H2O2, this compounds molecular weight is 34.02g/mol; it is a colorless, rather unstable oxidant with a bitter taste and caustic to the skin. Hydrogen peroxide will decompose, liberating oxygen. Pure hydrogen peroxide is stable, but the slightest impurity will enhance decomposition, often violently. Concentrated solutions of hydrogen peroxide are highly corrosive and toxic. H2O2 is used as bleach, deodorizer, and in the manufacturing of rocket fuel. The hydrogen peroxide in your bathroom is approximately 3 percent in water. In the atmosphere this is probably one of the oxidizers for sulfur dioxide in cloud water droplets that produces sulfuric acid, a major component in acid rain.
[Science; v 262; p 1883-1886; 1993] [Science; v 260; p 71-73; 1993.]
Source: Atmospheric Chemistry Glossary