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sodium peroxide[′sōd·ē·əm pə′räk‚sīd]
Na2O2, a peroxide-type compound of sodium that contains the O22– anion. Pure sodium peroxide is a colorless powder, while the technical-grade product is a yellowish powder; the yellow tinge is due to an impurity, the superoxide NaO2. The melting point is about 600°C. Sodium peroxide decomposes with the release of O2 upon heating above 300°C.
When dissolved in water, sodium peroxide is hydrolyzed according to the reaction Na2O2 + 2H2O = 2NaOH + H2O2. The reaction is accompanied by the release of heat and by partial decomposition of H2O2 to give H2O and O2. Sodium peroxide reacts with moist atmospheric carbon dioxide to release oxygen according to the equation 2Na2O2 + 2CO2 = 2Na2CO3 + O2; this reaction is used to regenerate air in enclosed spaces. Sawdust, cotton, oil, and paper ignite upon contact with sodium peroxide.
Sodium peroxide is obtained by the oxidation of sodium at about 300°C in dry air that is free of CO2. It is used as a solid substitute for hydrogen peroxide in the bleaching of various materials and as a strong oxidizing agent in laboratory work.