At standard temperature and pressure (STP), which is defined as 0°C (273.15 K) and 1 atm (101.325 kPa), the molar volume of hydrogen (H2) is approximately 22.4 liters per mole (L/mol).

This means that under STP conditions, one mole of hydrogen gas occupies a volume of 22.4 liters. The molar volume of a gas is a fundamental property that is related to the temperature, pressure, and amount of substance of the gas.

At STP, the molar volume of hydrogen is the same for all hydrogen gas samples, regardless of their purity or the presence of other gases. This is because the molar volume of a gas is a measure of the volume occupied by one mole of that gas under specific conditions of temperature and pressure.

The molar volume of hydrogen at STP can be used to calculate the volume of hydrogen gas required for a given number of moles or the number of moles of hydrogen gas present in a given volume. It is also useful for comparing the molar volumes of different gases under the same conditions of temperature and pressure.