Sodium oxide 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.
In the typical application, glass
contains around 15% sodium oxide, the other components being silicon dioxide
and 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
Na2O forms when sodium is treated with oxygen.
- 4 Na + O2 → 2 Na2O
Burning sodium in air will produce Na2O and about 20% sodium peroxide Na2O2.
- 6 Na + 2 O2 → 2 Na2O + Na2O2
Pure Na2O can be prepared by reaction of liquid sodium with NaNO3.
- 10 Na + 2 NaNO3 → 6 Na2O + N2