Question

Write modification of expressions of colligative properties with the help of van't Hoff factor.

Answer 1

The modified expressions of colligative properties with the help of van’t Hoff factor i are as follows:

(1) By Raoult’s law: For vapour pressure lowering.

`(P^0 - P)/P^0 = ix_2   "OR"  (P^0 - P)/P^0  = i xx (W_2 xx M_1)/(W_1 xx  M_2)`

(2) For elevation in boiling point:

Δ T_b = i × K_b × m

`Δ T_b = i × K_b × (W_2 xx 100)/(W_1 xx  M_2)`

`Δ T_b = i × K_b × W_2/(W_1 xx  M_2)`

(3) For depression in freezing point:

Δ T_r = i × K_r × m

`Δ T_r = i × K_r × (W_2 xx 100)/(W_1 xx  M_2)`

`Δ T_r = i × K_r × W_2/(W_1 xx  M_2)`

(4) Osmotic pressure:

π = iCRT

`π = i xx (nRT)/V`

`π = i xx (WRT)/(M xx V)`