Question

Equivalent weight of $H_{3}PO_{2}$ when it disproportionates into $PH_{3}$ and $H_{3}PO_{3}$ is (mol. wt. of $H_{3}PO_{2} = M$)

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

Answer 1

Answer: (B)

$H_{2}PO_{2} \to PH_{3}$
$P^{+}+4e^{-} \to P^{3-}$
$\therefore Eq. wt. \left(H_{3}PO_{2}\right)=M/4$ $H_{3}PO_{2} \to\text{H}_{3}PO_{3} $
$P^{+} \rightarrow P^{3+}+2e^{-} $
$\therefore Eq, w.t.\left(H_{3}PO_{2}=M 2\right) Hence, $
$Eq. wt. \left(H_{3}PO_{2}\right)=\frac{M}{4}+\frac{M}{2}=\frac{3}{4}M$