Question

Equivalent mass of $H_{3}P{O}_2$ (Molar mass $=66$) when it disproportionates into $P{H}_3$ and $H_{3}P{O}_3$ is :

• A. 66
• B. 33
• C. 16.5
• D. 49.5

Answer 1

The correct option is D 49.5

Reaction:

$H_{3}P{O}_2\to P{H}_3+H_{3}P{O}_3$

+1 -3 +3

So, the equivalent mass (if it goes to $P{H}_3$) of $H_{3}P{O}_2=\frac{M}{4}=\frac{66}{4}=16.5$

the equivalent mass (if it goes to $H_{3}P{O}_3$) of $H_{3}P{O}_2=\frac{M}{2}=\frac{66}{2}=33$

So, total equivalent mass $=16.5+33=49.5$