Specific heat ratio of common gases


Incl isentropic coefficient of air, ammonia, natural gas, water vapor

Gas Isentropic coefficient
Specific heat ratio
at 15 degrees celcius
Acetylene 1.24
Air 1.40
Ammonia 1.31
Benzene 1.12
Carbon dioxide 1.30
Carbon monoxide 1.40
Chlorine 1.36
Ethane 1.19
Ethyle Alcohol 1.13
Ethyle Chloride 1.19
Ethylene 1.24
Hydrogene 1.41
Methane 1.31
Methyl Alcohol 1.20
Methyl Chloride 1.20
Natural Gas 1.27
Nitrogen 1.40
Oxygen 1.40
Propane 1.13
Propylene 1.15
Water vapor 1.33

Source : Chemical Engineering, 1974