Question

0.1 M urea solution shows less depression in freezing point than 0.1 M MgCl₂ solution. Explain.

Answer 1

A 0.1 M urea solution shows less depression in freezing point than 0.1 M MgCl₂ solution because urea is a non-electrolyte and does not dissociate in water, whereas MgCl₂ is an electrolyte and dissociates into 3 ions (Mg²⁺ + 2Cl⁻).

Freezing point depression is a colligative property and depends on the number of solute particles in solution.

Urea → i = 1

MgCl₂ → i = 3

Thus, MgCl₂ produces more particles, causing greater depression in freezing point than urea.