SPECIFIC HEAT CAPACITY AND GAS CONSTANT TABLE FOR IDEAL GASES


Specific heats and gas constants of ideal gases including steam, air, argon and nitrogen are given in the following table. Here

  • R is gas constant and the unit is kJ/kg-K,
  • Cp0 is ideal-gas specific heats, or zero-pressure specific heats at constant pressure and the unit is kJ/kg-K,
  • Cv0 is ideal-gas specific heats, or zero-pressure specific heats at constant volume and the unit is kJ/kg-K.

Ideal gas is defined as a gas whose temperature, pressure, and specific volume are related by Pv = RT.  The usage of the ideal-gas specific heat table is limited to low pressure levels or moderately high pressures where gas does not deviate from ideal-gas behavior remarkably.

Specific Heat Values for Various Ideal Gases at 25 °C, 100 kPa **
Gas Chemical
Formula
R (kJ/kg-K) Cp0 (kJ/kg-K) Cv0 (kJ/kg-K)
Steam H2O 0.4615 1.872 1.410
Acetylene C2H2 0.3193 1.699 1.380
Air -- 0.287 1.004 0.717
Ammonia NH3 0.4882 2.130 1.642
Argon Ar 0.2081 0.520 0.312
Butane C4H10 0.1430 1.716 1.573
Carbon monoxide CO 0.1889 1.041 0.744
Carbon dioxide CO2 0.2968 0.842 0.653
Ethane C2H6 0.2765 1.766 1.490
Ethanol C2H5OH 0.1805 1.427 1.246
Ethylene C2H4 0.2964 1.548 1.252
Helium He 2.0771 5.193 3.116
Hydrogen H2 4.1243 14.209 1.008
Methane CH4 0.5183 2.254 1.736
Methanol CH3OH 0.2595 1.405 1.146
Neon Ne 0.4120 1.03 0.618
Nitric oxide NO 0.2771 0.993 0.716
Nitrogen N2 0.2968 1.042 0.745
Nitrous oxide N2O 0.1889 0.879 0.690
n-octane C8H18 0.07279 1.711 1.638
Oxygen O2 0.2598 0.922 0.662
Propane C3H8 0.1886 1.679 1.490
R-12 CCL2F2 0.06876 0.616 0.547
R-22 CHCLF2 0.09616 0.658 0.562
R-134a CF3CH2F 0.08149 0.852 0.771
Sulfur dioxide SO2 0.1298 0.624 0.494
Sulfur trioxide SO3 0.10386 0.635 0.531

Note: ** Or saturation pressure if it is less than 100 kPa.

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