Question

Phosphoric acid is preferred over sulphuric acid in preparing hydrogen peroxide from peroxides. Why?

Answer 1

$H_{2}S{O}_4$ can act as a catalyst and can activate the decomposition of $H_2{O}_2.$

Thus, weaker acids such as $H_{3}P{O}_4$ are preferred over $H_{2}S{O}_4,$ in preparation of $H_2{O}_2$ from peroxides.

For example – In preparation of $H_2{O}_2$ from barium peroxide $\left(Ba{O}_2\right),$ instead of $H_{2}S{O}_4,$ we use phosphoric acid such that all heavy metal impurities are removed as insoluble phosphates and decomposition of $H_2{O}_2$ can be prevented.