Carbon dioxide melting point

Ordinary ice (solid water) melts at 0 °C, whereas dry ice (solid carbon dioxide) melts at a much lower temperature. Explain the differences in the melting points of these two substances on the basis of the intermolecular forces involved. 

Another indication of the probable incorrectness of the pressure melting explanation is that the variation of the coefficient of friction with temperature for ice is much the same for other solids, such as solid krypton and carbon dioxide [16] and benzophenone and nitrobenzene [4]. In these cases the density of the solid is greater than that of the liquid, so the drop in as the melting point is approached cannot be due to pressure melting. 

When cyciobutane 1 1 dicarboxylic acid is heated above its melting point until the evolution of carbon dioxide ceases, cycZobutanecarboxyllc acid (III) is formed in good yield ... 

Compounds that readily undergo thermal decarboxylation include those related to malonic acid On being heated above its melting point malonic acid is converted to acetic acid and carbon dioxide... 

Ammonium bicarbonate, also known as ammonium hydrogen carbonate or ammonium acid carbonate, is easily formed. However, it decomposes below its melting point, dissociating into ammonia, carbon dioxide, and water. If this process is carefully controlled, these compounds condense to reform ammonium bicarbonate. The vapor pressures of dry ammonium bicarbonate are shown below (7). (To convert kPa to mm Hg, multiply by 7.5.)... 

Fire Hazards - Flash Point (deg. F) 117 CC Flammable Limits in Air (%) No data Fire Extinguishing Agents Foam, carbon dioxide, dry chemical Fire Extinguishing Agents Not To Be Used Not pertinent Special Hazards of Combustion Products Not pertinent Behavior in Fire The solid often evaporates without first melting Ignition Temperature (deg. F) 466 Electrical Hazard Not pertinent Burning Rate No data. 

In 1897, Reissert reported the synthesis of a variety of substituted indoles from o-nitrotoluene derivatives. Condensation of o-nitrotoluene (5) with diethyl oxalate (2) in the presense of sodium ethoxide afforded ethyl o-nitrophenylpyruvate (6). After hydrolysis of the ester, the free acid, o-nitrophenylpyruvic acid (7), was reduced with zinc in acetic acid to the intermediate, o-aminophenylpyruvic acid (8), which underwent cyclization with loss of water under the conditions of reduction to furnish the indole-2-carboxylic acid (9). When the indole-2-carboxylic acid (9) was heated above its melting point, carbon dioxide was evolved with concomitant formation of the indole (10). 

The first synthesis of cinnoline was reported by von Richter in 1883. The diazonium chloride 5 which was obtained from o-aminophenylpropiolic acid (4), was heated in water at 70°C to provide the 4-hydroxycinnoline-3-carboxylic acid (6). When this acid 6 was heated above its melting point, carbon dioxide was liberated and 4-hydroxycinnoline (7) was obtained. Distillation of 4-hydroxycinnoline (7) with zinc dust furnished a small amount of oil, which was assumed to be cinnoline (8). The preparation of 4-hydroxycinnoline (7) was repeated by Busch and Klett, although in lower yield when compared to the original report. Busch and Rast later converted the 4-hydroxycinnoline (7) successfully to cinnoline (8) via the 4-chlorocinnoline (9). ... 

About 3 grams of 0-methylcholine chloride are stirred at room temperature with an excess of phosgene dissolved in 50 grams of chloroform, for about 2 hours. Excess phosgene and hydrochloric acid are removed by distillation under vacuo. Additional chloroform is added to the Syrup and the mixture is poured into excess ammonia dissolved in chloroform and cooled in solid carbon dioxide-acetone. The solid is filtered and extracted with hot absolute alcohol. The solid in the alcohol is precipitated with ether, filtered, and recrystallized from isopropanol. The carbaminoyl-0-methylcholine chloride obtained has a melting point of about 220°C. 

Iodine sublimes more readily than ice because its triple-point pressure, 90 mm Hg, is much higher. Sublimation occurs on heating (Figure 9.6) below the triple-point temperature, 114°C. If the triple point is exceeded, the solid melts. Solid carbon dioxide (dry ice) has a triple-point pressure above 1 atm (5.2 atm at — 57°C). Liquid carbon dioxide cannot exist at 1 atm pressure regardless of temperature. Solid C02 always passes directly to vapor if allowed to warm up in an open cantainer. 

The change of melting-point can produce a very marked alteration of v (e.g., carbon and carbon dioxide). Koref calculates the v values for a number of compounds, and the molecular heats thence obtained agree with the experimental values moderately well. 

Oxalic acid is relatively stable by itself it decomposes at a temperature starting at its melting point, which corresponds to 189.5°C, forming carbon dioxide, monoxide, formic acid and water. 

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