Question

Why does the boiling point of a liquid get elevated when a non-volatile solute is dissolved in it?

Answer 1

1. The boiling point of a liquid gets elevated when a non-volatile solute is dissolved in it because the vapour pressure of the solution decreases.
2. Boiling occurs when the vapour pressure of the liquid equals the external atmospheric pressure.
3. When a non-volatile solute is added, it lowers the vapour pressure by reducing the number of solvent molecules at the surface that can escape into the vapour phase.
4. As a result, a higher temperature is required to make the vapour pressure equal to the atmospheric pressure, leading to an elevation in boiling point.
5. This phenomenon is called boiling point elevation, a colligative property that depends on the number of solute particles, not their nature.