Question

Molal depression constant for a solvent is $4.0\, kg\, mol^{-1}$. The depression in the freezing point of the solvent for $0.03\, mol\, kg^{-1}$ solution of ${K2SO4}$ is : (Assume complete dissociation of the electrolyte)

• A. 0.12 K
• B. 0.36 K
• C. 0.18 K
• D. 0.24 K

Answer 1

Answer: (B)

0.36 K

Answer 2

$K_f$ = $4\, K-kg/mol$ $m = 0.03\, mol/kg$ $i = 3$ $\Delta T_f = iK_f \times m$ $\Delta T_f = 3 \times 4 \times 0.03 = 0.3 6K$