Question

Equivalent weight of :
(a) $H_{3}P{O}_2=\frac{molecularweight}{1}$
(b)$H_{3}P{O}_3=\frac{molecularweight}{2}$
(c)$H_{3}P{O}_4=\frac{molecularweight}{3}$
If true enter 1, else enter 0.

Answer 1

Equivalent weight of an acid is based on number of ionisable protons which is called Basicity. Ionisable hydrogen in attached to electronegative atom as $O$ and $X(F,Cl,Br,I)$
(a) $H_{3}P{O}_2$ has one ionisable hydrogen (monobasic acid)
$H_{3}P{O}_2\rightleftharpoons H_{2}P{O}_2^{-}+H^{+}$
Hence, equivalent weight=molecular weight
(b)$\underset{\left(dibasic\right)}{H_{3}P{O}_3}\rightleftharpoons HP{O}_3^{2-}+2H^{+}$
Hence, equivalent weight$=\frac{molecularweight}{2}$
(c)$\underset{\left(tribasic\right)}{H_{3}P{O}_4}\rightleftharpoons P{O}_4^{3-}+3H^{-}$
Hence, equivalent weight$=\frac{molecularweight}{3}$
Ionised hydrogen (circled) are attached to oxygen atoms.