Question

Why do real gases show deviation from ideal behaviour?

Answer 1

The causes of deviations from ideal behaviour may be due to the following two assumptions of kinetic theory of gases.

The volume occupied by gas molecules is negligibly small as compared to the volume occupied by the gas.The forces of attraction between gas molecules are negligible.

Answer 2

Causes

1. one of the posulates of kinetic molecular theory of gasses is there are no attractive or repulsive forces among gas molecules.

this statement is not true, under high pressure and low temprature because, under these conditions the volume of gas is very very small and the distance between the molecules are also very small, as a result intermolecular forces develope which cannot be neglected. because of these intermolecular forces, the observed pressure is always smaller than that of ideal gas

2. One of the posulates of kinetic molecular theory of gasses is, the actual volume occupied by gas molecules is negligible when compared to the total volume of the gas. This statement is not true at higher pressure and lower temprature because at these conditions, the volume of gas is extremely small.