Question

Calculate the equivalent weight of the following substance as acid or base.

$PO{\left(OH\right)}_3$
If $M$ is the molecular weight and $E$ the equivalent weight, then :

• A. $E=\frac{M}{3}$
• B. $E=\frac{M}{4}$
• C. $E=\frac{M}{5}$
• D. None of these

Answer 1

The correct option is A $E=\frac{M}{3}$

1 mole of $PO{\left(OH\right)}_3$ contains 3 moles of replaceable hydrogen ions.

Hence, its equivalent weight is equal to one third of its molecular weight.

$\text{Equivalent mass of an acid}=\frac{\text{Molar mass of the acid}}{\text{Number of replaceable H atoms}}$

$E=\frac{\text{M}}{3}$

Hence the correct option is A.