Chemistry - Liquid Solution Question with Solution | TestHub

Depression in freezing point,

${\mathrm{\Delta T}}_{\mathrm{f}}={\mathrm{k}}_{\mathrm{f}}\times \mathrm{m}$

Where,

$\mathrm{m}=\mathrm{Molality}=\frac{\mathrm{Weight}\mathrm{ }\mathrm{of}\mathrm{ }\mathrm{solute}\times 1000}{\mathrm{Molecualr}\mathrm{ }\mathrm{weight}\mathrm{ }\mathrm{of}\mathrm{ }\mathrm{solute}\mathrm{ }\times \mathrm{Weight}\mathrm{ }\mathrm{of}\mathrm{ }\mathrm{solvent}}$

$=\frac{1.5\times 1000}{60\times 250}$

${\mathrm{\Delta T}}_{\mathrm{f}}$$=0{.1}^{\mathrm{o}}\mathrm{C}\mathrm{ }{\mathrm{molal}}^{-1}$

$\Rightarrow {\mathrm{\Delta T}}_{\mathrm{f}}={\mathrm{k}}_{\mathrm{f}}\times 0.1$

$0.01={\mathrm{k}}_{\mathrm{f}}\times 0.1$

$\therefore {\mathrm{k}}_{\mathrm{f}}=\frac{0.01}{0.1}$

$=0.1$