy of atoms in >molecules. > >I'm not entirely sure of this, so I hope someone will correctly if I >am mistaken. > >Molecules have ground states and can absorb energy to go into excited >states. However, until a temperature considerably higher than room >temperature is reached, molecules are almost all in the ground state. >Hence the internal energy of molecules does not contribute to the >specific heat of the substance below relatively high temperatures. > >Someone should tell us how high. >-- If you track the heat capacity of a simple gas such as hydrogen as a function of temperature from well below room temperature up to say a theoretically extrapolated temperature of say 6,000 deg, you will find that there is a continuousincrease in the value. In my simple way, I assume that the major low-temperature contributions to the value are first from rotational states as is consistent with the relatively low frequency of infrared rotational spectra. More complex molecules show much higher heat capacities than simple diatomic molecules below room temperature, so at least a number their more numerous degrees of freedom must be active. For instance, C(v) for ethanol is nearly 5 times greater than for a monatomic gas at room T. Presumably, the larger molecules have an easier time of it in reaching numerous vibrational states because they do not necessarily require intermolecular collisions to enable a new mode. Anyhoo, it does appear that internal modes of one sort or another are significantly active at normal temperatures albeit nowhere near as active as at higher temps. One incidental point is that at high pressure or low temperature one may sometimes see increases in heat capacity on cooling, even in the case of hydrogen or inert gases. At the other extreme, even monatomic gasses may show increases in C(v) as a result, I assume, of ionization. Jerry (Ico) DOC0281 Subject: Re: How did he die? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/09 Message-ID: <4hssjg$fnc@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4hsbct$ove@dfw-ixnews2.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: > >glhurst@onr.com (Gerald L. Hurst) wrote: >>A man is found dead and badly burned in a fire. The autopsy shows >>that although the man was a smoker, his lungs are bright red, >>but there is a little soot in his mouth. The DA alleges that >>he was murdered by someone pouring gasoline on him and igniting >>it in the burned house. Was he killed by the fire? > >Carbon monoxide (or hydrogen cyanide) would fill the bill. >Dr. Kevorkian did it. > >If carboxyhemoglobin or cyanide (or its metabolite thiocyanate) are not >found, the man was killed while well-oxygenated - homicide. Let's stipulate that the CO saturation of the blood was only 10 percent. If it was murder, was it the fire that killed him? How about natural causes with a cigaret or lighted match in his hand? Jerry (Jerry) DOC0282 Subject: Re: Mineral Spirits of Kerosene From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/09 Message-ID: <4hssrc$fnc@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4hsb79$ove@dfw-ixnews2.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: > >glhurst@onr.com (Gerald L. Hurst) wrote: >>You are told only that they found some material that the >>laboratory analyst said was "mineral spirits of kerosene" >>at the scene. Later various people ask you as a chemist to >>tell them just what it was that was found. What do you say, >>and on what do you base your opinion? > >Unless you can find an industrial or literature reference to "mineral >spirits of kerosene" you say nothing. Professional pronouncements ex >cathedra carry the weight of personal liability. NEVER defend another >person's work with your opinions unless you wish to tightly grasp the >tar baby. > That's fair enough, but now let's ask if anyone amongst us chemists has actually seen an industrial reference to "mineral spirits of kerosene" or if it is otherwise perhaps a phrase invented by the analyst. Jerry (Ico) DOC0283 Subject: Re: supersaturation problems -- help us!! From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/11 Message-ID: <4i2a61$rnb@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4i1vui$5o7@service2.uky.edu>, rtore00@pop.uky.edu (Rob Toreki) says: > >In article >ekrause@sisnet.ssku.k12.ca.us (Elizabeth Krause) writes: > >> Hi! This is Elizabeth Krause and lab partner Mandi McDowell and we have >> some questions. While doing a experiment on supersaturation we followed a >> "recipe" in a high school chemistry book. This book said that 46.5 g of >> Sodium Acetate would dissolve completely at 20 degrees C in 100 ml. [Snip] > >The Merck Index (a sci.chem standby) says 1 g of sodium acetate >dissolves in 0.8 ml room temperature water and 0.6 ml boiling water, so >it appears your "recipe" may indeed be your problem. Using these >numbers, you aren't saturated after cooling your 83 g from 50 degrees >unless you started with 66 ml or less of water! > Professor, you may not be referring to the material used by these young folks in their experiment. The solubilities you quoted are those of the trihydrate. Perhaps they are using the anhydrous material. Jerry (Ico) DOC0284 Subject: Re: Help with solubilities / mixed salts From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/13 Message-ID: <4i5ltu$l5k@geraldo.cc.utexas.edu> Newsgroups: sci.chem,alt.engr.explosives Article Segment 1 of 2 In article <4i2iqv$kvq@news.aladdin.co.uk>, tonywilk@aladdin.co.uk (tonywilk) says: In article <4i2iqv$kvq@news.aladdin.co.uk>, tonywilk@aladdin.co.uk (tonywilk) says: > >Quick background: >---------------- >After an experiment to convert KCl to KClO4 by electrolysis >I recovered 36g of solid, which due to starting materials >and concentrations I am assuming contains a mixture of: > KClO3 > KClO4 (OK, it might be a BIG assumption!) > >Attempting to simply determine the composition of this I >Took 30g of the solid and dissolved in 405ml water. > >My assumption being: > If the whole was KClO3 (solubility 7.4g/100ml @ 20C) > then 30g would all be in a saturated solution at 20C > in 405ml of water. > If it were all KClO4 (sol. 1.8g/100ml @ 20C) then > I would have 7.3g in solution and 22.7g solid. > >I decided on 20C since it's easy to stabilise at that >temp. and the solubility curve aint so steep lower down. > >Warmed the solution to 22C, shook it up a lot, then left >it for 3 hours with occasional shaking. This actually >kept it at 20C as the ambient was 19-ish and holding >the flask to shake it added a degree. > >Filtered at the pump...dried the solid = 17.1g >So... there's 12.9g left in 405ml of solution. > > >Here's the Questions: >-------------------- >Firstly: If I have solubility data for both KClO3 and KClO4 >can I directly calculate the proportion of these 2 salts ? > >If (as I suspect) not... is there a general rule which >allows calculation of the solubilities of 2 salts in solution? > >I currently can't understand how to draw up a phase diagram >showing the mutual solubility of two salts, although in trying >to replicate a diagram for KCl/NaCl (from Perry's) I'm led >to believe that the Cl in common has a lot to do with the >reduction in solubility of one salt as the other is increased. > >Any help gratefully accepted, > >Yours, > > Tony Wilk > >P.S. If poss. please include ISBN's for any book refs - > saves hours in the library - ta. > If the composition is made up of ONLY the two compounds you expect, it would have to be mostly the perchlorate such that there is a healthy excess along with enough chlorate to make up the weight total to 12.9 g in what is something over 405 ml, lets say V. For what they are worth we can use estimated solubility constants to guess at the equilibrium of the saturated KClO4 [K][ClO4] = M1^2 where M1 is the estimated molarity of pure saturated KClO4 and its square is the estimated value of the soly constant [ClO4]*FW1 + [ClO3]*FW2 = 12.9*V/1000 where FW1 and FW2 are the formula wts of the two pure potassium salts. [ClO4] + [ClO3] = [K] The positive and negative ion molarities must add up. This gives you three equations in three unknowns so you can solve for the three unknowns and, at least in theory, determine the amounts of the two salts making up your 12.9 grams of dissolved material. Note that there cannot be any chlorate left in the solid because if there were, the mix would keep dissolving past the 30 g total mark even if saturated with KClO4. You can check this assertion by using: [K][ClO3] = M2^2 (M2 = molarity of saturated pure KClO3) along with the analogous KClO4 equation above to show that for a saturated solution of both salts: [K]^2 = M1^2 + M2^2 Which allows you to plug the calculated [K] back into the two solubility constant equations of the two pure compounds to get the concentration of each material in a hypothetical saturated solution, if you also remember that the positive and negative ions again will add up. Keep in mind that we are here working with ideal concepts and trying to apply the common ion priciple to pretty strong solutions. Also, the already limited accuracy is totally dependent on your compositioon being made of what you think it is. DOC0285 Subject: Re: Help with solubilities / mixed salts From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/13 Message-ID: <4i5ltu$l5k@geraldo.cc.utexas.edu> Article Segment 2 of 2 You need to begin by converting your solubilities into estimated molarities. I say estimated because dissolving x grams of a salt in 100 ml of water will give you 100+(x-?) mililiters total solution. Here's a hint on density estimates for KClO3: 1.011 @ 2%, 1.024 @ 4%. Extrapolation and estimation of similar values for the perchlorate are plenty good enough for this rough work. Jerry (Ico) DOC0286 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/13 Message-ID: <4i66ba$1af@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.energy,sci.mech.fluids,sci.materials,sci.physics In article <4i0409$m1k@agate.berkeley.edu>, ted@physics12.Berkeley.EDU (Emory F. Bunn) says: > >You seem to be claiming -- again, please correct me if I'm >misinterpreting you -- that your definition is the one used >historically by Gibbs, Boltzmann, and that crowd. If that's true, >then I'm grossly misremembering what I've read about the history of >thermodynamics. That's possible; I'll have to go read up on the >subject again some time. > Perhaps it would help to clarify my viewpoint if I post my personal favorite definition of temperature: The characteristic property of the scale which I now propose is that all degrees have the same value; that is, that a unit of heat descending from a body A at the temperature T of this scale, to a body B at the temperature (T-1), would give out the same mechanical effect, whatever be the number of T. This may justly be termed an absolute scale, since its characteristic is quite independent of the physical properties of of any specific substance. -William Thompson, "On the Absolute Thermometric Scale founded on Carnot's Theory of the Motive Power of Heat and calculated from Regnault's observations," Phil. Mag. (3) 33, 313 (1848). If I may add a note. Thompson had worked with Regnault the prceding year and the latter had just published a book. Regnault had done a lot of work on gases including building an outstanding air thermometer. At the time the above quote was written, Thompson also mentioned and gave credit to Joule, who had earlier developed the now classic and simple kinetic theory of gases based on his concept of molecules which was not widely accepted at that time. Despite his experience with Regnault, Thompson at this time didn't really believe that an "ideal gas" thermometer would track well with his new scale, probably because the one he built with his assistant did not. It was 3 years later when he did an about face and recognized the ideal gas scale as being the same as his thermodynamic scale. I personally suspect that his original doubts were based on Regnault's work. Despite the fact that R had built a decent gas thermometer, much of his work had concentrated on showing the variations of real gases from the idealizations of Charles and Boyle. Thompson may have at first been more aware of how bad it could get rather than how good, merely becaue of the object of the work :) Just as Thompson based his work on the Carnot cycle, so did Gibb's concept of entropy spring from the same source, independently but at roughly the same time. Entropy descended readily from the Carnot reduction: Q1/T1 = Q2/T2 which basically says entropy is a property of state given that the Carnot cycle uses Q(rev). Although I recall the above from other sources, it appears to comport with the understanding of Wolfgang Pauli as described in his noted thermodynamics lecture in which he defines S as int(dQ/T) after first deriving T from the Carnot relationship. In case some of the youngsters might not know, Thompson was later known as "Lord Kelvin," after whom the absolute temperature scale was named. Jerry (Ico) DOC0287 Subject: Re: Dehumidifier efficiency From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/14 Message-ID: <4i7or9$n56@geraldo.cc.utexas.edu> Newsgroups: sci.physics,misc.consumers.house,sci.chem In article , Oz says: > >> But on the other hand, maybe it would work best when the air around >>it is warm, since then it will contain more water vapor, and there would be >>a bigger temperature differential between the coils and the air. >> Any opinions? > >It works better when the air is warm for the reason you gave. > Oz, it seems to me that the absolute humidity stays about the same in the evening so the air contains just as much water unless it actually drops below the dew point. Since the humidifier is essentially a Carnot heat pump, it has to pump less heat at the lower temperature and less work is wasted cooling air molecules, whereas the heat of condensation itself is virtually the same. Jerry (Ico) < DOC0288 Subject: Re: Dehumidifier efficiency From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/14 Message-ID: <4i9uti$evs@geraldo.cc.utexas.edu> Newsgroups: sci.physics,misc.consumers.house,sci.chem In article , Oz says: > >In article <4i7or9$n56@geraldo.cc.utexas.edu>, "Gerald L. Hurst" > writes >>In article , Oz >>says: >>> >>>> But on the other hand, maybe it would work best when the air around >>>>it is warm, since then it will contain more water vapor, and there would be >>>>a bigger temperature differential between the coils and the air. >>>> Any opinions? >>> >>>It works better when the air is warm for the reason you gave. >>> >>Oz, it seems to me that the absolute humidity stays about the same >>in the evening so the air contains just as much water unless it >>actually drops below the dew point. Since the humidifier is >>essentially a Carnot heat pump, it has to pump less heat at >>the lower temperature and less work is wasted cooling air molecules, >>whereas the heat of condensation itself is virtually the same. > >Eh? > >Most are just a fan, a fridge unit and a water container. Since the >airflow is relatively high all are on all the time. The cost per hour >will be largely independant of the ambient conditions. > >Generally I know of only two common uses for dehumidifiers as such. > >1) To accelerate the drying of a room or building, usually because of >wet processes (such as plastering) or local flooding. Here the higher >the ambient temperature the higher the absolute humidity and the greater >quantity of water you get out per unit time by cooling the humid air by >delta T since the absolute humidity is nothing like linear in T. >Sticking a couple of fires in the room helps considerably. I have tried >it and it works. Obviously if the air is close to freezing then the >absolute humidity is very low and the walls/floors don't lose much >moisture so their rate of drying is very slow. > Pardon me. I wrote "humidifier" but meant dehumidifier. HAH! You make me laugh, Oz. We are talking about two