Question

The van't Hoff factor for 0.5 m aqueous CH₃COOH solution is 1.075. What is the experimentally observed \(\Delta T_f\) (in K) for this solution? \( K_f = 1.86 \, \text{K kg mol}^{-1} \)

• A. 1.156
• B. 1.075
• C. 1.0
• D. 0.95

Hint:

The van't Hoff factor accounts for the number of particles into which a solute dissociates in solution. Multiply by the freezing point depression constant to calculate \(\Delta T_f\).

Answer 1

The Correct Option is A

The freezing point depression (\(\Delta T_f\)) is given by the formula: \[ \Delta T_f = i . K_f . m \] Where: - \(i\) is the van't Hoff factor (1.075), - \(K_f\) is the freezing point depression constant (1.86 K kg mol\(^{-1}\)), - \(m\) is the molality (0.5 m).
Substituting these values, the calculated value of \(\Delta T_f\) is 1.156 K.