Question

In the case of real gases, the equation of state, $\mathrm{PV}=\mathrm{RT}$ (where $\mathrm{P},\mathrm{V}\mathrm{and}\mathrm{T}$are respectively the pressure, volume and absolute temperature), is strictly satisfied only if corrections are applied to the measured pressure $\mathrm{P}$ and the measured volume $\mathrm{V}$. When does the corrections for $\mathrm{P}$ and $\mathrm{V}$ arise?

Answer 1

Corrections for $\mathrm{P}$ arise in the case of real gas:

• According to the kinetic theory of gases, it is assumed that there is no force between molecules. But in the case of real gases, there is indeed an intermolecular attraction, which reduces the pressure.
• Thus here, for real gases correction for $\mathrm{P}$ arises due to intermolecular attraction.

Corrections $\mathrm{V}$ arise in the case of real gas:

• The assumption made by the gases of kinetic theory, that molecules are point masses without appreciable volume is not correct as in the case of real gases the entire volume $\mathrm{V}$ of the container is not available for the molecules since the molecules have a finite size.
• Hence, here for real gases, the correction for $\mathrm{V}$ arises due to the size of molecules.

Hence, In the case of real gases, the corrections for $\mathrm{P}$ arise due to intermolecular attraction and $\mathrm{V}$ arises due to the size of molecules.