Question

Equivalent weight of $H_3{PO}_2$ in a reaction is found to be half of its molecular weight. It can be due to the :

• A. reaction of its two $H^{+}$ ions
• B. oxidation to $H_3{PO}_2$
• C. both (a) and (b)
• D. none of the above

Answer 1

Answer: (B)

oxidation to $H_3{PO}_2$

$H_{3}P{O}_2$ is a monobasic acid so it can not give two $H^{+}$ ions.
$H_{3}P{O}_2\to H_{3}P{O}_3$
Oxidation number changes by 2 so its equivalent weight is $\frac{M}{2}$.