| Names | |
|---|---|
| Other names hexasodium diorthosilicate | |
| