H2O2

Hydrogen peroxide, with the chemical formula H2O2, is a simple inorganic compound that exists as a colorless liquid in dilute solutions. It is a strong oxidizer used for disinfection, bleaching, and chemical synthesis. In water, hydrogen peroxide behaves as a weak acid with a pKa around 11.7, existing as H2O2 or HO2− depending on pH. It decomposes exothermically into water and oxygen, a process that can be catalyzed by heat, light, metal ions, or enzymes such as catalase.

Industrial production of hydrogen peroxide is dominated by the anthraquinone process, in which an organic solution undergoes cyclic oxidation and reduction to generate H2O2, which is then extracted and concentrated. Concentration varies widely: household products typically contain about 3% hydrogen peroxide, consumer antiseptic and cleaning formulations may be around 6–10%, and laboratory or food-grade solutions are commonly around 30%, with industrial and specialty applications using higher concentrations (often 50% or more) for decontamination or as an oxidizer in rocket propellants.

Common applications include disinfection and sterilization of surfaces and wounds (in dilute form), bleaching of paper, textiles, and hair products, and as a reactive oxygen source in chemical synthesis. It is also employed in environmental remediation to oxidize pollutants.

Safety and handling require care: concentrated solutions are corrosive to skin and eyes and can cause burns; decomposition releases oxygen and can build pressure in closed containers, posing explosion risks if mixed with organic materials or catalysts. Storage in dark, well-ventilated conditions and stabilization additives are used to slow decomposition. Hydrogen peroxide was first prepared and studied in the early 19th century by Louis Jacques Thénard.