Hydrogen peroxide is an oxide of oxygen containing a higher proportion of oxygen compared to normal oxides.

Hydrogen peroxide is prepared in the laboratory by the action of cold dilute Sulphuric acid on barium peroxide. $$ H_2SO_4 + BaO_2 \rightarrow BaSO_4 + H_2O_2 $$ Barium peroxide and dilute sulphuric acid is usually used because barium tetraoxosulphate (VI) produced is insoluble and can be filtered off easily.

Hydrogen peroxide is manufactured industrially by the oxidation of propan-2-ol in the presence of oxygen at low pressure. $$(CH_3)_2CHOH + O_2 \rightarrow (CH_3)_C=O + H_2O_2 $$

1. It dissolves in water to give a very weak acidic solution.
2. Pure hydrogen peroxide is a pale blue syrupy liquid
3. It boils and decomposes at 150°C and freezes at -0.9°C.

1. Decomposition: Hydrogen peroxide decomposws on exposure to air to yield water and oxygen gas. $$ H_2O_2 \rightarrow H_2O + O_2 $$ The reaction is exothermic and can be accelerated using by heating, addition of alkalis, introduction of manganese (IV) oxide or finely divided platinum as catalyst.
   Propan-1,2,3-triol and mineral acids retard the decomposition of hydrogen peroxide and usually added to minimize the decomposition of commercial hydrogen peroxide .


2. Reducing action: Hydrogen peroxide behaves as a reducing agent in the presence of a strong oxidizing agent. In the process, oxygen gas is formed. $$ H_2O_2 \stackrel{[O]}{\rightarrow}\ H_2O+ O_2 + 2e^- $$
   1. With chlorine: Hydrogen peroxide reduces chlorine to hydrochloric acid $$H_2O_2 + Cl_2 \rightarrow HCl + O_2 $$
   2. With potassium permanganate: Hydrogen peroxide reduces purple potassium permanganate to pink manganese (II) ion .
   3. With silver oxide: Hydrogen peroxide redices silver oxide to silver
   $$Ag_2O_2 + H_2O_2 \rightarrow 2Ag + H_2O + O_2 $$


3. Oxidizing action: Hydrogen peroxide is a strong oxidizing agent as it can readily donate electrons or accept electrons. In this process, hydrogen peroxide is reduced to water. $$ H_2O_2 + 2H^+ + 2e^- \rightarrow 2H_2O $$
   1. With potassium iodide: Hydrogen peroxide reacts with potassium iodide solution acidified with tetraoxosulphate (VI) acid to liberate iodine. Here, hydrogen iodide is oxidized to iodine.
   $$H_2O_2 + KI \stackrel{[H_2SO_4]}{\rightarrow}\ 2H_2O + I_2 $$
   2. With lead (II) sulphide: Hydrogen peroxide reduces lead (II) sulphide to lead (II) tetraoxosulphate (VI) while itself been reduced to water
   $$PbS + H_2SO_4 \rightarrow PbSO_4 + 4H_2O $$

1. It is useful for the purification of water.
2. Hydrogen peroxide is used as an antiseptic
3. Liquid Hydrogen peroxide provides oxygen for the burning of fuel in space rockets
4. Due to its oxidizing action, hydrogen peroxide serves as a good bleaching agent on materials like silk, wool, feathers and human hair which would be easily damaged by sulphur (IV) oxide or chlorine.
5. Hydrogen peroxide is used in the treatment of white lead (II) paints blackened on exposure to atmospheric hydrogen sulphide. Lead (II) sulphide is oxidized to lead tetraoxosulphate (VI), thus restoring the white color. $$ PbS + 4H_2O_2 \rightarrow PbSO_4 + 4H_2O $$
6. Hydrogen peroxide is used in the manufacture of sodium dioxochlorate (III) and some organic peroxides which are used to start polymerization reactions