Explain the vapour pressure of solutions of solids in liquids.

(N/A) Liquids at a given temperature vaporize,and under equilibrium conditions,the pressure exerted by the vapours of the liquid over the liquid phase is called vapour pressure.
In a pure liquid,the entire surface is occupied by the molecules of the liquid. If a non-volatile solute is added to a solvent to form a solution,the vapour pressure of the solution is solely due to the solvent molecules.
This vapour pressure of the solution at a given temperature is found to be lower than the vapour pressure of the pure solvent at the same temperature. In the solution,the surface contains both solute and solvent molecules; thereby,the fraction of the surface covered by the solvent molecules is reduced. Consequently,the number of solvent molecules escaping from the surface is correspondingly reduced,thus,the vapour pressure is also reduced.