Question

The elevation in boiling point of $0.25$ molal aqueous solution of a substance is $(K_b = 0.52\, K\, kg\, mol^{-1})$

• A. $0.15 \,K$
• B. $0.50 \,K$
• C. $0.13 \,K$
• D. $2.08 \,K$

Answer 1

Answer: (C)

$0.13 \,K$

Answer 2

Key Idea Elevation in boiling is directly proportional to molal concentration of solute in
a solution $\Delta T_{b} \propto m, \Delta T_{b}=K_{b} m$

Given,

$m=0.25$
$K_{b}=0.52 \,K \,kg \,mol ^{1}$

The elevation in boiling point $\left(\Delta T_{b}\right)$ of 0.25 molal aqueous solution of a substance is

$\Delta T_{b}=K_{b} \times m=0.52 \times 0.25=0.13 K$