Question

Freezing point of solution containing 50 cm3 of ethylene glycol in 50 g of water is -34 deg C. Calculate density of ethylene glycol. Kf= 1.86

Answer 1

Dear Student,

$$\begin{gathered} \mathrm{Ethylene}\mathrm{glycol}=50{\mathrm{cm}}^3 \\ {\mathrm{K}}_{\mathrm{f}}=1.86\mathrm{K}{\mathrm{kgmol}}^{-1} \\ \mathrm{Mass}\mathrm{of}\mathrm{ethylene}\mathrm{glycol}\left(\mathrm{w}\right)=\mathrm{V}\times \mathrm{d}=50\times \mathrm{d}\mathrm{g} \\ \mathrm{Mass}\mathrm{of}\mathrm{water}\left(\mathrm{W}\right)=50\mathrm{g} \\ ∆{\mathrm{T}}_{\mathrm{f}}=34°\mathrm{C} \\ ∆{\mathrm{T}}_{\mathrm{f}}={\mathrm{k}}_{\mathrm{f}}\mathrm{m} \\ \mathrm{m}=\frac{\mathrm{w}}{\mathrm{M}}\times \frac{1000}{\mathrm{W}}=\frac{50\times \mathrm{d}}{62}\times \frac{1000}{50} \\ \mathrm{or},34=1.86\times \frac{50\times \mathrm{d}}{62}\times \frac{1000}{50} \\ \mathrm{or},\mathrm{d}=1.133\mathrm{g}/{\mathrm{cm}}^3 \end{gathered}$$