# Formula Definition of the Specific Gas Constant Molar mass

## Specific gas constant

Unit
The specific gas constant indicates the ratio of the molar gas constant to the molar mass of a gas.

GasSpecific gas constant $$R_{\text s}$$
Helium (He)$$2077.1 \, \frac{\mathrm J}{ \mathrm{kg}\, \mathrm{K} }$$
Methane (CH4)$$518.4 \, \frac{\mathrm J}{ \mathrm{kg}\, \mathrm{K} }$$
Nitrogen (N2)$$296.8 \, \frac{\mathrm J}{ \mathrm{kg}\, \mathrm{K} }$$
Oxygen (O2)$$259.8 \, \frac{\mathrm J}{ \mathrm{kg}\, \mathrm{K} }$$
Carbon dioxide (CO2)$$188.9 \, \frac{\mathrm J}{ \mathrm{kg}\, \mathrm{K} }$$

## Molar mass

Unit
Molar mass [kg / mol] of a substance is the total mass $$m$$ of the gas per amount of substance $$n$$: $$M_{\text n} = m/n$$.

GasMolar mass $$M_{\text n}$$
Helium (He)$$4.003 \cdot 10^{-3} \, \frac{\mathrm{kg}}{ \mathrm{mol}}$$
Methane (CH4)$$16.04 \cdot 10^{-3} \, \frac{\mathrm{kg}}{ \mathrm{mol}}$$
Nitrogen (N2)$$28.01 \cdot 10^{-3} \, \frac{\mathrm{kg}}{ \mathrm{mol}}$$
Oxygen (O2)$$32.00 \cdot 10^{-3} \, \frac{\mathrm{kg}}{ \mathrm{mol}}$$
Carbon dioxide (CO2)$$44.01 \cdot 10^{-3} \, \frac{\mathrm{kg}}{ \mathrm{mol}}$$

## Gas constant

Unit
Molar gas constant (also called universal gas constant) is a physical constant from thermodynamics and has the following exact value:$$R ~=~ 8.314 \, 462 \, 618 \, 153 \, 24 \, \frac{\mathrm J}{\mathrm{mol} \, \mathrm{K}}$$