show that relative lowering in vapour pressure is equal to mole fraction of solute
Dear student,
When a non volatile solute is added to a solvent, the vapour pressure of the solution decreases. Let xA be the mole fraction of the solvent, xB be the mole fraction of the solute and pA^o be the vapour pressure of the pure solvent and p be the vapour pressure of the solution.
Since solute is non volatile, there will be no contribution of the solute to the vapour pressure and the vapour pressure of the solution will only be due to the solvent. Therefore, the vapour pressure of the solution p will be equal to the vapour pressure of the solvent pA, over the solution.
When a non volatile solute is added to a solvent, the vapour pressure of the solution decreases. Let xA be the mole fraction of the solvent, xB be the mole fraction of the solute and pA^o be the vapour pressure of the pure solvent and p be the vapour pressure of the solution.
Since solute is non volatile, there will be no contribution of the solute to the vapour pressure and the vapour pressure of the solution will only be due to the solvent. Therefore, the vapour pressure of the solution p will be equal to the vapour pressure of the solvent pA, over the solution.
