(i) Give a method for the manufacture of hydrogen peroxide and explain the reactions involved therein.
(ii) Illustrate oxidising, reducing and acidic properties of hydrogen peroxide with equations.
(i)It can be prepared by acidification of barium peroxide which is done by adding H2SO4. The excess water molecules then produced are evaporated under reduced pressure. The reaction for which is as follows-
BaO.8H2O (s) + H2SO4 (aq) → BaSO4(s) + H2O2 (aq) + 8H2O (l)
H2O2 acts as an oxidizing as well as reducing agent in both acidic and alkaline medium. This can be illustrated by following examples-
A. Oxidizing action in acidic medium-
2Fe2+ + 2H+ + H2O2 → 2Fe3+ + 2H2O
B. reducing agent in acidic medium-
2MnO4- + 6H+ + 5H2O2 → 2Mn2+ + 8H2O + 5O2
C. oxidizing agent in basic medium-
2Fe2+ + H2O2 → 2Fe3+ + 2OH-
D. reducing agent in basic medium-
I2 + H2O2 + OH-→ 2I- +2H2O + O2
(ii) Acidic property of Hydrogen peroxide-
It turns blue litmus red but its dilute solution is almost neutral to litmus which means it is a weak acid.
Its acidic nature can be further supported by its reaction with NaOH (base).
NaOH + H2O2 → NaHO2 + 2H2O
Since, H2O2 is a weak acid therefore CO2 is not produced as final product.
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