question_answer

  Define vapour pressure. What happens to the vapour pressure when (i) volatile solute dissolves in the liquid, (ii) non-volatile solute dissolves in the liquid.

Answer:

  The pressure exerted by gas molecules on its liquid layer at equilibrium is called vapour pressure. (i) When volatile liquid is added to another liquid then the resultant vapour pressure may increase, decrease or may remain same depending on the strength of solute- solvent interaction. (ii) Net vapour pressure decreases when non-volatile solute is added to it.