Chemical Reactions and uses of Hydrogen Peroxide
Hydrogen peroxide is a strong oxidizing agent owing to its decomposition to oxygen and water.
2 H2O2 (l) 2H2O(l) + O2 (g)
The oxidation state of oxygen is -1 in hydrogen peroxide while it is zero in oxygen molecule.
Hydrogen peroxide oxidizes iron(II) to iron(III), iodide to iodine, lead sulphide to lead sulphate, potassium ferrocyanide to potassium ferricyanide and manganese(II) to manganese(IV)
2Fe2+ + 2H+ + H2O2 2Fe3+ + 2H2O
2I- + 2H+ + H2O2 I2 + 2H2O
PbS + 4H2O2 PbSO4 + 4H2O
2[Fe(CN)6]4- + 2H+ + H2O2 2[Fe(CN)6]3- + 2H2O
Mn2+ + H2O2 Mn4+ + 2OH-
Hydrogen peroxide also acts as a reducing agent when it is reduced to O2 in which the oxidation state of oxygen is zero. Thus, it reduces permanganate to manganese (II), iron (III) to iron (II), ferricyanide to ferrocyanide, periodate to iodate, ozone to oxygen and silver oxide to metallic silver.
+ 6H+ + 5H2O2 2Mn2+ + 8H2O + 5O2
2Fe3+ + 2OH- + H2O22Fe2+ + 2H2O + O2
2[Fe(CN)6]3- + 2OH + H2O2 2[Fe(CN)6]4- + 2H2O + O2
KIO4 + H2O2 KIO3 + H2O + O2
O3 + H2O2 2O2 + H2O
Ag2O+ H2O22Ag + H2O + O2
Uses of Hydrogen Peroxide
Hydrogen peroxide is used as a bleaching agent for hair, wool feathers, grains, etc. Its dilute solution is used as an antiseptic and has medicinal value. Liquid hydrogen peroxide is used as a fuel for rockets and submarines. It forms coloured complexes with titanium, vanadium and chromium salts and is used for their detection. Hydrogen peroxide is employed as an oxidizing agent and in the preparation of peroxides. Organic peroxides are very important compounds in initiating polymerization reactions and as antiseptics.