Question

How is hydrogen peroxide prepared by electrolytic method?

Answer 1

Preparation of Hydrogen Peroxide:

Let us have a look at the various methods of preparation for hydrogen peroxide:

When barium peroxide is acidified and the excess water is removed by the process of evaporation under reduced pressure, we obtain hydrogen peroxide. The following reaction will clarify this:

Pρ+gz+v22=k

Pρ+gz+v22=k

BaO2.8H2O(s)+H2SO4(aq)→BaSO4(s)+H2O2(aq)+8H2O(l)

When acidified sulphate solution is electrolyzed at high current density, peroxodisulphate is obtained. Peroxodisulphate is then hydrolyzed to get hydrogen peroxide.

2HSO−4(aq) Electrolysis−→−−−−−−− HO3SOOSO3H(aq) Hydrolysis−→−−−−−−− 2HSO−4(aq)+2H+(aq)+H2O2(aq)

Properties of Hydrogen Peroxide:

Physical properties:

In pure state hydrogen peroxide is almost colorless (very pale blue) liquid.It melts at 272.4 K and has a boiling point of 423 K (extrapolated).It is miscible in water in all proportions and forms hydrates.

Chemical properties:

Hydrogen peroxide in both acidic and basic medium acts as an oxidizing as well as the reducing agent. The following reactions will give a clear picture:

Oxidizing nature in an acidic medium
PbS(s)+4H2O2(aq)→PbSO4(s)+4H2O(l)The reducing nature in an acidic medium
HOCl+H2O2→H3O++Cl−+O2Oxidizing nature in a basic medium
Mn2++H2O2→Mn4++2OH−Reducing nature in a basic medium
I2+H2O2+OH−→2I−+2H2O+O2

Storage of Hydrogen Peroxide:

Hydrogen peroxide decomposes when exposed to sunlight, this process is catalyzed by traces of alkali metals. Therefore, hydrogen peroxide is stored in wax-lined glass or plastic containers and kept in dark. It should also be kept away from dust particles because dust can induce explosive decomposition of this compound.