Question

A cylinder fitted with an air tight piston contains a small amount of a liquid at a fixed temperature. The piston is moved out so that the volume increases
(a) What will be the effect on the change of vapour pressure initially?
(b) How will the rates of evaporation and condensation change initially?
(c) What will happen when equilibrium is restored finally and what will be the final vapour pressure?

Answer 1

(a) If the vol of the container is suddenly increased, them

the vapour pressure would decrees initially Therefore

Same amount of vapour is distributed in a large volume

(b) at constant temperature, rate of evaporation is constant

and rate of condensation decrees initially

(c) When the equilibrium is restored finally;

rate of evaporation $=$ rate of condensation

and final vapour pressure $=$ original vapour

pressure of system.