Molar Volume of Gas

It is also defined as the volume occupied by 1 mole of ideal gas under certain condition of temperature and pressure. These conditions can either be standard temperature and pressure (STP) or room temperature and pressure.

This volume is actually derived from the universal gas law:

PV = nRT

P	= the absolute pressure of the gas, in Pa
n	= amount of substance, in mol
V	= the volume of the gas, in m3
T	= the absolute temperature of the gas, in K
R	= the universal gas law constant of 8.3145 m3·Pa/(mol·K)

The unit for molar volume of gas is: V/n = litre

• V/n = 8.3145 × 273.15 / 101.325 = 22.414 m³/kmol at 0 °C and 101.325 kPa (STP)
  
• V/n = 8.3145 × 298.15 / 101.325 = 24.466 m³/kmol at 25 °C and 101.325 kPa (room temperature and pressure)