Sodium oxide

Structure

The structure of sodium oxide has been determined by X-ray crystallography. Most alkali metal oxides (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 , with sodium ions tetrahedrally coordinated to 4 oxide ions and oxide cubically coordinated to 8 sodium ions.

Preparation

Sodium oxide is produced by the reaction of sodium with sodium hydroxide, sodium peroxide, or sodium nitrite: : To the extent that NaOH is contaminated with water, correspondingly greater amounts of sodium are employed. Excess sodium is distilled from the crude product.

A second method involves heating a mixture of sodium azide and sodium nitrate: :

Burning sodium in air produces a mixture of and sodium peroxide (): : :and :

A third much less known method involves a single displacement reaction when heating sodium metal with iron(III) oxide (rust):

:

the reaction should be done in an inert atmosphere to avoid the reaction of sodium with the air instead.

Applications

Glassmaking

Glasses are often described in terms of their sodium oxide content although they do not really contain . Furthermore, such glasses are not made from sodium oxide, but the equivalent of is added in the form of "soda" (sodium carbonate), which loses carbon dioxide at high temperatures: : : :

A typical 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. Such soda-lime glass has a much lower melting temperature than pure silica and has slightly higher elasticity. These changes arise because the -based material is somewhat more flexible.

Reactions

Sodium oxide reacts readily and irreversibly with water to give sodium hydroxide: : Because of this reaction, sodium oxide is sometimes referred to as the base anhydride of sodium hydroxide (more archaically, "anhydride of caustic soda").

References

References

1. Zumdahl, Steven S.. (2009). "Chemical Principles 6th Ed.". Houghton Mifflin Company.
2. {{Sigma-Aldrich
3. (1934). "Gitterstruktur der oxyde, sulfide, selenide und telluride des lithiums, natriums und kaliums". [[Zeitschrift für Elektrochemie und Angewandte Physikalische Chemie]].
4. Wells, A. F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press {{ISBN. 0-19-855370-6
5. {{Greenwood&Earnshaw2nd
6. E. Dönges. (1963). "Handbook of Preparative Inorganic Chemistry, 2nd Ed.". Academic Press.