ACETYLENE.
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Written by tom
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Friday, 29 February 2008 |
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A colorless gas of the composition HC:CH, used for welding and flame cutting of metals, and for producing other chemicals. It contains 92.3% carbon, and is therefore nearly gaseous carbon. When pure, it has a sweet odor, but when it contains hydrogen sulfide as an impurity, it has a disagreeable odor.
Acetylene burns brightly in the air, and was widely used for theater stage lighting before the advent of the electric light. When mixed with oxygen as oxyacetylene for flame cutting and welding, it gives a temperature of 3500°C. In air it is an explosive gas. The maximum explosive effect is with a mixture of 7.7% gas and 92.3% air. Acetylene has a specific gravity of 0.92. It is nontoxic, and is soluble in water, alcohol, or acetone. It liquefies under a pressure of 700 lb/in2 (5MPa) at 70°F (21°C). It is easily generated by the action of water on calcium carbide, but is also produced from petroleum. It is marketed compressed in cylinders, dissolved in acetone to make it nonexplosive. One volume of acetone will dissolve 25 volumes of acetylene at atmospheric pressure, or 250 volumes at 10 atm (10.3 kg/cm2). Prest-O- Lite is a trade name of Union Carbide Corp. for acetylene dissolved in acetone. Acetylene snow, or solid acetylene, is produced by cooling acetylene below the melting point and compressing. It is insensible to shock and flame, and is thus easier to transport. A replacement for acetylene for producing plastics is methyl acetylene propadiene, which contains 70% methyl acetylene and 30 of the isomer propadiene. It has the reactions of both acetylene and its isomer. Mapp, of the Dow Chemical Co., for metal cutting is methyl acetylene, CH:C·CH3. It is safer to handle and gives about the same flame temperature
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Last Updated ( Saturday, 01 March 2008 )
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