Question

A solution containing 6.8 g of non-ionic solute in 100 g of water was found to freeze at -0.93 $^\circ$C.$K_f$ for water is 1.86, If the mol. mass of solute is

• A. 13.6
• B. 34
• C. 68
• D. 136

Answer 1

Answer: (D)

136

Answer 2

$\Delta T_{f}=k_{f} m$ $m=$ mola city $0.93=1.86 \times \frac{6.8}{M \times 0.1}$ $M=$ molar mass of solute $M=\frac{6.8 \times 1.86}{0.43 \times 0.1}$ $m=136 \,gm / mole$