# Specific gas constant

The specific gas constant of a gas or a mixture of gases is given by the molar gas constant divided by the molar mass $M_{gas}$ of the gas or mixture.

Another important relationship comes from thermodynamics. Mayer's relation relates the specific gas constant to the specific heat capacity at constant pressure minus the specific heat capacity at constant volume ($c_p-c_v$).

Values are taken from the engineering toolbox .

Symbol
$R_{gas}$
Unit
J/(kg.K)
Formulae
$\frac{1000R_{gas0}}{M_{mol}}$
Related
$M_{mol}$
Molar mass [g/mol]
Used in
$c_{p,gas}$
$c_{v,gas}$
$p_{gas}$
$\rho_{gas}$
Gas density [kg/m$^3$]
Choices
GasFormulaRgas
Air78%N2+21%O2+minor287.05
N2N2296.8
SF6SF656.93
CO2CO2188.92
COCO296.84
O2O2259.84
H2H24124.2
NH3NH3488.21
SO2SO2129.78
HeHe2077.1
ArAr208.13
KrKr99.22
XeXe63.33
NeNe412.02