Sodium oxide

Sodium oxide
Names
	IUPAC name Sodium oxide
	Other names Disodium oxide
Identifiers
CAS Number	1313-59-3 ;
3D model (JSmol)	Interactive image;
ECHA InfoCard	100.013.827
EC Number	215-208-9;
PubChem CID	73971;
UNII	3075U8R23D ;
UN number	1825
CompTox Dashboard (EPA)	DTXSID0049781 ;
	InChI InChI=1S/2Na.O/q2*+1;-2;
	SMILES [O-2].[Na+].[Na+];
Properties
Chemical formula	Na2O
Molar mass	61.979 g·mol−1
Appearance	white solid
Density	2.27 g/cm3
Melting point	1,132 °C (2,070 °F; 1,405 K)
Boiling point	1,950 °C (3,540 °F; 2,220 K) sublimates
Sublimation; conditions	sublimates at 1275 °C
Solubility in water	reacts violently to form NaOH
Solubility	reacts with ethanol
Magnetic susceptibility (χ)	−19.8·10−6 cm3/mol
Structure
Crystal structure	Antifluorite (face centered cubic), cF12
Space group	Fm3m, No. 225
Coordination geometry	Tetrahedral (Na+); cubic (O2−)
Thermochemistry
Heat capacity (C)	72.95 J/(mol·K)
Std molar; entropy (So298)	73 J/(mol·K)
Std enthalpy of; formation (ΔfH⦵298)	−416 kJ/mol
Gibbs free energy (ΔfG˚)	−377.1 kJ/mol
Hazards
Main hazards	corrosive, reacts violently with water
Safety data sheet	ICSC 1653
GHS pictograms
GHS hazard statements	H314
GHS precautionary statements	P280
NFPA 704 (fire diamond)	0 3 1 W
Flash point	non-flammable
Related compounds
Other anions	Sodium sulfide; Sodium selenide; Sodium telluride
Other cations	Lithium oxide; Potassium oxide; Rubidium oxide; Caesium oxide
Related sodium oxides	Sodium peroxide; Sodium superoxide
Related compounds	Sodium hydroxide
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Sodium oxide is a chemical compound with the formula Na₂O. It is used in ceramics and glasses. The compound is the base anhydride of sodium hydroxide; when water is added to sodium oxide, NaOH is produced.

Na₂O + H₂O → 2 NaOH

The alkali metal oxides M₂O (M = Li, Na, K, Rb) crystallise in the antifluorite structure. In this motif the positions of the anions and cations are reversed relative to their positions in CaF₂, with sodium ions tetrahedrally coordinated to 4 oxide ions and oxide cubically coordinated to 8 sodium ions.^[3]^[4]

Preparation

Sodium oxide is produced by the reaction of sodium with sodium hydroxide, sodium peroxide, or sodium nitrite:^[5]

2 NaOH + 2 Na → 2 Na₂O + H₂

Na₂O₂ + 2 Na → 2 Na₂O

2 NaNO₂ + 6 Na → 4 Na₂O + N₂

Most of these reactions rely on the reduction of something by sodium, whether it is hydroxide, peroxide, or nitrite.

Burning sodium in air will produce Na₂O and about 20% sodium peroxide Na₂O₂.

6 Na + 2 O₂ → 2 Na₂O + Na₂O₂

A more accessible way of producing it in the laboratory consists in decomposing the sodium salt of ascorbic acid at temperatures over 209 Celsius degrees.

Applications

Glassmaking

Sodium oxide is a significant component of most glass, although it is added in the form of "soda" (sodium carbonate). Typically, manufactured glass contains around 15% sodium oxide, 70% silica (silicon dioxide) and 9% lime (calcium oxide). The sodium carbonate "soda" serves as a flux to lower the temperature at which the silica mixture melts. Soda glass has a much lower melting temperature than pure silica, and has slightly higher elasticity. These changes arise because the silicon dioxide and soda have reacted to form sodium silicates of the general formula Na₂[SiO₂]_x[SiO₃].

Na₂CO₃ → Na₂O + CO₂

Na₂O + SiO₂ → Na₂SiO₃

References

^ ^a ^b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A23. ISBN 0-618-94690-X.
^ ^a ^b ^c Sigma-Aldrich Co., Sodium oxide. Retrieved on 2014-05-25.
^ Zintl, E.; Harder, A.; Dauth B. (1934). "Gitterstruktur der oxyde, sulfide, selenide und telluride des lithiums, natriums und kaliums". Z. Elektrochem. Angew. Phys. Chem. 40: 588–93. doi:10.1002/bbpc.19340400811.
^ Wells, A. F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.
^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.

External links

Sodium oxide information at Webelements.

[b1-1] Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A23. ISBN 0-618-94690-X.

[sigma-2] Sigma-Aldrich Co., Sodium oxide. Retrieved on 2014-05-25.

[3] Zintl, E.; Harder, A.; Dauth B. (1934). "Gitterstruktur der oxyde, sulfide, selenide und telluride des lithiums, natriums und kaliums". Z. Elektrochem. Angew. Phys. Chem. 40: 588–93. doi:10.1002/bbpc.19340400811.

[4] Wells, A. F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.

[5] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.

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