11th Chemistry NCERT notes

H2O2 was discovered by J.L. Thenard in 1818. It is an important compound used in pollution control treatment of domestic and industrial effluents.

Preparation of Hydrogen Peroxide:

From Barium peroxide

Preparation of Hydrogen Peroxide from barium peroxide

By electrolysis of 50% H2SO4

Electrolysis of a cold 50% solution of H2SO4 at high current density in an electrolytic cell using pe as anode and graphite as cathode.

Preparation of Hydrogen Peroxide by electrolysis of dilute H2SO4

At Cathode:

Preparation of Hydrogen Peroxide by electrolysis of dilute H2SO4

At Anode:

Preparation of Hydrogen Peroxide by electrolysis of dilute H2SO4

peroxodisulphuric acid formed around anode is withdrawn and then distilled with water under reduced pressure.

Preparation of Hydrogen Peroxide by electrolysis of dilute H2SO4

Physical Properties of Hydrogen Peroxide

Physical Properties of Hydrogen Peroxide

Structure of Hydrogen Peroxide

Hydrogen peroxide has a non-planar structure. The molecular dimensions in the gas phase and solid phase are shown in fig.

Structure of Hydrogen Peroxide

Storage of Hydrogen Peroxide (H2O2)

It is stored in the presence of traces of alcohol, acetanilide or sodium pyrophosphate which slow down the rate of decomposition of hydrogen peroxide.

Chemical Properties of H2O2

Acidic nature of H2O2:

It is weakly acidic in nature and pure hydrogen peroxide turns blue litmus red.

H2O2 as Oxidising agent:

It acts as a strong oxidising agent in acidic as well as in basic medium.

Oxidising agent

H2O2 as Reducing agent:

  • In acidic medium

H2O2 as Reducing agent

  • In basic medium

H2O2 as Reducing agent

Bleaching properties:

Its bleaching action is due to oxidation by atomic oxygen and permanent.

Bleaching properties

dye + [O] dye is oxidized and bleached

Uses of H2O2:

  • It is used as a mild disinfectant. It is marketed as perhydrol (an Antiseptic).
  • It is used in the manufacture of high quality detergents.
  • It is used in the synthesis of hydroquinone tartaric acid and certain food products and pharmaceuticals.
  • It is used as bleaching agent for textiles, paper pulp etc.
  • It is used for pollution control treatment of domestic and industrial effluents.
  • 93% H202 is used as an oxidant for rocket fuel.

 

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