Question

Equivalent weight of $H_{3}P{O}_2$ when it disproportionates into $P{H}_3$ and $H_{3}P{O}_3$ (mol. wt. = $M$) is :

• A. $M$
• B. $\frac{M}{2}$
• C. $\frac{M}{4}$
• D. $\frac{3M}{4}$

Answer 1

The correct option is D $\frac{3M}{4}$

The disproportionation reaction is $3H_{3}P{O}_2\to P{H}_3+2H_{3}P{O}_3$.

n-factor $=\frac{\text{No. of electrons involved}}{\text{No. of molecules involved}}=\frac{4}{3}$

Eq. wt. $=\frac{mol.wt.}{n-factor}=\frac{M\times 3}{4}$

The equivalent weight of phosphorus is $\frac{3M}{4}$.