Question

$75.2g{C}_6{H}_{5}OH$ (phenol) is dissolved in $1$ kg of solvent of $K_f=14Kmolalit{y}^{-1}$. If depression in freezing point is $7K$, then the % dimerisation of phenol is_________.

Answer 1

$\underset{\underset{1-\alpha }{1}}{2C_6{H}_{5}OH}\rightleftharpoons \underset{\underset{\frac{1}{2}}{0}}{(C_6{H}_{5}OH{)}_2}$

$\because \Delta T_f=\frac{1000K_f\times w}{m\times W}(1-\alpha \frac{\alpha }{2})$

$7=\frac{1000\times 14\times 75.2}{94\times 1000}(1-\frac{\alpha }{2})$

$\therefore \alpha =0.75$ or 75%