The freezing point depression of a solution containing $0.6 \mathrm{~g}$ of urea (molar mass $=60…
The freezing point depression of a solution containing $0.6 \mathrm{~g}$ of urea (molar mass $=60 \mathrm{~g} \mathrm{~mol}^{-1}$ ) in $100 \mathrm{~mL}$ of benzene (in $\mathrm{K}$ ) is $\left(K_f\right.$ of $\mathrm{CH}_3 \mathrm{COOH}=4.0 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$ )
0.30
0.58
0.40
0.24
Solution
Given,
Mass of urea $=0.6 \mathrm{~g}$
Molar mass of urea $=60 \mathrm{~g} \mathrm{~mol}^{-1}$
$K_f$ of benzene $=4.0 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$ and $100 \mathrm{~mL}$
benzene $=0.1 \mathrm{~L} \approx 0 . \mathrm{kg}$
$
\Delta T_f=K_f m
$
So, $\Delta T_f=4 \times \frac{0.6}{60} \times \frac{1}{0.1}=0.4$