Question

Calculate the cryoscopic constant of a solvent if depression in freezing point of \(0\cdot 3\) m solution of nonelectrolyte is \(0\cdot 48\) K

• A. \(1\cdot 1\text{ K kg mol}^{-1}\)
• B. \(1\cdot 6\text{ K kg mol}^{-1}\)
• C. \(2\cdot 2\text{ K kg mol}^{-1}\)
• D. \(2\cdot 6\text{ K kg mol}^{-1}\)

Hint:

Use the depression equal to Kf times molality.

Answer 1

The Correct Option is B

Step 1: Proportionality:
$K_f$ is the depression produced by a 1 molal solution.

Step 2: Scale:
A 0.3 m solution gives 0.48 K, so 1 m would give $\frac{0.48}{0.3} = 1.6$ K. Hence $K_f = 1.6$ (B).

Final Answer:
$K_f = 1.6$ K kg/mol. \[ \boxed{1.6\text{ K kg mol}^{-1}} \]