The molar volume of gas at STP is a fixed value of 22.4 liters per mole. This is the case for any type of gas.
Molar volume is calculated by dividing the molar mass of a gas by the density of the gas at STP. According to the British Columbia Institute of Technology, this ratio calculates to 22.4 liters per mole for any gas, whether it be nitrogen, oxygen, methane, carbon dioxide, hydrogen or argon. The calculation is made by dividing the molar mass, in units of grams per mole, by the density at STP, in units of grams per liter. This results in the unit of liters per mole.