Question
Phosphoric acid is preferred over sulphuric acid in preparing hydrogen peroxide from peroxides. Why?
✓
Answer
In the preparation of $\mathrm{H}_2 \mathrm{O}_2$ from barium peroxide and sulphuric acid, the use of sulphuric acid has a disadvantage as it catalyses the decomposition of $\mathrm{H}_2 \mathrm{O}_2$ formed. In place of $\mathrm{H}_2 \mathrm{O}_2$, weak acids like ortho phosphoric acid, carbonic acid are preferred. All heavy metal impurities present in $\mathrm{BaO}_2$ are removed as insoluble phosphates and decomposition of $\mathrm{H}_2 \mathrm{O}_2$ is prevented.
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