Sodium peroxide is an inorganic compound with the formula Na2O2. It is the product of sodium ignited in excess oxygen. The pure substance is a white solid, but commercial and laboratory samples often appear as a yellowish solid due to sodium superoxide impurities. It is a strong base. This metal peroxide exists in several hydrates and peroxyhydrates including Na2O2·2H2O2·4H2O, Na2O2·2H2O, Na2O2·2H2O2, and Na2O2·8H2O. The octahydrate, which is simple to prepare, is white, like the pure anhydrous material.
Properties Sodium peroxide crystallizes with hexagonal symmetry. Upon heating, the hexagonal form undergoes a transition into a phase of unknown symmetry at 512 °C. With further heating above the 657 °C boiling point, the compound decomposes to Na2O, releasing O2.
2 Na2O2 → 2 Na2O + O2
Preparation Commercially, sodium peroxide is produced from the elements in a two-stage process. First sodium is oxidized to sodium oxide:
4Na + O2 → 2 Na2O Subsequently, this oxide is treated with more oxygen:
2 Na2O + O2 → 2 Na2O2 This was the method by which the substance was discovered in 1810 by Joseph Louis Gay-Lussac and Louis Jacques Thénard, as well as how it was for the first time commercially made by Hamilton Castner in the 1890s. It may also be produced by passing ozone gas over solid sodium iodide inside a platinum or palladium tube. The ozone oxidizes the sodium to form sodium peroxide. The iodine can be sublimed by mild heating. The platinum or palladium catalyzes the reaction and is not attacked by the sodium peroxide. The octahydrate can be produced by treating sodium hydroxide with hydrogen peroxide.
Uses Sodium peroxide hydrolyzes to give sodium hydroxide and hydrogen peroxide according to the reaction
Na2O2 + 2 H2O → 2 NaOH + H2O2 Sodium peroxide was used to bleach wood pulp for the production of paper and textiles. Presently it is mainly used for specialized laboratory operations, e.g., the extraction of minerals from various ores. Sodium peroxide may go by the commercial names of Solozone and Flocool. In chemistry preparations, sodium peroxide is used as an oxidizing agent. It is also used as an oxygen source by reacting it with carbon dioxide to produce oxygen and sodium carbonate:
Na2O2 + CO2 → Na2CO3 + 1⁄2 O2 Na2O2 + H2O + 2 CO2 → 2 NaHCO3 + 1⁄2 O2 It is thus particularly useful in scuba gear, submarines, etc. Lithium peroxide and potassium superoxide have similar uses. Sodium peroxide was once used on a large scale for the production of sodium perborate, but alternative routes to that cleaning agent have been developed.
References
External links International Chemical Safety Card 1606
