$i =1+(2-1) \alpha$

$i =1+\alpha$

$\Delta T _{ f }= ik _{ f } m$

$0.5=(1+\alpha)(1.86)\left(\frac{\left(\frac{9.45}{94.5}\right)}{\left(\frac{500}{1000}\right)}\right)$

$\frac{5}{3.72}=1+\alpha \quad \Rightarrow \alpha=\frac{1.28}{3.72}$

$\alpha=\frac{32}{93}$

$\begin{array}{*{20}{c}} {ClC{H_2}COOH \rightleftharpoons ClC{H_2}CO{O^ \ominus } + {H^ + }} \\ {\,\,\,\,\,\,\,\,\,C - C\alpha \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C\alpha \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C\alpha \,\,\,\,\,\,\,\,\,\,\,\,\,} \end{array}$

$=0.036$

$K _{ a }=36 \times 10^{-3}$