Sodium oxide

Sodium oxide
Names
	IUPAC name Sodium oxide
	Other names Disodium oxide
Identifiers
CAS Number	1313-59-3 ;
ECHA InfoCard	100.013.827
PubChem CID	73971;
UN number	1825
CompTox Dashboard (EPA)	DTXSID0049781 ;
Properties
Chemical formula	Na2O
Molar mass	61.9789 g/mol
Appearance	White solid
Density	2.27 g/cm3
Melting point	1132°C
Boiling point	1950 °C decomposes
Solubility in water	reacts violently to form NaOH
Structure
Crystal structure	Antifluorite (face centered cubic), cF12
Space group	Fm3m, No. 225
Coordination geometry	Tetrahedral (Na+); cubic (O2–)
Thermochemistry
Std molar; entropy (S⦵298)	75.1 J mol−1 K−1
Std enthalpy of; formation (ΔfH⦵298)	−414.2 kJ/mol
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Corrosive, reacts violently with water
Flash point	Non-flammable
Related compounds
Other anions	Sodium sulfide; Sodium selenide; Sodium telluride
Other cations	Lithium oxide; Potassium oxide; Rubidium oxide; Caesium oxide
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Sodium oxide (SOX) is a chemical compound with the formula Na₂O. It is used in ceramics and glasses. Treatment with water affords sodium hydroxide.

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.^[1]^[2]

Applications

Glass making

Sodium oxide is a significant component of glasses although it is not added in the form of Na₂O nor do discrete sodium oxide components exist in glasses, which are complex crosslinked polymers. Typically, glass contains around 15% sodium oxide, the other components being silica (silicon dioxide) and lime (calcium oxide) at around 70% and 9%, respectively. The soda serves as a flux to lower the temperature at which the silica melts. Soda glass has a lower melting temperature vs pure silica, and has improved mechanical properties due to its slight increases in elasticity. These changes arise because the silicon dioxide and soda react to form sodium silicates of the general formula Na₂[SiO₂]_x[SiO₃].

Preparation

Sodium oxide is produced by the reaction of sodium with sodium hydroxide, sodium peroxide, or sodium nitrite:^[3]

2 NaOH + 2 Na → 2 Na₂O + H₂

Na₂O₂ + 2 Na → 2 Na₂O

2 NaNO₂ + 6 Na → 4 Na₂O + N₂

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

6 Na + 2 O₂ → 2 Na₂O + Na₂O₂

References

^ 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{{citation}}: CS1 maint: multiple names: authors list (link)
^ Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.
^ Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.

External links

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[1] 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{{citation}}: CS1 maint: multiple names: authors list (link)

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

[3] Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.

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