Formula Na2O2 Melting point 675 °C Appearance yellow to white powder | Molar mass 77.98 g/mol Density 2.8 g/cm³ | |
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Sodium peroxide
Sodium peroxide is the inorganic compound with the formula Na2O2. This yellowish solid is the product of sodium ignited in excess oxygen. It is a strong base. It exists in several hydrates and peroxyhydrates including Na2O2·2H2O2·4H2O, Na2O2·2H2O, Na2O2·2H2O2, and Na2O2·8H2O.
Contents
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 675 °C melting point, the compound decomposes to Na2O, releasing O2, before reaching a boiling point.
2 Na2O2 → 2 Na2O + O2Preparation
Sodium peroxide can be prepared on a large scale by the reaction of metallic sodium with oxygen at 130–200 °C, a process that generates sodium oxide, which in a separate stage absorbs oxygen:
4 Na + O2 → 2 Na2O 2 Na2O + O2 → 2 Na2O2It 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 is freed into iodine crystals, which can be sublimed by mild heating. The platinum or palladium catalyzes the reaction and is not attacked by the sodium peroxide.
Uses
On contact with water sodium peroxide is hydrolyzed to give sodium hydroxide and hydrogen peroxide according to the reaction:
Na2O2 + 2 H2O → 2 NaOH + H2O2Sodium 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; it is thus particularly useful in scuba gear, submarines, etc. Lithium peroxide has similar uses.
2Na2O2 + 2CO2 → 2Na2CO3 + O2