Molar Volume Formula

What is Molar Volume?

At standard Temperature and Pressure (STP) the molar volume (Vm) is the volume occupied by one mole of a chemical element or a chemical compound. It can be calculated by dividing the molar mass (M) by mass density (ρ). Molar gas volume is one mole of any gas at a specific temperature and pressure has a fixed volume.

Molar Volume Formula

The Molar volume is directly proportional to molar mass and inversely proportional to density. The formula of the molar volume is expressed as

\(V_{m} = \frac{Molar\ mass}{Density}\)

Where Vm is the volume of the substance.

The standard temperature used is 273 Kelvin or 0oC,

Standard pressure is 1 atmosphere, i.e., 760 mm Hg.

Experimentally, one mole of any gas occupies a volume of 22.4 litres at STP. The equation can be expressed as

1 mole of gas at STP = 22.4 litres of gas.

Example 1

Calculate molar volume for a sample of the molar mass of the Nif the density of the gas is 1.250 g/L?


\(V_{m} = \frac{Molar\ mass}{Density}\)

The molar mass of Nitrogen = 28.01 g/mol

Vm = (28.01)/(1.250)

Vm = 22.408 L

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