Question #44543

A 3d transition metal $M$ is unique in its series for possessing a positive standard reduction potential ($E^\circ_{M^{2+}/M} > 0$). An aqueous solution is prepared by dissolving $0.1\text{ mol}$ of its chloride salt, \ce{MCl2}, in $1\text{ kg}$ of water. To this solution, $0.5\text{ mol}$ of \ce{KCN} is added, resulting in the evolution of a toxic gas that escapes completely, and the formation of a stable, tetrahedral mononuclear complex of $M$. Assuming 100% dissociation of all soluble salts and ideal behavior, what is the depression in freezing point ($\Delta T_f$) of the final solution? ($K_f$ of water = $1.86\text{ K kg mol}^{-1}$)