Properties of Various Ideal Gases (at 300 K)
Gas Formula Molar Mass Gas constant Specific Heat
at Const. Press.		 Specific Heat
at Const. Vol.		 Specific Heat
Ratio

M[kg/kmol]

R[kJ/kg.K]

Cp[kJ/kg.K]

Cv[kJ/kg.K]

k = Cp/Cv
Air

--

28.97

0.287

1.005

0.718

1.4
Argon

Ar

39.948

0.2081

0.5203

0.3122

1.667
Butane

C4H10

58.124

0.1433

1.7164

1.5734

1.091
Carbon Dioxide

CO2

44.01

0.1889

0.846

0.657

1.289
Carbon Monoxide

CO

28.011

0.2968

1.04

0.744

1.4
Ethane

C2H6

30.07

0.2765

1.7662

1.4897

1.186
Ethylene

C2H4

28.054

0.2964

1.5482

1.2518

1.237
Helium

He

4.003

2.0769

5.1926

3.1156

1.667
Hydrogen

H2

2.016

4.124

14.307

10.183

1.405
Methane

CH4

16.043

0.5182

2.2537

1.7354

1.299
Neon

Ne

20.183

0.4119

1.0299

0.6179

1.667
Nitrogen

N2

28.013

0.2968

1.039

0.743

1.4
Octane

C8H18

114.231

0.0729

1.7113

1.6385

1.044
Oxygen

O2

31.999

0.2598

0.918

0.658

1.395
Propane

C3H8

44.097

0.1885

1.6794

1.4909

1.126
Steam

H2O

18.015

0.4615

1.8723

1.4108

1.327

Adapted from TEST (The Expert System for Thermodynamics) <www.thermofluids.net> by S.Bhattacharjee, San Diego State University