The observed and normal molar masses of compound $M X_{2}$ are 65.6 and 164 respectively. The percen

Question

The observed and normal molar masses of compound $M X_{2}$ are 65.6 and 164 respectively. The percent degree of ionisation of $M X_{2}$ is $\_\_\_\_$ %. (Nearest integer)\

Professor PC Thomas Classes · Answer

(75) : van't Hoff factor,\ $i=\frac{	ext { Normal molar mass }}{	ext { Observed molar mass }}=\frac{164}{65.4}=2.5$\ $n$ for $M X_{2}\left(M^{2+}+2 X^{-}ight)=3$\ Thus, $\alpha=\frac{i-1}{n-1}=\frac{2.5-1}{3-1}=0.75$\ % degree of ionisation = $75 \%$\