Question

Which one of the following $0.10M$ aqueous solutions will exhibit the largest freezing point depression ?

• A. $KHS{O}_4$
• B. glycine
• C. glucose
• D. hydrazine

Answer 1

The correct option is A $KHS{O}_4$

Freezing point depression of a solution is given by,
$△T_f=K_f\times m$
where,
$△T_f$ is the depression in freezing point.
$K_f$ is molal depression constant.
m is molality of solution.
i is Van't hoff factor
Since, all are of $0.1M$ aqueous solution,
$\Delta T_f\propto i$

Greater the value of $i$, greater will be the $\Delta T_f$ value.
Compound which does not show any dissociation with water will have van't hoff factor value of 1.
$\begin{array}{cc}Solute& i\\ \text{Glycine}& 1\\ KHS{O}_4& 2\\ \text{Hydrazine}& 1\\ \text{Glucose}& 1\end{array}$

Hence, freezing point depression will be highest for $KHS{O}_4$.