Question

Show that the depression of freezing point is a colligative property.

Answer 1

The depression of freezing point is given by

ΔT_f = K_f . m

Where,

K_f = cryoscopic constant 

m = molality of solution

`m = (n_"solute")/"mass of solvent in kg"`

The molality m is a measure of the number of moles of solute, not its chemical nature.

ΔT_f​ thus depends only on the quantity (not type) of solute particles.

ΔT_f​ ∝ Number of Solute Particles and not on their chemical identity, the depression of freezing point is indeed a colligative property.