totally different situations and quite naturally coming to totally different conclusions because we each interpreted the original poster's question in accordance with our perception of his problem. You saw it as a problem of ofsetting the effects of moisture introduced by the user either with wet plaster or a swimming pool. I saw his problem as needing or wanting to reduce the ambient humidity in a room where the moisture is already there as a result of whatever air mass is passing by outside. In my scenario the absolute humidity stays about the same during the daily thermal cycle but the relative humidity swings widely. In your examples, a reduction in relative humidity by heating the air will drop the relative humidity and help dry the plaster. In Texas, when the temperature is over 40 K and RH around 50% we do not heat the room to drop the RH for the sake of comfort :) I Was referring to the energy required per liter of liquid water removed from the air at constant absolute humidity as for instance to maintain equilibrium with a salt solution of fixed concentration. In a manufacturing plant or laboratory where, say, ammonium nitrate is being handled in Dallas, the salt will stay dry during the summer day with RH at 40-50% so little dehumidifying is needed. However, in the early evening the temperature drops enough to raise the RH above 60% and the AN begins to liquify, requiring the dehumidifiers to run full tilt. In this example the efficiency is indeed better at high temperatures as it is in drying plaster. Jerry (Ico) DOC0289 Subject: Re: Help with solubilities / mixed salts From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/14 Message-ID: <4i9vr4$evs@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , haascn@dunx1.ocs.drexel.edu (Charles N. Haas) says: > >In article <4i2iqv$kvq@news.aladdin.co.uk>, tonywilk@aladdin.co.uk wrote: > >> Firstly: If I have solubility data for both KClO3 and KClO4 >> can I directly calculate the proportion of these 2 salts ? >> >> If (as I suspect) not... is there a general rule which >> allows calculation of the solubilities of 2 salts in solution? >> >> I currently can't understand how to draw up a phase diagram >> showing the mutual solubility of two salts, although in trying >> to replicate a diagram for KCl/NaCl (from Perry's) I'm led >> to believe that the Cl in common has a lot to do with the >> reduction in solubility of one salt as the other is increased. > >Tony, the problem is you need additional information, or additional assumptions. No additional information is required in simple theory. Obviously an accurate answer requires assumptions of ideality, but there is a reasonable chance that the accuracy may suffice for the application if the data are correct. At any rate the problem presents an ideal opportunity to practice chemistry calculations - it is a text book question better than most created as exercises. >1) if the two salts are assumed to be present as indvidual pure solids in >separate phases, then their solubility remains unaffected by the presence >of the other. This is incorrect because it ignores the common ion effect. >2) if you form a solid solution, then you need to either assume that the >two components form an ideal solid solution, or have data on the non >idealities. In any event, the common definition of solubility product (as >the product of the ion activities raised to their stoichiometric exponents >) no longer holds, since the activity of the solid phase is no longer >unity (and getting back to the fundamental defintion of an equilibrium >constant, must be considered explicitly). > There is little chance that the two materials form a solid solution and only a remote chance that they form a double salt. Jerry (Ico) DOC0290 Subject: Re: Is CaCl2 a good humidity absorber to protect chemicals ? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/14 Message-ID: <4ia0ct$evs@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4i9n14$1d8c@news.doit.wisc.edu>, Martin Mueller says: > >Bob wrote: >>Is CaCl2 in a plastic jar as good as silica gel to proctect >>chemicals from humidity ? >> >>It is cheap and you can find it anywhere. > >No, it is not in general. While silica gel is more or less inert as a >drying agent, CaCl2 always contains CaO, which means it is basic. >Therefore, it is not a good idea to use CaCl2 for acidic compounds. For >basic and neutral compounds it is as good as silica gel. Martin, you lost me on this one. Why would CaCl2 contain CaO? CaCl2 is a little too soluble to put directly into many liquids, but it is an excellent bulk drying agent for use in dessicators and the like. It is true that it will not reach the absolute low humidity levels achieved by silica gel or calcium sulfate, but it has a voracious appetite for water and yields dry enough air for many purposes. Jerry (Ico) DOC0291 Subject: Re: Making pure ammonium nitrate from fertilizer From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/14 Message-ID: <4i7r6t$n56@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3146e496.0@news-feed.tfi.be>, Bob <> says: > >Is the percentage of nitrogen in the fertilizer of any importance ? > If you're growing crops it is. Jerry (Ico) DOC0292 Subject: Re: Mineral Spirits of Kerosene From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/14 Message-ID: <4i7qsd$n56@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4i1orb$1vc@crcnis3.unl.edu>, dshobe@unlinfo.unl.edu (david shobe) says: > >Gerald L. Hurst (glhurst@onr.com) wrote: >: In article <4hsb79$ove@dfw-ixnews2.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: >: > >: >glhurst@onr.com (Gerald L. Hurst) wrote: >: >>You are told only that they found some material that the >: >>laboratory analyst said was "mineral spirits of kerosene" >: >>at the scene. Later various people ask you as a chemist to >: >>tell them just what it was that was found. What do you say, >: >>and on what do you base your opinion? >: > >: >Unless you can find an industrial or literature reference to "mineral >: >spirits of kerosene" you say nothing. Professional pronouncements ex >: >cathedra carry the weight of personal liability. NEVER defend another >: >person's work with your opinions unless you wish to tightly grasp the >: >tar baby. >: > >: That's fair enough, but now let's ask if anyone amongst us chemists >: has actually seen an industrial reference to "mineral spirits of >: kerosene" or if it is otherwise perhaps a phrase invented by the >: analyst. > >: Jerry (Ico) > > Did the analyst SAY "mineral spirits of kerosene" or did he/she >TYPE it? If the latter I might suggest that "of" is a typo and that >the intended communication was [either] "mineral spirits or kerosene". > -- >--David Shobe > >P.S. "Uncle Al" is right--if the asking is more than a casual "What >do you think?" you would be advised to do a little "research" first: >call the analyst and ask what "mineral spirits of kerosene" are! > Mr. Shobe, I am not a school boy; the question is not casual; I am doing precisely the proper "resaerch" in the proper medium under the circumstances and the question is NOT based on a typographical error or other mistake irrelevant to the sense of the query. Please note that among the present list of postings, the following unrelated message appears under the subject title "Re: Solvent: Mineral spirit ?" Mineral spirit is hydrocarbon derived from kerosine with initial boiling point 140 degc and final boiling point 210 degc. 5% volume max at 150 degc 50% vol min at 180 degc. You will note that the author believes and states that mineral spirits are derived from kerosene. Under this scenario, the the phrease "minerals spirits of kerosene" would be as correct as the concept "mineral spirits of petroleum." It appears that there may be some reason for the authors belief, possibly some published reference, however incorrect. Words have connotations. "Kerosene" and "mineral spirits" are liable to be found in different locations for varying reasons. An analysis which suggests either the equivalency of the two or the necessary presence of one as a consequence of the presence of the other can have severe consequences in the interpretation of the cause and origin of a fire or in the partial identification of a composite product. If we take the concept to its extreme, we might conclude that "gasoline" is subset of asphalt. Now, if you will refer to my original posting, perhaps the nature of my question, its raison d'etre and the reason for including the UseNet in the field of will become evident. Jerry (Ico) DOC0293 Subject: Re: Nitrogen Dioxide Question From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/14 Message-ID: <4i8m6g$jk1@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , alyy@pl.jaring.my (Alvin Leong) says: > >I have a simple question. Why is Nitrogen Dioxide, NO2 brown in color? Is >the reason anything like that for the transition elements where electrons >shift in the d-orbitals? If you know, please please E-Mail me at >alyy@pl.jaring.my and you'll make me a very happy person. I'd like to have as >in-depth an answer as possible. Thanks in advance. :) > NO2 has an unpaired electron which is responsible for the color. When the gas is cooled it dimerizes, pairing up the electron and losing the color. Mixtures of NO and NO2 (brown) freeze to give beautiful a blue or turquoise solid if I remember correctly. The bonding in the alleged solid N2O3 must be interesting. Jerry (Ico) DOC0294 Subject: Re: Solvent: Mineral spirit ? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/14 Message-ID: <4i7p95$n56@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Moty Gendler says: > >Mineral spirit is hydrocarbon derived from kerosine with >initial boiling point 140 degc and final boiling point 210 degc. >5% volume max at 150 degc >50% vol min at 180 degc > Why do you say that MS is derived from kerosene? Are these two materials not merely basically different cuts from the distillation of petroleum which (at least in the US) have distinctly different flash points? If you have a reference describing MS as a being derived from kerosene, I would appreciate your posting the cite. Jerry (Ico) DOC0295 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/14 Message-ID: <4i8h07$jk1@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.energy,sci.mech.fluids,sci.materials,sci.physics Article Segment 1 of 2 In article <31471D10.4F29@hermes.bc.edu>, Keith Ramsay says: >The definition of temperature we are "selling" here has the >virtue of explaining the reason for this equilibrium in terms >of the conservation of energy and non-decrease of entropy, and >doing so without specializing to idealized systems of particles. And how does entropy free us from particles? When we describe the adibatic mixing of gases or liquids, A and B, the entropy increases without the least consequence to internal inergy and fully independently of any temperature changes. Entropy here is associated with nothing more than the fact that the particles of A and B are red and blue respectively in some metaphorical sense. Nevertheless, the "spontaneous" entropy change depends on the existence of particles whose particulate identity may be conveniently awept under the rug by Sterling's approximation. It seems that entropy, then, is a particle function even when those particles do not differ in any but an abstract way. At least the relation of temperature to the hypothetical particle in a box of kinetic theory depends only on the mass and velocity of the hypothetical units, which means it depends only on mass, distance and time, not red and blue. Note here that the ideal gas temperature scale is not derived from the kinetic theory of gases. The latter merely provides insight into the mechanism behind the ideal gas law. The ideal gas scale, again,is not the basis of the thermodynamic scale, it merely helps to validate the derivation of the latter from the Carnot cycle. Finally, the carnot cycle also provided a powerful raison d'etre for the enormously useful concept of entropy. >> Now, the equation dS = (delta Q)/T is certainly valid, but the >> question many might like answered is that if it is to be used >> as a fundamental definition of temperature, to the exclusion of >> other approaches, how can one demonstrate the prerequisite >> definitions of energy (Q), entropy, and the unwritten but >> necessary "reversibility" of the underlying process with reasonable >> simplicity and elegance - the hallmarks of the kinetic theory? > >I think the explanation for why entropy does not decrease is >pretty fundamental. The "number" of states having greater >entropy is larger, and the state of the system tends to wander >out to vaster pastures, as it were, and will not wander back >(unless something like Gold's universe with a future as well as >a past boundary condition holds in the real world). > Yes, but the wandering itself relies on motion which correlates back directly or indirectly to temperature. Eventually the map should fit the physical territory if thermodynamics is to rise above the status of just another mathematical system. In the real world, thermodynamic problems will continually be required to interface with kinetic mechanisms in which T is so very important. Most real questions of equilibrium are concerned with "what" will happen and more often the greater question also demands an answer to "when." >That energy is conserved is also very fundamental. It can be >explained in both classical and quantum physics in terms of >the time symmetry of the laws of nature. > >If an isolated system has no other conservation laws getting in >the way, it will tend to get to the highest possible entropy >given its energy level. > That is true, but that striving may leave the "temperature" totally disinterested in the proceedings of entropy. How often do you find a situation where a change in temperature or temperature distribution is not accompanied by an inevitable change in entropy. In short, entropy is far more dependent on changes in T than vice versa. DOC0296 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/14 Message-ID: <4i8h07$jk1@geraldo.cc.utexas.edu> Article Segment 2 of 2 >If you put two systems, each at equilibrium, side by side, the >combined system will tend to go toward equilibrium, maximizing >entropy. Moving a little energy from system 1 to system 2 will >permit the total entropy to go up if dS/dQ is greater for >system 2 than for system 1. The only way to make energy go >backward while keeping the total energy constant is to decrease >entropy. If you put two systems side by side, their temperatures will always equilibrate Whether their total entropy rises will depend on other things. > >Now, is there a more simple and elegant explanation for why >they tend to go to an equilibrium at the same temperature? >Do we need to drag molecules into the picture at this stage? Molecule per se are never required except for the eminently practical expedient of providing a convenient reference for establishing calibration points and physical standards for temperature measurement. You can escape from real molecules in thermodynamic theory, but not from red and blue particles and those colorful enablers of entropy dance to the tune of temperature. Let me stress that I never deny that temperature can and is sometimes defined in terms of entropy. I do however suggest that such a definition leaves a lot to be desired when presented as "the" definition of temperature. I am not well known for defending the "establishment," status quo, or tradition, but this time I gotta go with the graybeards. Jerry (Ico) DOC0297 Subject: Re: Dehumidifier efficiency From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/15 Message-ID: <4ib378$8mm@geraldo.cc.utexas.edu> Newsgroups: sci.physics,misc.consumers.house,sci.chem In article <4i9uti$evs@geraldo.cc.utexas.edu>, glhurst@onr.com (Gerald L. Hurst) says: >plaster. In Texas, when the temperature is over 40 K and RH >around 50% we do not heat the room to drop the RH for the >sake of comfort :) Those are (K)ermit degrees in Texas, roughly equivalent to (C)elsius degrees elsewhere:) Jerry (Ico) DOC0298 Subject: Re: Is CaCl2 a good humidity absorber to protect chemicals ? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/15 Message-ID: <4iav84$8mm@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <3148389b.845515@news.rmci.net>, jvinson@rmci.net (John W. Vinson) says: > >Derek DeLong wrote: > >>> It is cheap and you can find it anywhere. >The disadvantage of CaCl2 is that, unlike SiO2, it deliquesces when it >absorbs enough moisture (i.e. it turns to a slimy liquid). It also >can't be regenerated. Sure it can be regenerated - just heat it. It only liquifies after it has absorbed a LOT of water. Just take it out before it reaches saturation of its lower ligand water capacity (CaCl2:2H2O) and the solid hydrate then begins to deliquesce as the weakly-bonded hexahydrate. You can regenerate the dessicant at 200C. Jerry (Ico) DOC0299 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/15 Message-ID: <4ibc0f$8mm@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.energy,sci.mech.fluids,sci.materials,sci.physics Article Segment 1 of 2 In article <3148B6F4.35C9@hermes.bc.edu>, Keith Ramsay says: > >Gerald L. Hurst wrote: >You seem to be advocating using a certain sort of definition, >*because* it conveniently gives an important (and idealized!) >case "special" status, and you want to make sure people understand >that special case, and so on. My point is, it would all be somewhat >pointless if it didn't fit into a general scheme, applicable to systems >which are not even made of molecules. > If you were able to read this supposed advocacy into my posts, then I must have failed to express myself adequately. I suspect you have let other's imputations suggest that my inevitable references to particles in tying together the historic relationships between absolute temperature, the kinetic theory of gases, the ideal gas law, the Carnot cycle, and Claussius' entropy somehow prove that I am "advocating" some particular definition of entropy. My personal image of "entropy" happens to be based on probability, but that has nothing to do with the discussion I have been conducting. This thread began with a comment from John Baez which contained a trivial typographical error and an unequivocal statement of *the* definition of "temperature." This dictum was followed by an assertion from another party that that particular definition was the work of or had been accepted by the international committee which adopted the the (Kelvin) definition of "temperature" in the late 1800s. As the discussion grew, there was a strong argument made, and which is still being made, that the most generally accepted definition of temperature in the scientific community in the twentieth century is that promulgated by John Baez and not the definition originated by william Thompson and based on the Carnot cycle. The corollary argument arose that not only was John's definition of temperature the primarily espoused version in the twentieth century paradigm, but that the most widely the most generally repeated and often taught definition of "entropy" was something other than the ubiquitous S = Q(rev)/T or one of its cousins. I disagreed with all of the above. Now you face me with a treatise on why I am wrong in advocating some definition of entropy related to molecules or particles. I have done no such thing. I HAVE described other SPECIFIC approaches to entropy which also use other versions of the particle concept merely to point out that "differentiation" of some sort between classes or species is usually necessary in even the purely mathematical approaches (which I did not address). However, these comparisons should not imply that I have held out one method as better than another, except to the extent that I feel any worthy system must eventually touch our chemo-mechanical world in some way to avoid the obscurity of excessive virginity. I have argued what is and has been a segment of history for better or for worse. It appears for worse, for if you read the rather rambling prose of Doug Merritt and then interpret my writings through his paraphrases, every particle and molecule leaps from my paragraphs like the fiends of some 19th century reactionary Rasputin trying to subvert the purity of modern science by injecting unwanted and unneeded connections with the contamination of the physical universe at early rather than terminal stages. I have said in my miniessays what I set out to say. You seem to believe that I now need a lecture on the superior qualities of methods other than those which I described in their historical context. Since I have clearly failed to convey my opinions and more importantly, my LACK of opinions on the relative merits of various approaches to definitions of entropy, I must resign myself to the fact that it will so remain. DOC0300 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/15 Message-ID: <4ibc0f$8mm@geraldo.cc.utexas.edu> Article Segment 2 of 2 I have written an overly lengthy reply to Merritt's latest God-Save-Baez harangue, but find that it necessarily contains no real substance other than oft repeated denials of authorship of inane ideas ascribed to me. I will not bore you further by publishing that poor document or any additional comments on this topic other than the rhetorical end marker, "Joules/K?" Jerry (Ico) DOC0301 Subject: Re: liquid/solid thermometer..is it possible?? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/15 Message-ID: <4icln5$d10@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4ibdpq$sb5@unidhp.uni-c.dk>, c948296@bohr.gbar.dtu.dk (Lars Juhl Jensen) says: >> >: Basicly what it comes down to I guess is this: Can a solution >: be made in several different percentages of purity (I guess) so >: that each one will have a slightly different melting/freezing >: point? And if so what would the possible solutions/compounds >: possibly be?? water mixed with varying amounts of ?? or any >: other compounds??? > >: This would be for a thermometer such as the ones used in >: ordinary households -50 f to 150 f or so... > >: thanks...its just an idea that is nagging at me... > >Well I think you could make a thermometer this way. Using a >couple of compunds with melting points in the range wanted >and then making use of freezing point lowering for finer >graduation (the freezing point is lowered when impurities >are added - it does not matter what impurities). > >It could be fun to try actually... > Ammonium nitrate/water will work. It has a wonderfully steep temp/soly curve and should do a good job between 150 and bit below freezng. If you gotta get down to -50 F, you might try CaCl2/water Its curve is less steep but it will let you get your liquid very cold. Crystallization may be a bit slow at low temperatures. Jerry (Ico) DOC0302 Subject: Re: Phase Changes: water From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/16 Message-ID: <4idg2i$1l2@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4ica7v$dfm@crcnis3.unl.edu>, dshobe@unlinfo.unl.edu (david shobe) says: > >Jim Goodman (jim.goodman@accesscom.net) wrote: >: In article <1996Mar12.172012@carleton.edu>, erberl@carleton.edu says... >: > >: >Boiling water freezes more rapidly than water at room temperature? - a >: myth? >: >Under what conditions could this ever be true? > >: Somewhere there is the idea that the transfer of heat dE/dt is >: proportional to the the difference in temperature dT: > >: dE/dt = k dT > >: I do not remember where the idea popped up (thermo?), but I think >: it is a misunderstanding of a valid law. For example, if we set out >: to calculate E(t), is it linear in some parameter? > > dQ/dt = k (T2 - T1), i.e. the rate of heat transfer is proportional >to the temperature difference is called "Newton's Law of Cooling". >I don't know whether it is based on a sound physical principle or is >just a linear approximation to a more complex formula. > David, mixing history and science will get you a peck of troubles sometimes in sci.physics, but you might consider that Newton was 75 years old when the first practical thermometer was invented. The nature of heat as a form of measurable energy was still around a century away when he died, so it is improbable that the conduction law bears his name. The above equations look like versions of Fourier's law, remembering that k depends on the phase of the material and is a function of P and T. Jerry (Ico) < DOC0303 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/16 Message-ID: <4idu4q$1l2@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.energy,sci.mech.fluids,sci.materials,sci.physics In article <4icclt$jsq@guitar.ucr.edu>, baez@guitar.ucr.edu (john baez) says: > >Exactly. Workers in quark-gluon plasma physics would find a >18th-century definition of temperature based on steam engines, or even >an early 19th-century definition based on atoms and molecules, rather >beside the point. > John, I understand now why you dislike historical connections in science. There was no 18th-century definition of temperature based on steam engines nor was there an early 19th-century definition based on atoms and molecules. [Snip] >This tremendous generality, and the ease of deducing all the principles >of thermodynamics within this framework, makes it vastly superior to the >18th-century definitions formulated when people only understood a few >special cases, such as ideal gases (which don't even exist except as a >useful mathematical approximation). There was no ideal gas law in the 18th century, no molecules no atoms, no absolute temperature scale. Dalton and Avagadro and Gay-Lussac and Carnot and Thompson all developed the necessary intellectual ingredients in the 19th century. That was a very nice modern definition of temperature you gave. I shall happily add it to my collection. Jerry (Ico) < DOC0304 Subject: Re: Immobilization of carbon dioxide From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/17 Message-ID: <4ii5bg$q8u@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.chem,sci.engr.chem In article , Scott Nudds says: > Loonies who insist or imply that the distribution of temperature >fluctuations are not known are either ignorant of the facts and therefore >incapable of scientific debate, or pretending to be ignorant of the facts >and therefore unwilling to engage in scientific debate. > When one lives in a period between ice ages, it is rather difficult to determine man's contribution to the average temperature. To insist that one *KNOWS* the truth of the matter qualifies you for membership in the Repent-the-end-is-near brigade. >> Whether or not you realize it, I am not obligated to hold >> your beliefs. > > But you are obligated to accept the scientific consensus opinion or >provide respectable technical reasons why the consensus opinion is wrong. >Please do so. If you fail, you will continue to be considered a crank. > The only "consensus" you have is the fraction of people who share your beliefs. I suggest that most scientists still doubt that we have enough data to estimate the earth's temperature fluctuations in the absence of human contributions. Nobody is obligated to believe squat or prove anything. We have not yet sunk to the level of prosecuting thought-criminals or forcing the pledge of allegiance to anybody's pet theory. Jerry (Ico) DOC0305 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/17 Message-ID: <4ignli$3m0@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.energy,sci.mech.fluids,sci.materials,sci.physics Article Segment 1 of 3 In article <314AFDAD.5E8A@hermes.bc.edu>, Keith Ramsay says: > >Gerald L. Hurst wrote: >>[I wrote:] >> >You seem to be advocating using a certain sort of definition, >> >*because* it conveniently gives an important (and idealized!) >> >case "special" status, and you want to make sure people understand >> >that special case, and so on. My point is, it would all be somewhat >> >pointless if it didn't fit into a general scheme, applicable to systems >> >which are not even made of molecules. >> > >> If you were able to read this supposed advocacy into my posts, then >> I must have failed to express myself adequately. > >Oh? Note that I'm not imputing to you the claim that it should be >the only definition to use, ever. You have, however, advocated its >use rather strongly, unless somehow someone has been forging posts >from you. > >One rather key use of a definition is in communication. > >Earlier in the thread, you said: > > The ideal gas temperature scale may now be "obsolete" for > certain purposes, but it is a far better mechanism for teaching > the uninitiated to develop some personal association in their > minds with the interactions of material and energy at least > from the macroscopic and moderately paced perspective of the > older but not yet dead paradigms. > >Far better? Not just better, far better. I haven't seen you withdraw >these claims. > You most certainly will not see me withdraw anything in the paragraph you have quoted. The "uninitiated," who have never heard of Entropy are hardly in a position to use a definition such as the one recently presented by John Baez. John's definition was a humdinger, but hardly suitable for the vast majority of students learning to use science and mathematics as a map for the physical territory those students have trod but not understood to any degree. If we were to adopt the simpler definition, which John first suggested T = dE/dS, a basic restatement of the second law at the expense of teaching the historical ideal gas approach, we would simply create even vaster hoards of semiliterate scientists and engineers who could regurgitate but understand not at all. Again you are in confusing an argument relating to to ORDER in which ideas are taught with an argument for the inherent quality of two definitions. The distinction is not subtle, but it appears difficult to grasp by many here. Most of the arguments I have seen here which denigrate the importance of history are by people who have exhibited an astonishing ignorance of that same history. So much is this the case, that I now realize that most of the advocates of the supremacy of newer definitions are abysmally ignorant of the fact that even those definitions rely on the dog-eared old methods of the ideal gas law to calibrate the scales. "dE/dS" is only a "conceptual definition." It cannot by itself produce a scale on which you can assign a triple point to carbon dioxide unless one uses that point as an arbitrary anchor for the system. When I described the definition of "temperature" as it was first proposed by Thompson and and later adopted international agreement, I did not say "PV = nRT," but rather I described in many words an entire scheme which takes one from the Carnot cycle, an expression of the second law through the theoretical ideal gas law to the real gas thermometers which are still used today, again by international agreement. Even when one uses the most abstract of concept definitions as a starting point, it is the actual gas thermometer which acts as the basic standard for the international temperature scale (ITS) with its myriad of reference points. The ITS90 scale which came into force on January 1, 1990 is no different - it still relies on the ideal gas law and its practical implementation in the form of the real gas thermometer. The gas thermometer is augmented by the acoustic thermometer, which again depends on ideal gas relationships. DOC0306 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/17 Message-ID: <4ignli$3m0@geraldo.cc.utexas.edu> Article Segment 2 of 3 You were not listening when I pointed out that the entropy concept is contained in the carnot cycle, from whose reversible processes the equality Q1/T1 = Q2/T2, i.e.,constant entropy, descends and from which process Thompson PARTLY derived the definition. Thompson incorporated the real gas thermometer in the overall method two years later and the whole schema was adopted in 1887. There have been many adjustments to that scale since then, but the primary standard is still the REAL gas thermometer, still interpreted by extrapolations of the ideal gas law to extreme conditions to remove the vestiges of nonideality. Again I am not arguing "PV=nRT" vs "dE/dS = T"; "PV = nRT" is merely part of a larger system that may start with Carnot or the entropy concept (which is inherent in Carnot) derived from some more abstract definition. When Thompson finally incorporated the ideal gas concept into his already existing CONCEPTUAL definition, he had extensive experience in the experimental investigstion of the NONIDEALITY of real gases. He and the international committee who later accepted his system, nonideal warts and all, knew exactly what they were doing and why. Their example has been followed by all succeeding international authorities for reasons which are still valid today. There seems to be some idea here that it is only in the recent years that minds have expanded to the "modern" concepts which were unknown to the generations of teachers who have taught at least the elements of the way our latest international scales have been defined. It is this group who have gotten swept up into the odd notion that earlier generations were too ignorant to understand the finer points of good teaching methods. Perhaps this is because you represent the first generation of college graduates who were required only to learn their math and quantum mechanics without any sense of either the history of their subject or the actual mechanics of bridging from the theoretical to applications in the real world where measurements must actually be made. Reread some of the posts of your supporters and note the pride they take in their ignorance of "ancient history." Do you really think that Wolfgang Pauli was too ignorant to understand modern approaches to physics when he used the classic textbook definitions of temperature and entropy in his lectures on thermodynamics in Switzerland? He obviously made a conscious choice that thousands of other knowledgable scientists have made. In so doing, he was not expressing an opinion on whether one definition is "better" than another, but he was definitely favoring one teaching approach - not for specialists but for scientists in general and for those who would never make the grade but would at least know from whence those numbers called "K" originated. Again, for those whose reading comprehension and historical knowledge are not quite on par with their mathematical aptitude and training, I do not have any opinion on which elementary mathematical expression of either temperature or entropy is "Better" or more "sophisticated." I do suggest that the long version of the definition of temperature, as I have outlined it, is not only the best FIRST lesson, but should be mandatory in addition to any other versions that are taught. If you can succeed also in implanting more sophisticated notions, go to it. One lesson is not learned at the expense of the other. Our future generations will be better off if we make sure that the current crop of scientists is the last to lack both historical knowledge and hands-on experience. We will profit if the world's scientists know how things are actually done and why. When I said that I suggested that we at least look at the possibility that our teaching methods leave something to be desired, I wasn't simply referring to some individual definition. BTW, yes, William Thompson (Lord Kelvin) WAS an engineer, but he also did a journeyman's job as a scientist. DOC0307 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/17 Message-ID: <4ignli$3m0@geraldo.cc.utexas.edu> Article Segment 3 of 3 >I also tend to think your calling the statement of another definition >"possibly true as a pronouncement of the latest committee" to be >intended to leave the impression that it is not so hot, at least from >a longer-term point of view. I did not call *another* definition "possibly true as as a pronouncement of the latest committee." I said that of *THE* definition. My statement was too mild. The latest real international committees have not adopted any such definition. If there is such a "committee" worth mentioning it is well hidden from rank-and-file scientists. I made the mistake of assuming that John knew something about some important formal resolution that I did not. It appears that despite our having been told of such a committee from the 1800's, the only real group consists of a few current mathematicians with a proclivity for algebraic transposition. The "sophisticated" definitions per se are ok until it comes to explaining to the students why the units of entropy in the handbooks are given as Joules/K, which is kind of like listing the second in units of joules, grams and centimeters. This sort of thing works better in a mathematics book than in some pchem classes. If I seem to be giving you folks less credit than before, it's because I've thought and read a bit more and looked into some of the more far-out thermo systems without finding much support for your positions. In that same period I have noted that the most vocal arguments against the classical approach come from those who know the least about it. If I am perceived as backsliding, chalk it up to the pull of the weight of the evidence that some (not all) of the arguments for more "sophisticated" definitions as general educational fare are the smoke of pipe dreams. Jerry (Ico) DOC0308 Subject: Re: Immobilization of carbon dioxide From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/18 Message-ID: <4ij672$fo8@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.chem,sci.engr.chem In article <4iiu4v$ltr@allinux2.alliance.net>, mjones59@mail.alliance.net (MarkJones) says: > >Would Washingtom, Michigan and other northern states become the Sauli >Arabia of the USA? I live up there and would tell the rest of the >desert west to go to hell just like we do when they want our water!!! > Relax Mark. You need to travel around a little to lose that provincial attitude. Some of your best friends are probably "Winter Texans," who will need a cool glass of water after they thaw out. When does the secession begin :) Does this mean we don't get to cut down all the trees and pave everything north of Oklahoma? Jerry (Ico) DOC0309 Subject: Re: Immobilization of carbon dioxide From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/19 Message-ID: <4il5pd$4nd@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.chem,sci.engr.chem In article <4ij9vu$2t0@main.freenet.hamilton.on.ca>, af329@freenet.hamilton.on.ca (Scott Nudds) says: > >Gerald L. Hurst (glhurst@onr.com) wrote: >: I suggest that most scientists still doubt that we >: have enough data to estimate the earth's temperature fluctuations >: in the absence of human contributions. > > And if the nature of the debate were "in the absence of human >contributions", you would have a significant point. Unfortunately the >debate is concerning human induced climate change, so your observation >has no applicability. > Sorry, I assumed you were looking at the problem scientifically. I won't bore you with the details, but in general, if you wish to measure the effect of a specific agent on a system it is necessary to have a reasonable measure of the base-line behaviour of the system in the absence of the agent. >: Nobody is obligated to believe squat or prove anything. > > Those who have no expertise and argue the consensus opinion >are fools. To the extent that people are not obligated to be more than >fools you are correct. I would assume the above author considers himself >something more than a fool however. Hence he is obligated. > Sounds like something that came out of a fortune cookie. You are still using "consensus" to describe the people who believe as you do. Or perhaps you mean "Forty million Frenchmen can't be wrong." Jerry (Ico) DOC0310 Subject: Re: Phase Changes: water From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/19 Message-ID: <4il4pg$4nd@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <314DF632.3926@ifu.net>, Jason Tiscione says: > >Gerald L. Hurst wrote: >> In article <4ica7v$dfm@crcnis3.unl.edu>, dshobe@unlinfo.unl.edu (david shobe) says: >> >Jim Goodman (jim.goodman@accesscom.net) wrote: >> >: In article <1996Mar12.172012@carleton.edu>, erberl@carleton.edu says... >> >: >Boiling water freezes more rapidly than water at room temperature? - a >> >: myth? >> >: >Under what conditions could this ever be true? >> >: Somewhere there is the idea that the transfer of heat dE/dt is >> >: proportional to the the difference in temperature dT: >> >: dE/dt = k dT > >You quoted the equation wrong. dE/dT=k(T-T0) where T0 is ambient temp. >"dT" is an infinitesimal. I think he meant dE/dt = -(K/A)*dT/dx, where A is the cross sectional area normal to the heat flow along direction x. This is Fourier's law. > >> >: I do not remember where the idea popped up (thermo?), but I think >> >: it is a misunderstanding of a valid law. For example, if we set out >> >: to calculate E(t), is it linear in some parameter? > >> >dQ/dt = k (T2 - T1), i.e. the rate of heat transfer is proportional >> >to the temperature difference is called "Newton's Law of Cooling". >> >I don't know whether it is based on a sound physical principle or is >> >just a linear approximation to a more complex formula. > >Newton's Law of Cooling is a very good law. You can add higher order >terms to the linear dQ/dt equation but there won't be much of a deviation >from the linear approximation. Unless phase changes are involved, and when >you pour boiling water in an ice cube tray... > For the simplified condition where dT/dx is constant then for a given length and area, dE/dt = k(T2-T1) as in your equation where your "proportionality constant, k = -K*A/(x2-x1) and my big K is known as the "coefficient of thermal conductivity." Simplified though it is, Fourier still gets the credit, not Newton. >> David, mixing history and science will get you a peck of troubles >> sometimes in sci.physics, but you might consider that Newton was >> 75 years old when the first practical thermometer was invented. > [Snip Newton, a bitter man at the mint.] >> The nature of heat as a form of measurable energy was still around >> a century away when he died, so it is improbable that the conduction >> law bears his name. > >WRONG! dQ/dT=k(T-T0) IS Newton's Law of Cooling. Whether it was his >or just named in his honor is another matter. But, that's the name. > As a general rule, laws are rarely named after people who knew nothing of the subject matter of the law. Perhaps the people who named this particular law after Newton did so as a lark after a snoot full of Bay Rum. If that is the case, then I, having no more but no less authority (yet more sense) than they, hereby declare that the name shall henceforth be Fourier's law. Now that you have seen the declaration in print, it must be true. Jerry (Ico) DOC0311 Subject: Re: Phase Changes: water From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/19 Message-ID: <4il8j0$4nd@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , "J. M. Woodgate" says: >Nevertheless, Newton _did_ formulate his Law of Cooling as Jim Goodman >states. It strictly applies in the case where the cooling object is in a >continuous air-flow. In still air, the rate of cooling is proportional to >the five-fourths power of dT, and this is (or was forty years ago) as the >'five-fourths power law'. Newton may well have formulated rules giving a cooling rate with respect to time for an object. He could even conceivably have used a Fahrenheit thermometer in his later days. It is quite possible that someone assigned the apellation "Newton's cooling law" to his observation and formulation. However, the expression dE/dt requires a knowledge of the existence of heat energy as a measurable quantity. Fourier was only able to derive his law because of the work of a number of people who were born long after Newton's death in 1727. A "cooling law" requires only an expression of the sort dT/dt = f(T) and the two variables can be measured using only a thermometer and a timing device such as a clock or the human heart. The concept of energy seems very obvious to us now, but back then "phlogiston" was not quantifiable. In short, Newton had the tools to define a limited "cooling law," but not a heat conduction law. Today we would look for kinks or loopholes in a "cooling law" as indicative of exothermic or endothermic events in differential thermal analysis. Jerry (Ico) DOC0312 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/19 Message-ID: <4ilqr7$lhc@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.energy,sci.mech.fluids,sci.materials,sci.physics In article <1996Mar19.051115.8793@pmafire.inel.gov>, russ@pmafire.inel.gov (Russ Brown) says: >>There was no ideal gas law in the 18th century, no molecules no >>atoms, no absolute temperature scale. Dalton and Avagadro and >>Gay-Lussac and Carnot and Thompson all developed the necessary >>intellectual ingredients in the 19th century. >> >Before dancing too far on thin ice, you might want to consider > > 1) L. Boltzman, Populare Schriften (1905) > > 2) L. Boltzman, Weitere Studien uber Warmegleichgewicht unter > Gasmoleculen, Sitzungberichte der K.Wiener Akademie, and > his Lectures of Gas Theory (Berkely, 1964). > Let me guess: 1. You're testing me to see if I know that Ludwig spelled his name with 2 n's ? 2. You believe that since he was born in 1844 his work on "Further Studies of Thermal Equilibrium in Gas Molecules," published postumously, proves that the ideal gas law or the absolute temperature scale was developed in the 18th century? 3. You believe that 1844 was in the 18th century? 4. You were wondering if I speak German? 5. You believe that Boltzmann published a paper in 1905 on the problems of dancing on thin ice? 6. You had absolutely nothing to say, but you said it anyway? Jerry (Ico) DOC0313 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/19 Message-ID: <4inc9t$24m@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.energy,sci.mech.fluids,sci.materials,sci.physics Article Segment 1 of 2 In article <1996Mar19.135921.9793@pmafire.inel.gov>, russ@pmafire.inel.gov (Russ Brown) says: > >No. And you lose a point on "posthumously". :) >You lose half a point for not catching the incorrect typing of "Berkeley". > You are quite right. I dropped the "h," which was careless of me. I really should take more time to proofread my postings. Ah, so you were referring to the city in california. >No. The resolution of questions about scientific principles is not >limited to historical niceties. You seemed somewhat excited, too. There is not and has not been any discussion of "scientific principles" by me. This discussion deals with a matter of perspective and in particular with the question of whether there is only one acceptable "definition" of the "temperature." The specific post to which you made your less than relevant comments about Boltzmann had absolutely zilch to do with the accuracy of my comments concerning the time frame of the development of theories relating to ideal gases. Once more we hear the endorsement of the banality of a group which actually takes pride in their lack of historical perspective. In particular, references to Boltzmann and his work do not contribute much to the support of dogmatic argumments regarding temperature definitions. Part of Boltzmann's fame rests on his work on the kinetic theory of gases, which is a two-edged sword in an argument advocating definitions based solely on his other work on the relation of entropy to probability. Remember that Boltzmann's constant is also called the molecular ideal gas constant. How do you suppose the numerical value of his famous constant was first determined, Bubele? Here's are three bits of perspective from the *Encyclopedia of Physics* A precise distinction between kinetic theory and stastical mechanics cannot be made. The latter is usually more formalized but utilizes the same basic laws of mechanics and collisions. Statistical mechanics is generally regarded as the aspect of kinetic theory that deals with interpreting thermodynamic quantities like entropy and free energy by molecular collision analysis. and, with regard to the derivation of the Maxwell-Boltzmann law: Finally recourse to Jopule's derivation is taken wherein the mean molecular kinetic energy arises from (1/2)mc^2 = (3/2)(R/n)T = (3/2)kT The molal gas constant R, divided by Avagadro's number n, is called Boltamann's constant and is represented by k. and, finally The Kelvin temperature of an ideal monatomic gas (thus of a real monatomic gas at sufficiently low density and pressure), for example, is given by T = (2/3k)E, where E is the mean kinetic energy per atom and k is the universal Boltzmann constant. More complicated relations hold for more complicated systems; they all support the the generalization that higher temperature is a macroscopic manifestation of more energetic molecular and submolecular motion. This generalization is for many scientists the essence of the temperature concept. >Never did. But in 1906, he committed suicide, having become depressed >about the scientific establishment's hostility to his work. Buried in >the Zentralfriehof in Vienna, his tombstone was engraved with the >commendable (for all, even you) relationship, S = k ln(W). Why did they bury his tombstone and if it is buried, how do you know what is written on it?:) Remember that k is R/N and is expressed in J/K. Wasn't it nice of lord K to provide that K What conceit leads you to believe that simply because I deplore your obvious ignorance of history and do not share your particular myopia, that I am less capable of appreciating intellectual achievement than you? If they had not chisled it in stone, would the feat have been any less admirable? Catchy epitaphs copied from the encyclopedia are not what I had in mind when I suggested learning a little history. >> >>6. You had absolutely nothing to say, but you said it anyway? > >"Nothing" seemed appropriate for a conversation that had degraded to >personal exchanges. DOC0314 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/19 Message-ID: <4ine48$24m@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.energy,sci.mech.fluids,sci.materials,sci.physics In article <4im65d$no6@lyra.csx.cam.ac.uk>, dna1000@cus.cam.ac.uk (David Allsopp) says: >>simply create even vaster hoards of semiliterate scientists and > ^^^^^^ ^^^^^^^^^^^^ >>engineers who could regurgitate but understand not at all. > >I think you mean 'hordes', unless someone is stockpiling scientists. >What what that about semiliteracy? 8-) Nope, I meant "Hoards." However, I well remember the equally appropriate but different mental picture of the "marching hordes of Ph.D.'s from the ancient tome entitled "The Education of T.C. Mits." We keep our hoards of hordes of physicists in the taxi stations of our great nation where we have enough in reserve for a generation to come. I like the word "herds" or "armies" or "marching bands" better for the ACTIVE masses symbolism, because of the added connotations of follow-the-leader mentality. BTW, if you judge literacy by good spelling, then you can happily classify me as illiterate. I have no particular facility for spelling and I have no inclination to waste time learning to spell any better than I do now. I suppose I could use a spelling checker or at least do more proofreading, There you have good reason to add lethargy to my personal defficiencies it pleases you. Despite my own mediocre abilities, I can still comment to my heart's content on the pitiful level of education among young scientists. I am surprised that my individual shortcomings are worthy of comment, but if it pleases you, have at it. Jerry (Ico) DOC0315 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/19 Message-ID: <4inc9t$24m@geraldo.cc.utexas.edu> Article Segment 2 of 2 It is sad that you admit being drawn into a discussion merely by the attraction of "degraded personal exchanges" when you had nothing of value say. I have tried to turn a sow's ear into a silk purse by usuing your vacuous post as an excursion point for some observations on perspective. I do not expect you to break your lockstep with the marching band of the sci.physics mafia, but consider the possibility that there might be other valid viewpoints. Jerry (Ico) DOC0316 Subject: Re: A question about carbondioxide From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/20 Message-ID: <4inkeq$adv@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4iml22$8mb@reader2.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: > >hahnh@ix.netcom.com(Hyeok Hahn ) wrote: >>I recently doing some project about soda(in a PET-bottle). >>But all the hand book in our university's library didn't cover this >>subject. >>How can I get the concentration in atmosphere during summer day. >>And how can I get the concentration of carbondioxide in the coke? >>(All I could find about this concentration is that of a bear and >>I also couldn't understand its meaning... it says " CO2 volume." >>Thank you. >> >>H.Hahn > >A recent CRC Handbook of Chemistry and Physics will have a table of CO2 >concentration in air by month and year. > >As for the CO2 in Coke... get a large balloon and weigh it. A big >Mylar balloon is best because it is not elastic - it will inlfate at >ambient pressure. Secure the open end of the balloon over the top of a >warm bottle of Coke, then open it by unscrewing (grasping it through the >balloon). Shake gently then well (or drop in a magnetic stir bar and >have at it). When everything comes to equilibrium, remove the balloon so >as not to lose gas, tie its open end into a knot, and weigh it again. > >Account for the CO2 still in solution at low pH at atmopsheric pressure >(they don't chug in all that phosphoric acid for nothing), and you have a >pretty good estimate. > It might be a good idea also to acount for the buoyancy of air, which will give a CO2 mass value roughly roughly triple what the balance tells you. Jerry (Ico) DOC0317 Subject: Re: Blowing Bubbles From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/20 Message-ID: <4ipst8$c8h@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.materials In article <4inqrr$jh2@cloner2.ix.netcom.com>, Alan \"Uncle Al\" Schwartz says: > >Snell wrote: >>I am looking for a material or chemical substance that can be used to >>make lighter than air bubbles that will have an exterior coat that will >>become solid, and still be lighter than air. IE: The bubbles, after >>becoming hard, must retain a positive buoyancy, as this will mostly be >>applied in my underwater/surface projects. >> >>Other factors: >> Cost of the material, >> Supply of the material, >> Simplicity to make bubbles using the material, >> Toxicity of the material used. >> >>Gas used inside the bubble will be helium, or hydrogen. Fire is not an issue. > >You can buy hollow glass or silica microspheres in several sizes and >wall thicknesses ( http://www.thomasregister.com ), as well as hollow >ceramic or epoxy macrospheres used to make syntactic foams (can't crush >under pressure). You can easily get 30% void space in cast resin. > >I suppose you could take the microspheres and heat them in a vacuum oven >to a couple of hundred C for a week or two, or in a furnace around >a vacuum ampoule (dynamic vacuum) to maybe 400 C tops. The air will >slowly diffuse out and at those temps the bubbles should not sinter or >inflate. I don't think they will hit negative boyancy in air. > Glass microballoons already have a vacuum inside, but there is no way anyone is going to make them air-buoyant. I you want air-buoyancy and solidity, like Al says, you're going to need something large like a so-called "Mylar" balloon. A glass sphere or the like, light enough to float in air when filled with hydrogen, can be made in roughly lightbulb size, but is much too delicate and frangible to work under water. In theory, you could scale such a balloon down to "bubble size," but such an "aerogel" weight bubble would be a very fragile feat of advanced art. Jerry (Ico) DOC0318 Subject: Re: Immobilization of carbon dioxide From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/20 Message-ID: <4ipr10$c8h@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.chem,sci.engr.chem In article <4iof65$1t4@phunn1.sbphrd.com>, Frank_Hollis-1@sbphrd.com (Triple Quadrophenic) says: >And only non-fools are allowed to participate in our >democracy (lunatics and peers are not allowed to vote). > The results do not confirm the truth of the allegation. Jerry (Ico) DOC0319 Subject: Re: Immobilization of carbon dioxide From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/20 Message-ID: <4inkir$adv@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.chem,sci.engr.chem In article , Scott Nudds says: > > > >On Mon, 18 Mar 1996, dcwhite wrote: >> How would you propose we solve the carbon dioxide problem? > > The first step is to admit that the problem exists. Since I am not a >coward, or a fool, I took this step a long time ago. > Two out of three ain't bad. Jerry (Ico) DOC0320 Subject: Re: Phase Changes: water From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/20 Message-ID: <4io8k7$adv@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4ik6h0$1hn@crcnis3.unl.edu>, dshobe@unlinfo.unl.edu (david shobe) says: > >Gerald L. Hurst (glhurst@onr.com) wrote: >: In article <4ica7v$dfm@crcnis3.unl.edu>, dshobe@unlinfo.unl.edu (david shobe) says: > >: > dQ/dt = k (T2 - T1), i.e. the rate of heat transfer is proportional >: >to the temperature difference is called "Newton's Law of Cooling". >: >I don't know whether it is based on a sound physical principle or is >: >just a linear approximation to a more complex formula. >: > >: David, mixing history and science will get you a peck of troubles >: sometimes in sci.physics, but you might consider that Newton was >: 75 years old when the first practical thermometer was invented. >: The nature of heat as a form of measurable energy was still around >: a century away when he died, so it is improbable that the conduction >: law bears his name. > > The equation is referred to as Newton's Law of Cooling in >_Heat Transfer_ by Alan J. Chapman (p. 13 in 3rd ed.). Again, I >don't know the history. It is an estimate of the rate of heat >transfer from an object to its environment by all mechanisms, not >just conduction. David, either your author has written inacurate information or perhaps you have misinterpreted something. Newton did not have the necessary knowledge of the concept of heat energy to define a law dealing with its flow. He could certainly have measured and described a generalization about cooling rates if he had wished to since various types of thermometers with arbitrary temperature scales had been invented as far back as Galileo, and Fahrenheit had brought out his alcohol and mercury thermometers a dozen years or so before Newton's death. If you take the "heat" out of the story it would play better in Peoria. Why don't you hum a few bars from _Heat Transfer_ by Alan J. Chapman (p. 13 in 3rd ed.) and we'll see if we know the tune (quote, please). >*** radical change in subject *** > > As you might guess I am new to sci.chem, and don't know what >rules of 'netiquette' apply. It appears that this is *not* an >open discussion forum, and that only certain people are allowed >to answer questions. > It is a very open forum, but only I and Uncle Al and Archimedes Plutoni are allowed to speak with authority. Sorry, just kidding. You can say what you please with no worse consequences than being yelled at in capital letters. If you can stand the caps you've got it made. If you think you've got it bad, you should see the lynch mob that's after me in sci.physics. Over there it's not just big letters - they know ascii characters that are banned in Boston. Jerry (Ico) DOC0321 Subject: Re: [Q] Energy of atoms in molecules From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/20 Message-ID: <4invic$adv@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.energy,sci.mech.fluids,sci.materials,sci.physics In article , meron@cars3.uchicago.edu says: > >In article <4inc9t$24m@geraldo.cc.utexas.edu>, glhurst@onr.com (Gerald L. Hurst) writes: > > ... big snip ... > >>I do not expect you to break your lockstep with the marching band >>of the sci.physics mafia, but consider the possibility that there >>might be other valid viewpoints. > >Hey, "mafia" implies organization (as in "organized crime"). I can >think about various less then flattering descriptions of sci.physics, >but "organized" isn't one ot them. > Are you kiddin'? Since I posted that message I've learned that the Nobel committee is no longer considering my nomination, and I'm being sued by the Cosa Nostra for defamation. Jerry (Ico) DOC0322 Subject: Re: patron saint From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/20 Message-ID: <4iprk8$c8h@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <31507F16.7C1@chem.kuleuven.ac.be>, Peter Carly says: > >Who is the patron saint for the chemists? Is there one for each >discipline? Other than St. Amorphous and Pope Intractable, whose canonization is disputed, I cannot think of any Jerry (Ico). DOC0323 Subject: Re: Immobilization of carbon dioxide From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/21 Message-ID: <4iq7o3$ph9@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.chem,sci.engr.chem In article <4ioto4$j2s@main.freenet.hamilton.on.ca>, af329@freenet.hamilton.on.ca (Scott Nudds) says: > >Triple Quadrophenic (Frank_Hollis-1@sbphrd.com) wrote: >: If Gerald has some expertise (no matter >: how small) then he can argue against the consensus and not be classified as >: a fool. > > If Gerald shows himself to be technically competent, then he has the >right to object and remain in good standing. > > The probability of that is near zero however. > How sharper than a serpent's tooth is a zealot scorned. Of course I'm technically competent. I took science in junior high and did quite well, and I know what most of the buttons on my Iron Man watch do. Jerry (Ico) DOC0324 Subject: Re: Immobilization of carbon dioxide From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/21 Message-ID: <4iq7bj$ph9@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.chem,sci.engr.chem In article <4iotj7$j2s@main.freenet.hamilton.on.ca>, af329@freenet.hamilton.on.ca (Scott Nudds) says: > >Gerald L. Hurst (glhurst@onr.com) wrote: > Please provide a peer review reference to a Global Climate Model that >predicts cooling in response to increased CO2. Please provide a list of >Peer review articles that predict cooling in reponse to increaed CO2. > > If there is no consensus on the quesiton of CO2 induced global warming >then there must by definition be an equal number of papers predicting >cooling as there are papers predicting warming. The same is true for >Global Climate Models. > > If you are unable to provide references (and you will be), we can (and >will), easily conclude that your insistance that there is no consensus is >based either on abject ignorance of the subject or or a desire to lie for >political reasons. > > I await your refrences before I draw any conclusions. It looks like you've got a long wait in store. I suppose it saves a lot of time when you decide on the nature of both or all ten sides of a discussion. According to your instructions I am supposed to take the side that CO2 in the atmosphere doesn't tend to increase global temperatures. I'm sorry but you'll have to keep arguing both sides of that point yourself until you can find somebody more pliant to argue that increased CO2 is responsible for ice ages. Counting the number of publications proposing some theory is a very dodgy way of arriving at a "consensus" of what "scientists" think. If this method worked, we could easily determine that both polywater and cold fusion are generally accepted. Just think how many publications dealt with phlogiston, before it got very quiet. Do you happen to know what concentration of CO2 climatologists believe was typical prior to the last ice-age? We don't merely spew out CO2, we also shove zillions of pounds of particulates into the atmosphere. How much cooling effect is that going to have? Maybe we're going to bring on a new ice age and then we'll need to shove some more CO2 into the air to compensate. Perhaps the increased CO2 will lead to an explosion of green carbon dioxide-sucking monster algae which will generate so much oxygen that we will perish in a holocaust of fire. Then the planet can start all over with the freshly made gas. So many questions and so few climatologists. Jerry (Ico) DOC0325 Subject: Re: CO2 Reaction Question From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/22 Message-ID: <4itlqm$f0s@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4it1nc$e2j@newsbf02.news.aol.com>, brianburt@aol.com (BrianBurt) says: > >I desperately need the expertise of someone well versed in chemistry to >answer the following question! > >I am starting work on a science fiction novel in which I need a very >specific type of (hypothetical) chemical reaction to satisfy some central >requirements of the plot. Carbon dioxide and seawater need to be two of >the reactants, and the reaction must: A) be highly exothermic (the more >violent, the better); and/or B) generate toxic product(s) (the more >lethal, the better). I have been using as a working premise some type of >"mysterious" organometallic reactant/catalyst that, combined with CO2 and >seawater, yields a carbonate (possibly calcium carbonate?) and explosive >quantities of waste heat... but I'm not a chemist, and I don't know if >this type of reaction is realistic or a candidate for satisfying my plot >requirements. > >Any advice, guidance, or suggestions anyone out there can provide would be >gratefully accepted and much appreciated. (I promise to give proper >credit in the book's acknowledgements.) Thank you in advance for any >input you can offer! > Why not? Here's one that at least allows the suspension of disbelief. Aluminum is added to many explosives because it reacts in such a way as if it gobbled up the water either present in or produced by the explosion. Some of these explosives are actually water solutions of such things as ammonium, calcium or sodium nitrate or even the odd perchlorate. Although nobody knows exactly why, the hypothetically quite reactive mixture of aluminum and water does not react explosively when smacked with a blasting cap or primer unless an unspecified amount of oxidizer is added. You can be pretty certain nobody has ever tried CO2/Water/Aluminum powder at high concentrations of CO2 (High pressure). Since CO2 is liquifiable under pressure you can use pressure to create any mixture of CO2/water you wish. If you say that that mixed liquid, combined with aluminum powder, will detonate or at least explode under confinement, nobody can prove you wrong. You can even speculate that the carbonic acid present from the reaction of CO2 with water cleans the oxide film off the aluminum and sensitizes it. If the creative license bothers you, just add some oxidizer to the brew, in the form of, say, ammonium nitrate and you've got the first metallized explosive soda "POP" blasting agent. Jerry (Ico) DOC0326 Subject: Re: CO2 Reaction Question From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/24 Message-ID: <4j340p$anc@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4j29ct$1lk@mojo.eng.umd.edu>, candela@Glue.umd.edu (Philip Candela) says: > >With regard to some other comments on this thread: note: liquification of >CO2 at pressure does not ensure mutual solubility -over a range of T's and >P's there is a considerable field of liquid immiscibility betweem liquid >CO2 and liquid Water. the addition of NaCl to this system can extend the >immiscibility to many hundreds of degrees(C) and a few kilobars (Deep >ocean water at 6.7 km is at a pressure of about 670 bars). In fact >natural inclusions of fluid in quartz crystals at room temperature can >contain vapor+liquid CO2 +liquid H2O (the quartz xl acts as a pressure >vessel - the total mechanical pressure in such inclusions can be high) > I have a little trouble with your data. According to my references, the critical temperature and pressure of CO2 are respectively 31 C and 72.85 atm, which, if correct, means there is no liquid phase of CO2 above 31 C and therefore no immiscible liquid phase "at many hundreds of degrees (C)..." At lower temperatures I would expect high pressure to drive the equilibrium to the carbonic acid side. There are a lot of chemists working on liquid CO2 systems these days, so someone is sure to straighten us out. Jerry (Ico) DOC0327 Subject: Re: CO2 Reaction Question From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/26 Message-ID: <4j9gck$olh@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4j8ckt$mdr@mojo.eng.umd.edu>, candela@Glue.umd.edu (Philip Candela) says: > [Good stuff snipped] >I hope this clears things up. Again, my apologies for turning an >interesting question re: "novels" into a lecture on physical chemistry. > >Any comments welcome. > No apologies needed. The information you provided on NaCl/H20/CO2 phases was fascinating and (to me) very surprising in terms of the enormous effects of relatively minor concentrations of salts on the critical properties of water solutions, not to mention the CO2/H2O system. If you have some additional cites handy, I'd appreciate some email, but there are probably others here who would welcome more information. Jerry (Ico) DOC0328 Subject: Re: CopperChloride From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/26 Message-ID: <4j9ron$olh@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4j9k2t$4dj@nms.telepost.no>, Beavis says: > >Can anyone explain why copperchloride (CuCl2) has one copper atom and two >chloride atoms. One would think that since the copper atoms has only one >valence electron it would make pairs with just one chloride atom, just >like sodium (NaCl) ???? > If it's any consolation, Beavis, copper also forms a Cu(I) chloride, Cu2Cl2. It is able to form Cu(II) compounds by losing one of its d subshell electrons to leave that subshell one short of a full house. Other transition elements also dip into the d level form species like Ni(II) and Co(III). Jerry (Ico) DOC0329 Subject: Re: Know your limits ! (reply) From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/26 Message-ID: <4j8dno$59h@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.geo.rivers+lakes,sci.chem.analytical,sci.geo.oceanography,sci.chem.organomet,sci.environment,sci.geo.geology,sci.geo.hydrology In article <4j6uut$pjg@niamh.indigo.ie>, clavin.rubicon@indigo.ie (rubicon) says: > >While you're doing all of this learning, you might find the time to learn >how to spell - very usefull for getting good grades. > Useful(l)? Jerry (Ico) DOC0330 Subject: Re: looking for info... From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/03/28 Message-ID: <4jctee$bsp@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4jb5v2$edf@Axil.wave.co.nz>, Peter@rjhill.co.nz (Peter Robinson) says: > >In article <4j29nq$1m8@impsrv1.imp>, babucher@mtu.edui says... >> >> >>Is there a place on the net I can telnet/www/gopher/whatever >>to that I can use to look up information on compounds, such as >>specific gravities, blah blah... >> >>Also, what would 'turpentine' be under in the CRC Handbook of Chemistry >>and Physics? It's not in the T's under organic or inorganics. > >Kia Ora Boo > >Turpentine isn't in the Rubber Handbook because it is not a pure compound - try >alpha or beta pinene which are major constituents. Turpentine was (is?) >extracted from the wood of various species of pine trees, often as a by-product >of paper manufacture. This form has been largely supplanted, as a paint >thinner anyway, by "mineral turps" which is a hydrocarbon blend with no >chemical relationship to the original, it's just used for the same purpose! > >Also look in the Merck index where you will find turpentine. Turpentine is still around and so is "oil of turpentine" which is what you are referring to. Turpentine is really a gum from which the oil is distilled, but common usage often applies the single word to define either material. Jerry (Ico) DOC0331 Subject: Re: Immobilization of carbon dioxide From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/01 Message-ID: <4jo42l$e9t@geraldo.cc.utexas.edu> Newsgroups: sci.environment,sci.chem,sci.engr.chem In article <828294325snz@daflight.demon.co.uk>, Hugh Easton says: >The oceans contain >60 times as much CO2 as the atmosphere, and all mankind's emissions to >date amount to only about 1 percent of this. Do you happen to know what the theoretical equilibrium amounts of CO2 in the air and oceans would be if such a hypothetical equilibrium existed under current temperature conditions? How do these amounts compare with the actual distribution? Jerry (Ico) DOC0332 Subject: Re: Help with salt water density From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/04 Message-ID: <4jvs19$lie@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.engr.chem In article <4jv0ac$gbp@dfw-ixnews2.ix.netcom.com>, frontrec@ix.netcom.com(Sergio E Firpo) says: > >I would appreciate any help in determining the density of salt water >using different salts and different concentrations. > I know the density of sodium chloride (NaCl2) is 2.165 g/cm3 and the >solubility in water is 264 g/L. For Calcium Chloride the density is > 2.16 g/cm3 and the solubility is 427 g/L. Is this data suficient? I am >not sure if a direct sum of the fractions apply. > No, the volumes are not in any way reliably additive; the densities of solutions must be obtained experimentally. There are existing tables of densities for many different salt solutions. The older handbooks are more likely to contain this sort of data than are some of the newer ones. There are extensive tables in the chemical literature. Here are a few values for NaCl and CaCl2 solutions @ 20/4 C from the fourth edition of Lange's Handbook to give you an idea: %1 2% 4% 8% 12% 16% 20% NaCl 1.0053 1.0125 1.0268 1.0559 1.0857 1.1162 1.1478 CaCl2 1.0148 1.0316 1.0659 1.1015 1.1386 1.1775 Jerry (Ico) DOC0333 Subject: Re: What food holds the most heat? Potato? From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/06 Message-ID: <4k4uk8$odq@geraldo.cc.utexas.edu> Newsgroups: sci.chem,alt.sci.physics.plutonium,sci.bio.misc In article <4k48h3$hh3@dartvax.dartmouth.edu>, Archimedes.Plutonium@dartmouth.edu (Archimedes Plutonium) says: > >In article <1996Apr4.031250.24093@galileo.cc.rochester.edu> >gl002c@uhura.cc.rochester.edu (G. Lane) writes: > >> Water has one of the highest specific heat capicities, food that has a lot >> of water should retain a lot of heat. So tubers (including potatoes) should >> retain a lot of heat. >> george > > Thanks George, now I need to generalize that. So H20 as a polar >molecule has high specific heat capacity. > > What would be the concept of heat capacity for the elements 1 through >100? And what element in pure form would hold the record? Is it carbon >for I understand it has the highest melting point and is heat capacity >related to melting point. Archimedes, I am pleased to tell you that Carbon actually has a an exceptionally low (molar) heat capacity of about 2 kcal and diamond is even lower at less than 1.5. The reason for my pleasure is having the privilege of announcing that the highest heat capacity listed in my references appears to be enjoyed by non other than your favorite element, Plutonium. Said heat capacity is listed as 8.48 cal/mole. I suspect that sci.physics and sci.chem will be hearing more about this matter in the near future. Jerry (Ico) DOC0334 Subject: Re: high temp reactions From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/07 Message-ID: <4k7qbd$ncb@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article <4k6vd9$hnl@cronkite.seas.gwu.edu>, roxas@gwis2.circ.gwu.edu (Audrey Roxas) says: > > >Hello all! Just a quick question. > >Is it true that > >CaC O + Heat --> CaCO (s) + CO(g) > 2 4 3 > >and > >CaCO + Heat (circa 850 degrees C) --> CaO(s) + CO (g) > 3 2 > >Hope I don't sound too stupid. Later! > Nothing stupid about those questions. Calcium oxalate does decompose "with little charring" as written and the second reaction is the method of making lime (quicklime, not slaked lime) for such purposes as cement manufacture. Jerry (Ico) < DOC0335 Subject: Re: Help with salt water density From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/08 Message-ID: <4kc04a$iub@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.engr.chem In article <4kbo32$1r6m@service.polymtl.ca>, Roger Pelletier says: > >Is there an easy way to measure the density of salt solutions at >temperature below 0 C with 0.02 g/cm3 precision? It seams to me that it >would need costly equipments. > If that is all the accuracy you require for KCl solutions in the range -5 to 15 degC, why not simply assume that the density change is the same as it is for pure water? The maximum density change for water in this range occurs between 15 and 0 and amounts to only 0.0009 g/ml. There is only a 4% change from freezing to boiling. It seems logical to assume that you can calculate the density of a given solution as D(soln @t) = D(soln @ t0)*D(H2O @t)/D(H2O @t0), t0 = reference temp. I would be surprised if this calculation doesn't yield values well within your desired 2% precision (and accuracy). You can easily check out the validity of the method by either finding or measuring values for two or three temperatures above zero. BTW, the logistics of measuring densities at -5 C to an accuracy of 2% would require nothing more elaborate than a balance, a freezer, a couple of thermometers and some household items, if you have something to serve as a pycnometer or volumetric flask. For the limited accuracy you require, you could get a whole series of values (V vs t) from a single volumetric flask with the neck calibrated like a graduated cylinder. Just measure the volumes going down in temperature and then going up with good insulation around the body of the flask to slow the process down. Jerry (Ico) DOC0336 Subject: Re: Semi skimmed milk From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/08 Message-ID: <4kahuf$hnm@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Eric Lovett says: > >Dear All, > I have recently read that heating food can destroy flavour >components. > So when skimming milk, what side affects is caused to the milk. >(eg loss of nutrional, flavours etc) Skimming milk has nothing to do with heating. Butterfat, in the form of cream, rises to the top of unhomogenized milk on standing and can be literally skimmed off. You bet you lose flavour when you get rid of the fat, sigh. Jerry (Ico) DOC0337 Subject: Re: throwing boiling water into freezing air From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/10 Message-ID: <4kfm0c$gof@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Nancy McGough says: > >I'd like to understand the chemistry of the following. > > You throw a pan of boiling water into freezing air > and all the water vaporizes. > >Now, in order for it to vaporize it needs to absorb some >heat, but where is this heat coming from? Does this >only happen in freezing air? If so, why? > They lied to you. The water hits the ground, mostly unevaporated, and then gradually evaporates by drawing heat from both the air and the ground. We are assuming, of course, that you did not throw the water out of an airplane. Under such circimstances, it may well evaporate before it lands, deriving the necessary heat from the surrounding air. In either case, it helps if the air and/or ground is