Formula Mole Weight Critical Pressure Critical Temperature
C2H2 26.04 890.6 psia 95.3 F


General Description:

The hydrocarbon class of alkynes includes those with carbon-carbon triple bonds. Such molecules are very unstable, thus few naturally occurring alkynes exist outside the laboratory. The smallest of the alkynes, acetylene, is used in melting and welding iron and steel. Other synthetic alkynes are commonly used in drugs or medication.

Keeping in mind that every carbon prefers 4 bonds, the chemical formula for acetylene has 2 carbons and 2 hydrogens. That tells us that each carbon is attached to one hydrogen, leaving three bonds left for the carbon atoms. Thus, acetylene is the common name for ethyne, which is an alkyne, or an organic molecule with a triple bonded carbon.

Pressure, psia 14.7 100 500
Temperature, F 60 200 300
Compressibility, (Z) 0.993 0.979 0.937
Enthalpy, Btu/lb (h)  155.5 211.5 247.3
Entropy, Btu/lb-R (s) 1.395 1.346 1.278
Specific Heat, Btu/mol-R(Cp) 0.398 0.456 0.516
k, (Cp/Cv)  1.237 1.201 1.174
Sonic velocity, ft/sec 1105 1217 1266
Specific volume, ft3/lb 14.5 2.66 0.586
Dynamic viscosity, lb/ft-sec 6.544E-06 8.18E-06 9.972E-06



1) Gas Flex, Flexware, Inc., Grapeville, PA, USA
2) Organic Chemistry, Paula Yurkanis Bruice, University of California, Prentice Hall, NJ, 1998
3) General Chemistry, Darrell D. Ebbing, Wayne State University, Houghton Mifflin Co., 1996

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Flexware, Inc. 2005
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page updated May 21, 2005