Question
What is the significance of the Vander Waal's constants? Write its units for Vander Waal's constants.
Solution
Vander Waal's equation of state for n moles of the gas is
The significance of constant 'a'. The value of constant a gives the idea of the magnitude of attractive forces between the molecules of the gas. Larger the value of a the larger will be the intermolecular forces between the molecules. Units of a. Pressure correction (β) is given by
The significance of constant 'b'. The constant b is called co-volume or excluded volume per mole of a gas. It is a measure of the effective size of gas molecules.
Units of b. Units of b must be units of volume i.e. L mol–1 or dm3 mol–1.
