Question

Calculate the equivalent weight of phosphoric acid [for reaction that replace all three(3) hydrogen ions]

Answer 1

$3NaOH + H_3PO_4 \to 3H_2O + Na_3PO_4$

The above is an example of a reaction where phosphoric acid loses all three protons.

Equivalent weight of an acid = $\dfrac{\textsf{Molecular weight of acid}}{\textsf{Basicity of acid}}$

molecular weight of phosphoric acid = 98

$\therefore$ Its Equivalent weight = $\dfrac{98}3$ = 32.67