warm. They were supposed to tell you that the water freezes before it strikes the ground, which, again may be true if you toss it out of an airplane at low temperature or out of a space ship. Sigh, they pulled the wrong leg - no bells. Jerry (Ico) DOC0338 Subject: Singed Hair From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/12 Message-ID: <4kmbc9$31l@geraldo.cc.utexas.edu> Newsgroups: sci.chem When hair is exposed to flame or heat it undergoes changes including melting and shriveling, generally referred to as "singeing." Does anybody here know at what temperatures these phenomena occur? In an actual fire situation, soot with its various accompanying chemicals is produced. Do these substances lower the onset of visible changes in the the structure of hair, i.e., do they lower the temperature at which hair apparently undergoes physical changes associated with singeing? Jerry (Ico) DOC0339 Subject: SONIA DIDN'T DO IT. From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/21 Message-ID: Newsgroups: sci.chem,sci.chem.analytical,sci.physics,misc.legal,misc.legal.moderated Sonia climbed from the bedroom window of the burning house looking for Uncle Bill. The frantic woman did not find him in the yard and tried repeatedly to reenter the house to get him out. The lady from victim aid escorted her to the hospital and then the police force of the tiny West Texas town swooped down on her hospital room. The authorities leaped to the conclusion of arson within an hour of the fire. Forensic samples were sent to San Antonio's Bexar County labs for analysis and they returned a positive GC-MS analysis for gasoline on Uncle Bill's clothes. The lab's evidence supervisor at the time was the infamous Fred Zain, who was said to be responsible for the most egregious evidence tampering spree in history. The West Texas stone-faced jury heard enough facts and evidence to establish Sonia's innocence a dozen times over, but they gave their beloved District Attorney and neighbor the verdict and sentence he wanted. "Science" is still a holy cow in that remote village. Sonia got 99 years. Sonia is innocent. With luck, we may get a third trial and if we do, it will take all the ammunition that can be mustered to hammer home the fact that Sonia did not kill Uncle Bill. The case has a number of scientific issues that will call for clear reduction to show-and-tell for yet another jury who will be predisposed to believe that police labs do no err even when they fail to label their cans of evidence and have no chain of possession documents. If the defendent were O.J., the case would be thrown out on a dozen grounds, but this defendent is dirt poor. There are currently three experts (fire/explosion/chemistry) and a lawyer donating time to try to save Sonia. We could use some input from a skilled reader of GC/MS hydrocarbon spectra to help verify how the charts were fudged. The pathology in this case is abominable. Any layman could tell that Uncle Bill probably died before the fire, but laymen have no standing in the courts. The combustion properties of gasoline are a factor. The D.A.'s case depends on a hollywood vision of what happens when gasoline is poured on a sleeping person and ignited. This case needs the glare of the media to force the prosecution to present an honest case that would survive the scrutiny of well-trained scientists. There is a story here worthy of serious investigative reporting. The UseNet has the potential of helping to right a gross miscarriage of justice. Who can help Sonia? Sonia didn't do it. Jerry (Ico) < DOC0340 Subject: Re: SONIA DIDN'T DO IT. From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/26 Message-ID: <4lriqn$dq7@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.chem.analytical,sci.physics,misc.legal Article Segment 1 of 2 In article , MOrtch@Ualberta.ca (Mary Ortch) says: > >In article <4lq5ld$ci3@geraldo.cc.utexas.edu>, glhurst@onr.com (Gerald L. >Hurst) wrote: > >> In article <4lo2l5$o19@access1.digex.net>, rdadams@access1.digex.net >(Dick Adams) says: > >> >Gerald L. Hurst wrote: > >> Slither back into your hole, moron. This is a serious business, >> you lame-brained nincompoop. This woman's life is at stake and you >> feel you have to stick your snotty nose in and show us all how >> smart you think you are. > >Sure he was being snide, but how is this reply going to help your cause? >Please think before you reply. > Lady, you are less snide than he but just as useless. >> In the present case we are going to have to prove that the lady is >> innocent. This is going to take a lot of very skilled and unpaid >> work by a number of lawyers and technical people. > >Fine, but you posted a long (purple prose) piece that was utterly devoid >of any real content to evaluate. How are you going to get anyone on your >side unless you can show anything that could differentiate you from a host >of others who just want to get away with murder? > What I posted was an introduction to the story. The technical stuff is pretty meaningless unless it is explained in the context of the events surrounding the bits of forensic evidence which are acquired later. >> I have studied the records and testimony of the case for many weeks now >> and I continue to slowly piece together the reasons why the system >> blundered. I cannot help but wonder how often science runs amok and >> results in the conviction of innocent people via shaky forensics. > >How nice for you. Why not post some of this for public scrutiny? As a >suggestion, keep your posts short and to the point. If you have several >different analytical questions, they should be broken in to several >different posts. As for how often it happens, well it certainly happens >both ways, for example O.J. and David Milgaard. Nice for me? How stupid and insensitive can you be? I will make my posts as long or as short as I deem necessary. It is incredible how nitpickers like you and your buddy DICK love to post your useless and vacuous comments and suggestions. May you live long enough to find yourself in Sonia's position. You're damned right it happens both ways, dummy. Have you forgotten the principle that it is better to set the guilty free than imprison the innocent. I suppose you'll have to wait until it happens to you or yours to find out how welcome your worthless suggestions are. As far as the exchange of detailed information, that is already occurring 18 hours a day, but you and your ilk are not included. I'm sorry I wasted five minutes venting at your smug and sanctimonius attitude. It is technical people like you who are the problem. You think that forensic problems are simply a set of spectra that determine guilt or innocence. All over this country there are technicians sitting at their GC's injecting eluted samples without the faintest notion of the history of the material they are analyzing. The results will be sent to an insurance company or police prosecutor who has not the vaguest idea of the reliability of the analysis or what it means. For the cop who gets your report the phrase "Consistent with the presence of class II hydrocarbons" means they found gasoline (ASTM) or maybe it means they found kerosene (NFPA). You think you've got a lot of good advice to give about limiting technical posts to "just the scientific facts"? You've got another think coming little missy. In this game, you need to start with a good Ph.D. and then learn something about weaving your technical know-how into the complex webb of motive, social interaction and applied science. By "applied science" I do not mean that elementary work of poking needles into the GC or sipping coffee while you peruse peaks and make your subjective evaluations on the graphs the computer refuses to interpret. DOC0341 Subject: Re: SONIA DIDN'T DO IT. From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/26 Message-ID: <4lriqn$dq7@geraldo.cc.utexas.edu> Article Segment 2 of 2 Chemistry and physics in forensic investigation require analytical methods that have not been reduced to routines and above all these sciences have to operate within and interface with the real life environment. That is why the "purple prose" is necessary. You could spend the rest of your life successfully working only on the "technical" problems in Sonia's case and never help the woman one little bit. There are very, very few people on the net who have the experience and skill to help Sonia. I will simply have to put up with crap from you and DICK, et al until I find a few good men (or other women). Jerry (Ico) DOC0342 Subject: Re: SONIA DIDN'T DO IT. From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/26 Message-ID: <4lq5ld$ci3@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.chem.analytical,sci.physics,misc.legal In article <4lo2l5$o19@access1.digex.net>, rdadams@access1.digex.net (Dick Adams) says: > > >Gerald L. Hurst wrote: > >> Sonia climbed from the bedroom window of the burning house >> looking for Uncle Bill. The frantic woman did not find him >> in the yard and tried repeatedly to reenter the house to get >> him out. > >Please name independent third party witnesses to this behavior!! > Slither back into your hole, moron. This is a serious business, you lame-brained nincompoop. This woman's life is at stake and you feel you have to stick your snotty nose in and show us all how smart you think you are. For those of you in the two scientific forums, I hope to publish details of the forensic case in an ongoing series as we try to illuminate the various technical misconceptions and poor theories that led to the conviction. Anyone can comment on the net so it will be necessary to suffer the idiots like DICK. I appreciate the helpful correspondence I have already received from technical folk who have offered their real skills in such tasks as interpreting GC-MS spectra and the like. Sonia is a real person and she really is innocent of wrongdoing. Those among you who, like DICK, are good little true believers do not know that the authorities often make egregious errors in prosecution and that our ideal of being innocent until proven guilty is not always followed. Sonia is not an old friend. I reviewed her case as a favor to an attorney with whom I had previously worked on a civil case. After plowing through a thousand pages of testimony, lab reports, investigation reports and the like, I quite easily concluded that her Uncle's death was a not unexpected accident. Three other experienced fire investigators have looked at the material and concur. The D.A.'s theory may have sounded good to a jury, but it did not jibe with the simple physical rules that we chemists and physicists are used to watching matter and energy follow. Police investigation does not always employ scientific methods. There is a strong tendency for some enforcement organizations to accept their initial theories as laws and then procede to compress the facts into the theoretical mold. In the present case we are going to have to prove that the lady is innocent. This is going to take a lot of very skilled and unpaid work by a number of lawyers and technical people. Since we cannot swat the DICKS of the net like mosquitos, I am ready to concede early that most of the material I have gathered relating to this case will have to be sent to a a few intelligent people who may be able to offer some valuable insights. There will be no DICKS on the mailing list. I have studied the records and testimony of the case for many weeks now and I continue to slowly piece together the reasons why the system blundered. I cannot help but wonder how often science runs amok and results in the conviction of innocent people via shaky forensics. Jerry (Ico) < DOC0343 Subject: Re: SONIA DIDN'T DO IT. From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/29 Message-ID: <4m38hg$lcb@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.chem.analytical,sci.physics,misc.legal There has been a lot of clucking in this forum about my bluntness in dealing with various posters, mainly students, who have commented on such matters as the non-technical character of the "purple" prose of my initial post telling Sonia's story. I have received extensive criticism for the sarcastic dismissal of the majority of these posts. I would like to say that I regret insulting the critics, but the truth is that I do not. Sonia's story is a c grade pulp fiction tale that would bomb in a minute as a work of fiction, but unfortunately is not fiction but fact. For the most part our students (and, to be fair, others) have pointedly focused on what a nasty old man I am with my barbed and intemperate replies to their clever comments about what is wrong with my style or my attitude. It is unfortunate but necessarily true that there will be no public postings of any of the technical aspects of Sonia's case. It is the nature of such things that they must be circulated to a small and select group of people with particular skills, tenacity and determination. I will not elaborate on this subject, but the reasons will be obvious to those experienced in such matters. It is possible that I may be able make an exception in particular aspects of the case such as the description of the prosecution's theory of the mechanics of the alleged crime. It might be an interesting exercise to see how well chemists and physicists in these forums are able to reconcile that theory with known physical phenomena. I suppose the decision depends on the level of expected static. If it appears that I am impatient with the dilettante posters that is because it really is so. My comments to these posters are mild reflections of my real opinion. 99 percent of everything that transpires in these science forums is recreational fluff. It does not matter much if the high schoolers get their homework done by professor Jones or yet another theory of the cosmos is introduced, but Sonia's fate matters a great deal. If you have something to contribute, contact me by email. If you merely wish to show how very clever you are and what a terrific sense of humor you have, save it for discussions of relativity. I have zero fear that I will "chase away qualified scientists." If you have the stuff that is needed, no amount of my curmudgeonry will keep you away; if you don't, I hope it does. I wish to thank those few qualified folks who have contacted me by email and express my appreciation for the help you have offered. It is extremely gratifying to note that these posts have mostly been by people who do have high levels of expertise and have all been by people sincerely trying to help Sonia. Thanks again. The best advice I have received is not to reply at all to those who have nothing to offer. I'll follow that advice. Jerry (Ico) DOC0344 Subject: Re: SONIA DIDN'T DO IT. From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/29 Message-ID: <4m1gi2$hl7@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.chem.analytical,sci.physics,misc.legal In article <4luhbk$dmk@grivel.une.edu.au>, dbromage@metz.une.edu.au (David Bromage) says: > >Gerald L. Hurst (glhurst@onr.com) wrote: >>As far as the exchange of detailed information, that is already occurring >>18 hours a day, but you and your ilk are not included. I'm sorry I wasted >>five minutes venting at your smug and sanctimonius attitude. > >Maybe it's _your_ attitude that keeps respectable scientists away from you? > Now that IS funny. You are referring, I presume, to yourself, missy and DICK. Aren't you the little student who pointed out that gasoline burns? How will I possibly get by without the help of you three "respectable scientists"? Your comments about the courts will probably lead to head-bobbing assent from the technical academics and uproarious laughter from the legal forum. There is no way to to teach in school what you do not know. Jerry (Ico) DOC0345 Subject: Re: SONIA DIDN'T DO IT. From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/04/30 Message-ID: <4m5ns0$hnc@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.chem.analytical,sci.physics,misc.legal In article <4m50to$m28@rzsun02.rrz.uni-hamburg.de>, fc3a501@rzaixsrv1.uni-hamburg.de (Hauke Reddmann) says: > >Then give us DATA,DATA&DATA! (Was I redundant?) >Your first post was much too general for any >sensible scientific comment. Raid the court files, >append the forensic data, stuff us with 10M of >scenery gifs - eh, on second thought, don't -, >but give us !!!DATA!!! > Sorry HR, you're not paying attention. The first post was intended to be precisely what it was. No scientific comment was expected. DATA, DATA & DATA wouldn't do you the least bit of good. Like most, you have not the foggiest idea what is involved and what is required to tackle this type of problem. The "science" that you and I practice in the normal course of research is only an element in the analysis of a court case. If I showered you with chemical analyses and spectra from the case, you (or anyone else) would not be able reach any meaningful conclusions. The fact that the original "purple prose" story did not elicit a different sort of response is indication enough that you probably cannot be of help at this stage. It is quite possible that later on there may be some clearly defined "scientific" questions that will be right up your alley. Here is a general type of question which you or one of the other skilled scientists might like to have a bash at: Suppose that a fire burns in a room containing various common natural and synthetic materials such a PE, polyurethane, PVC, ABS, nylon, polyester, wood, coatings and the like and that the fire burnes long enough to create a lot of pyrolizates. A technician takes a sample of partially burned material from a location at which he suspects gasoline was poured to initiate the fire. He neglects to take any comparative samples from other locations in the room. The technician subjects the sample to purge-and-trap separation and collection in charcoal followed by elution and GC-MS analysis. The raw spectra show thousands of peaks which the computer sorts out into sub-spectra, trying to eliminate all not purely CH compounds, and it labels the subspectra as "naphthalenes," "alkyl benzenes," and the like but does not actually print out the mass numbers. Assume that the distribution of "hydrocarbons" and "alkanes" is substantially different from gasoline per se, containing a very much higher proportion of higher molecular weight materials. The technician decides from the visual interpretation of the sub-spectra that the sample contains some unknown brand of "thermally degraded gasoline." The question is what criteria can one apply to ascertain the credibility of such an interpretation in the absence of any specific parameters having been recorded by the technician to justify his conclusion. In a complex mixture of pyrolizates how does one quantify the reliability of such an analysis in the absence of control samples from the same general environment? Finally, is it acceptable at all to test a fire debris sample for suspected foreign accelerants in the absence of a control sample from the same or nearby environment? Jerry (Ico) DOC0346 Subject: Re: SONIA DIDN'T DO IT. From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/05/02 Message-ID: <4m9bqh$59u@geraldo.cc.utexas.edu> Newsgroups: sci.chem,sci.chem.analytical,sci.physics,misc.legal In article <4m32ed$ns@s-cwis.unomaha.edu>, stone@cwis.unomaha.edu (Travis Stone) says: > >Gerald L. Hurst (glhurst@onr.com) wrote: >[bitch-bitch-bitch-gripe-gripe-gripe] >> You think that forensic problems are >> simply a set of spectra that determine guilt or innocence. > >No....no more than most people think that lawyers are parasites who feed >off the miseries of other people and who habitually twist the facts to >get their clients off no matter what it takes, true as that may be. > Both propositions sound good to me. But what would be more useful would be if someone here has handy an approximate typical composition for untreated (no fire retardent) flexible polyurethane foam such as is routinely used in mattresses, furniture and the like. I'd like to calculate the approximate heat of combustion -- unless someone also has some equally handy thermodynamic data. Travis, I'm really sorry if I offended you. I had no idea you were a lawyer. Jerry (Ico) DOC0347 Subject: Re: Unka Al groupies From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/05/10 Message-ID: <4muo5t$cgk@geraldo.cc.utexas.edu> Newsgroups: sci.chem In article , Lev Gorenstein says: > >On Wed, 8 May 1996, Mark Tarka wrote: > >> Just in case this gets to the level of a free-speech issue...I >> demand the right to have unprotected internet-conversations with >> that no-good, rat-haired, anti-reality, scum o' the earth degenerate >> known as Al Schwuartis...whatever...Uncle Al. However, I do reserve >> the right to ammend this post, demanding that the said Uncle Al be >> executed (electronically speaking) forthwith (i.e. immediately). > > >I was always wondering, why the defenders of free speach are so eager to >execute everyone whose opinion differs from theirs? "We are for >democracy, so we'll lynch everybody, who's against it", right? How nice >of you, Mark Tarka. You HAVE the right to talk, but yet you'd like to >deny this right to Uncle Al, presenting this as "protection of a free >speach". YOUR speach. If you're so concerned about the freedom, why are >you jealous towards the freedom of others? I'm not even mentioning the >disgusting rude language you used. Would you please learn some manners?? > Lev, I think you may be taking Mark's words a little too seriously. Jerry (Ico) DOC0348 Subject: Re: Dangerous/Illegal Demonstrations From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/05/21 Message-ID: <4ntld1$7kr@geraldo.cc.utexas.edu> Newsgroups: rec.pyrotechnics,sci.chem,alt.engr.explosives,sci.engr.explosives In article <4nt440$jnq@mailhost.zeneca.co.uk>, Geoffrey Cooper says: > >Mike Herauf wrote: >>Carrying a gas mixture (I think H2 and Cl2) across a parking lot from the physics >>building to the chemistry building, a professor was preparing for the annual Chem. >>100 stoichiometry lesson. The balloon is usually set off with a flashbulb, showing >>its photoreactivity to a specific wavelength, previously not set off with a >>low-power laser of inappropriate frequency. However, this particularly bright day, >>the sunlight set it off while in transit and knocked him unconscious for a few >>seconds. >> >>I don't remember the gasses involved, would H2 and Cl2 do this? > >Mike, > Isn't it Cl2 and CH4 that make the classic photochemically initiated >reaction? Our instructor set it off (within an inverted graduated >cylinder immersed in water) with light from a burning strip of magnesium. > The reactions you two are talking about both depend on photoactivation of a chlorine molecule followed by a chain reaction. The reaction with hydrogen is the "classical" one, but the mechanism is essentially the same. The hydrogen-chlorine reaction is not one I would suggest relying on not to occur in the absence of a photon or two. Jerry (Ico) DOC0349 Subject: Re: Dangerous/Illegal Demonstrations From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/05/22 Message-ID: <4nvmh9$eo9@geraldo.cc.utexas.edu> Newsgroups: rec.pyrotechnics,sci.chem,alt.engr.explosives,sci.engr.explosives In article <4nv6ff$ljv@clorox.news.pilot.net>, Mike Herauf says: > >Geoffrey Cooper wrote: >>Mike Herauf wrote: >>>Carrying a gas mixture (I think H2 and Cl2) across a parking lot from the physics >>>building to the chemistry building, a professor was preparing for the annual Chem. >>>100 stoichiometry lesson. The balloon is usually set off with a flashbulb, showing >>>its photoreactivity to a specific wavelength, previously not set off with a >>>low-power laser of inappropriate frequency. However, this particularly bright day, >>>the sunlight set it off while in transit and knocked him unconscious for a few >>>seconds. >>> >>>I don't remember the gasses involved, would H2 and Cl2 do this? >> >>Mike, >> Isn't it Cl2 and CH4 that make the classic photochemically initiated >>reaction? Our instructor set it off (within an inverted graduated >>cylinder immersed in water) with light from a burning strip of magnesium. >> >>Geoff >> > >Very possibly. The exact reaction escapes me. What would the products of CH4 and Cl2 >be? > The mechanism of the H2-Cl2 reaction is: Cl2 + photon -> 2[Cl] [Cl] + H2 -> HCl + [H] [H] + Cl2 -> HCl + [Cl] The reaction with methane would follow a simiar form with the appropriate methyl or substituted methyl radicals. One might reasonably expect to get some of all the chlorine-substituted methane species, elemental carbon and ethane species with amounts depending on the ratio of starting materials and the concentration (pressure) of the mixture. The formation of HCl is the primary driving energy for the reaction as the C-Cl bond is relatively weak. Either of these two reactions would be somewhat quenched by surfaces, but the efficiency of quenching would be very low, especially for surfaces with a coat of water. Jerry (Ico) DOC0350 Subject: Re: Lifting capacity of helium From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/05/22 Message-ID: <4nvon6$eo9@geraldo.cc.utexas.edu> Newsgroups: rec.models.rc.misc,sci.chem,rec.models.rc.air In article <31A33271.4B113C13@MIT.EDU>, Christopher C Stratton says: > >A lot of people have been replying with numbers on the order of >25g/mole, but this assumes that the pressure inside the balloon >is the same as outside. Because the rubber is elastic, the pressure >inside will have to be greater, thus the density will be higher and >one will not get this much lift. I don't really know what >the reduction would be, but I could imagine it would be as much >as half. Also, this effect would tend to widen the gap in available >lift between hydrogen and helium. > >I think probably the best thing to do is just experiment. You >might get some idea from small rougly circular balloons, >but the effect may not be of the same maginitude with larger ones. >thus you probably won't know until you try it. > >It would be possible to inflate a large balloon with air, then >measure the pressure at the neck and figure out the density >inside from that. This should make it possible to calculate >the lift that would be available if the air were replaced >with helium. > The pressure inside a rubber balloon is not very high, in most cases. well below 1 psi. For RC work one would probably prefer a so-called "Mylar" (Sorry, duPont. Registered trademark) balloon in which the pressure may be set at zero if necessary. The rupture pressure of such a balloon large enough to carry an RC payload would be a fraction of a psi. For small balloons the primary correction for lift is the weight of the envelope. The envelope weight of an 18" (lay-flat) Mylar balloon is about 10 grams and the gross lift is only 13 grams (net = 3 grams). Larger balloons, of course, have lower envelope weight ratios. Rubber balloons are a lot lighter than the plastic ones but they lose helium much faster. Jerry (Ico) Jerry (Ico) DOC0351 Subject: SONIA DIDN'T DO IT From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/06/09 Message-ID: <4pdvs3$o5n@geraldo.cc.utexas.edu> Newsgroups: sci.chem The original articles posted on this subject were not favorably received in sci.chem so the thread will not be posted here. Fortunately, we have found the needed analytical chemistry expertise elsewhere. For those who are interested there is a new article in sci.med.cardiology and sci.med.pathology. Comments for my attention should be by e-mail. DOC0352 Subject: Coal tar solvent naphtha compositions From: glhurst@onr.com (Gerald L. Hurst) Date: 1996/11/03 Message-ID: <55j5li$oki@geraldo.cc.utexas.edu>> Newsgroups: sci.chem I was in the library last night looking for information on typical compositions of coal tar naphthas in the approximate boiling point range of gasoline. I am particularly interested in the distribution of C3 and C4-alkylbenzene species and indan derivitives and how it compares with typical gasoline or reformate compositions. Unfortunately, nearly all the references on coal tars are now in storage and not available for perusal by non-student, non-faculty chemists. I guess coal is no longer a hot topic in the schools :) Does anyone here have any such data on typical compositions or perhaps some chromatograms or pointers to such information? I would like to compare the apparent relative abundance of the various isomers. Most of the literature so far within my reach gives some data for benzene, xylene isomers, naphthalene and methyl naphthalenes but refers to the inbetween stuff merely as "naphtha." I am also interested in any studies of the pyrolysis products of other organic materials such as wood or plastic which yield aromatic species such as those mentioned above. I would like to compare the distribution of species in such products with those of the better characterized Friedel-Crafts alkylations and disproportionation reactions. Thanks, Jerry DOC0353 Subject: Re: Lye/Aluminum reactor? From: glhurst@onr.com (Gerald L. Hurst) Date: 1997/02/14 Message-ID: <5e16j5$fa0@geraldo.cc.utexas.edu> Newsgroups: rec.pyrotechnics,sci.chem,alt.engr.explosives In article <5e11vv$6v4@crl13.crl.com>, gherbert@crl.com (George Herbert) says: > >You can use water as fuel with ClF5 oxidizer, but nobody does... hydrazine >is much higher specific impulse. There is a ClF5-hyd motor and associated >upper stage that were recently developed by the DOD for high performance >transfer stage usage. > It is good to hear that the early work on ClF5 has born some fruit. I designed, built and managed the Aerojet-General pilot plant which churned out 8,000 lbs of ClF5 for experimental purposes back in 1966. In those days, ClF5 was unknown in the open literature. Perhaps the happiest day of my life was the day the program was completed and I was finally able to shut down that monster plant which had been running around the clock in a perpetual fog of evaporating liquid nitrogen. It seemed that whenever the plant blew, there was rain to ignite the ClF5 gas escaping from the various ruptured high and low pressure lines. The dripping cold liquid also put on a pretty pyrotechnic display as it burst into white flame on contact with the concrete plant floor. As a reward for working 20 hours a day, seven days a week for months the division V.P. offered me a sincere apology for the tiny Christmas bonus (based solely on a low seniority level). As a consolation prize I was given a standing ovation (attaboy with clapping) by the fully assembled Aerojet V.P.s and handed an extra week's vacation. Later, the V.P. of my division said to me, "You B******, you used that week to find another job." He was right. I got a super raise and a night of unlimited banana cows by joining the new Explosives Corporation of America (EXCOA) as their Chief Scientist. Working with ultra-sensitive explosives was like a vacation after dodging hot ClF5 at at obscene pressures. Despite my abrupt departure from Aerojet, I really did like that company and I understood that the boss' hands were tied by inflexible company policy. After all, I had volunteered to take over the then unproductive plant after being forewarned by the previous manager (a once sane PhD engineer) whom I met babbling to himself in the hallway about needing an exorcist. Besides, I learned the valuable lesson that no good deed goes unrewarded at best or unpunished at worst :) Frankly, I miss those early days of both the aerospace race and the entrepeunerial explosives research nurtured by the Viet Nam problems. Both of these situations created incredible R&D environments where the only limitation was the imagination. In those days science was actually a respected occupation. Don't get me wrong though. I wouldn't do it again for any amount of money. It took an undeserved lot of pure luck to survive the learning curve. Jerry (Ico)