Question

Molal depression constant for water is $1.86^{o}C$. The freezing point of a 0.05 molal solution of a non-electrolyte in water is.

• A. $- 1.86^{o}C$
• B. $- 0.93^{o}C$
• C. $- 0.093^{o}C$
• D. $0.93^{o}C$

Answer 1

Answer: (C)

$- 0.093^{o}C$

Answer 2

$\Delta T_{f} = K_{f} \times \text{molality} = \text{1.86} \times \text{0.05} = \text{0.093}$°C

Thus freezing point = 0 – 0.093 = $- 0.093^{o}C$.