| Sodium oxide | |
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Sodium oxide |
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Other names
Disodium oxide |
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| Identifiers | |
| CAS number | 1313-59-3 |
| PubChem | 73971 |
| UN number | 1825 |
| Properties | |
| Molecular 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 enthalpy of formation ΔfH |
−414.2 kJ/mol |
| Standard molar entropy S |
75.1 J mol−1 K−1 |
| Hazards | |
| MSDS | ICSC 1653 |
| EU Index | Not listed |
| 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 |
| Related sodium oxides | Sodium peroxide Sodium superoxide |
| Related compounds | Sodium hydroxide |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Sodium oxide (SOX) is a chemical compound with the formula Na2O. It is used in ceramics and glasses, though not in a raw form. Treatment with water affords sodium hydroxide.
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]
Contents |
Sodium oxide is produced by the reaction of sodium with sodium hydroxide, sodium peroxide, or sodium nitrite:[3]
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.
Sodium oxide is a significant component of glasses and windows although it is added in the form of "soda" (sodium carbonate). Sodium oxide does not explicitly exist in glasses, since glasses are complex cross-linked polymers. 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 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 react to form sodium silicates of the general formula Na2[SiO2]x[SiO3].