- Hydrogen peroxide was first discovered by Thenard in 1818.
- Hydrogen peroxide is a clear liquid.
- Hydrogen peroxide is slightly more viscous than water.
- It is a strong oxidizer.
- In dilute solution it appears colorless.
- It is used as a bleach or cleaning agent.
- Traces of hydrogen peroxide are found in atmosphere and in certain plants.
Hydrogen peroxide is prepared by Merck's process. In this method calculated quantities of sodium peroxide to ice cold dilute 20% solution of sulphuric acid. 30% of hydrogen peroxide is obtained by this process.
Na2O2 + H2SO4 → Na2SO4 + H2O2
Pure hydrogen peroxide is obtained by reacting BaO2 with an acid.
BaO2 + H2SO4 → BaSO4 + H2O2
3BaO2 + 2H3PO4 → Ba3(PO)4 + 3H2O2
Phosphoric acid is preferred to H2SO4 because soluble impurities like Barium persulphate tends to decompose H2O2 while H3PO4 is act as preservative ( negative catalyst ) for hydrogen peroxide.
Hydrogen peroxide is manufactured by the electrolysis of 50% sulphuric acid followed by vacuum distillation. Here 30% of pure hydrogen peroxide is obtained.