`H_(2)SO_(4)` acts as a catalyst for decomposition of `H_(2)O_(2)` . Therefore , some weaker acids such as `H_(3)PO_(4)` is preferred over `H_(2)SO_(4)` for preparing `H_(2)SO_(4)` for preparing `H_(2)O_(2)` from peroxides.
`" " 3BaO_(2) + 2H_(3)PO_(4) to Ba_(3) (PO_(4))_(2) + 3H_(2)O_(2)`
Further, this method has the advantage over `BaO_(2)-H_(2)SO_(4)` method since almost all the heavy metal (e.g., Pb etc.) impurities present in `BaO_(2)` and which catalyse the decomposition of `H_(2)O_(2)` are removed as insoluble phosphates. As a result , the resulting solution of `H_(2)O_(2)` has good keeping properties.
