Question

The freezing point depression of a 0.10 m solution of HF(aq) solution is $-{0.201}^{\circ }C$. Calculate the percent dissociation of HF(aq).

• A. 6
• B. 9
• C. 10
• D. 8

Answer 1

The correct option is D 8

The freezing point depression equation is:
$\Delta T=i{K}_{f}m$
The only value we do not know is i:
${0.201}^{\circ }C=\left(x\right)\left({1.86}^{\circ }C{m}^{-1}\right)\left(0.10m\right)x=1.08$
So $HF$ is about $8\%$ dissociated.