Question

Account for the following in the preparation of `H_(2)O_(2)` from barium perioxide `(BaO_(2))` and dilute `H_(2)SO_(4)`.
(a) A thin paste of hydrated barium perioxde is used instead of nahydrous perioxide.
(b) The temperature of the reaction mixture is kept at `0^(@)C`.
(c ) The final solution must be kept slightly acidic.

Answer 1

(a) Anhydrous `BaO_(2)` is not used becasuse the reaction with dilute `H_(2)SO_(4)` is highly exothermic and will accelerate the decomposition of `H_(2)O_(2)` into `H_(2)O and O_(2)`. Moreever, in this case a layer of `BaSO_(4)` initially formed in the reaction gets deposited over barium and any futher raction with acid does not take place. Keeping this in mind. hydrated barium peroxide `(BaO_(2).8H_(2)O)` is used
(b) The temperature of the reaction mixture is kept at `0^(@)C` becasue higher temperature will cause the decomposition of the hydrogen peroxide.
(c ) The traces of `H^(+)` ions present in the final solution will act as inhibitor and will retard the decomposition of `H_(2)O_(2)`.