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Write preparation of Hydrogen peroxide. |
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Answer» Solution :(i) Acidifying barium peroxide and removing excess water by EVAPORATION under reduced PRESSURE gives hydrogen peroxide. `BaO_2. 8H_2O_((s)) + H_2SO_(4(aq)) to BaSO_(4(s)) + H_2O_(2(aq)) + 8H_2O_((l))` (ii) Peroxodisulphate, obtained by electrolytic oxidation of acidified sulphate SOLUTIONS at high current density, on hydrolysis yields hydrogen peroxide. `2HSO_(4(aq))^(-) overset"Electrolysis"to HO_3SOOSO_3H_((aq)) overset"Hydrolysis"to 2HSO_(4(aq))^(-) + 2H_((aq))^(+) + H_2O_(2(aq))` This METHOD is now used for the laboratory preparation of `D_2O_2` . `K_2S_2O_(8(s)) + 2D_2O_((l)) to 2KDSO_(4(aq)) + D_2O_(2(l))` (iii)Industrially it is prepared by the auto-oxidation of 2-alklylanthraquinols. (2-ethyl anthraquinol) `O_2"(air)"to H_2O_2`+ (Oxidised product.) In this case 1% `H_2O_2` is formed. It is extracted with water and concentrated to ~30% (by mass) by distillation under reduced pressure. It can be further concentrated to ~85% by careful distillation under low pressure. The remaining water can be frozen out to obtain pure `H_2O_2`. |
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