Sodium peroxide

Sodium peroxide
Other names Sodium dioxide Flocool Solozone Disodium peroxide
Identifiers
CAS number	1313-60-6 Y
PubChem	14803
EC number	215-209-4
UN number	1504
RTECS number	WD3450000
Properties
Molecular formula	Na2O2
Molar mass	77.98 g/mol
Appearance	yellow to white powder
Density	2.805 g/cm3
Melting point	675 °C
Boiling point	decomp.
Solubility in water	reacts violently
Structure
Crystal structure	Hexagonal
Thermochemistry
Std enthalpy of formation ΔfHo298	−513 kJ/mol
Standard molar entropy So298	95 J K−1 mol−1
Hazards
MSDS	External MSDS
EU Index	011-003-00-1
EU classification	Oxidant (O) Corrosive (C)
R-phrases	R8, R35
S-phrases	(S1/2), S8, S27, S39, S45
NFPA 704	0 2 1 OX
Flash point	Non-flammable
Related compounds
Other cations	Lithium peroxide Potassium peroxide Rubidium peroxide Caesium peroxide
Related sodium oxides	Sodium oxide Sodium superoxide
Related compounds	Sodium hydroxide Hydrogen peroxide
Y peroxide (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Sodium peroxide is the inorganic compound with the formula Na₂O₂. This solid is the product when sodium is burned with oxygen.^[1] It is a strong base and a potent oxidizing agent. It exists in several hydrates and peroxyhydrates including Na₂O₂·2H₂O₂·4H₂O, Na₂O₂·2H₂O, Na₂O₂·2H₂O₂, and Na₂O₂·8H₂O.^[2]

Properties

Sodium peroxide crystallizes with hexagonal symmetry.^[3] Upon heating, the hexagonal form undergoes a transition into a phase of unknown symmetry at 512 °C.^[4] With further heating above the 675 °C melting point, the compound decomposes, releasing O₂, before reaching a boiling point.^[5]

Sodium peroxide is hydrolyzed to give sodium hydroxide and hydrogen peroxide according to the reaction:

Na₂O₂ + 2 H₂O → 2 NaOH +H₂O₂

Preparation

The synthesis is no longer of commercial significance since the development of efficient routes to hydrogen peroxide.^{[dubious – discuss][2]} Sodium peroxide formerly was prepared on a large scale by the reaction with sodium with oxygen at 130–200 °C, a process that generates sodium oxide, which in a separate stage absorbs oxygen:^[4]

4 Na + O₂ → 2 Na₂O

2 Na₂O + O₂ → 2 Na₂O₂

More specialized routes have been developed. At ambient temperatures (0–20 °C), O₂ reacts with a dilute (0.1–5.0 mole percent) sodium amalgam. 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 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

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^[4] and Flocool.^[5] 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.

References

1. ^ Greenwood, Norman N.; Earnshaw, A. (1984). Chemistry of the Elements. Oxford: Pergamon. p. 98. ISBN 0-08-022057-6. 
2. ^ ^{a b} Harald Jakob, Stefan Leininger, Thomas Lehmann, Sylvia Jacobi, Sven Gutewort “Peroxo Compounds, Inorganic” Ullmann's Encyclopedia of Industrial Chemistry, 2007, Wiley-VCH, Weinheim. doi:10.1002/14356007.a19_177.pub2
3. ^ Tallman, R. L.; Margrave, J. L.; Bailey, S. W. (1957). "The Crystal Structure Of Sodium Peroxide". J. Am. Chem. Soc. 79 (11): 2979–80. doi:10.1021/ja01568a087. 
4. ^ ^{a b c} Macintyre, J. E., ed. Dictionary of Inorganic Compounds, Chapman & Hall: 1992.
5. ^ ^{a b} Lewis, R. J. Sax's Dangerous Properties of Industrial Materials, 10th ed., John Wiley & Sons, Inc.: 2000.

External links

• International Chemical Safety Card 1606