Sodium oxide is a chemical compound with the formula . It is used in ceramics and glasses. It is a white solid. However, the compound itself is rarely encountered and instead, the name "sodium oxide" is used to describe components of various materials such as glasses and fertilizers which contain oxides that include sodium and other elements.
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 calcium fluoride|, 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: