Question

The freezing point of 0.05 molal solution of a non-electrolyte in water is

• A. 1.86 °C
• B. -0.93 °C
• C. -0.093 °C
• D. 0.93°C

Answer 1

Answer: (C)

-0.093 °C

Answer 2

For a non-electrolyte, the freezing point depression is given by:

$$\Delta T_f = K_f \times m$$

where $K_f$ (water) = 1.86 °C/m and $m = 0.05$ molal.

Thus,

$$\Delta T_f = 1.86 \times 0.05 = 0.093\,°\text{C}$$

Since the freezing point of pure water is 0 °C, the freezing point of the solution is:

$$0 - 0.093 = -0.093\,°\text{C}$$