A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.
(1) What is the initial effect of the change on vapour pressure?
(2) How do rates of evaporation & condensation change initially?
(3) What happens when equilibrium is restored finally and what will be the final vapour pressure?

Explanation

Equilibrium: `H_(2)O (l) hArr H_(2)O(g)`
(1) Increasing the volume of the container at contant temperature reduces the vapour pressure.
(1) Increasing the volume of the container at constant temperature reduces the vapour pressure.
(2) According to Le chatelier's principle, the increase in volume of the system at constant temperature increases the rate of evaporation compared with that of the rate of condensation.
(3) When equilibrium is restored, the rates of evaporation and condensation because equal. at new equilibrium, vapour pressure will be the same as that of original equilibrium as vapour pressure of a liquid is an intensive property which is independent of the size of the system.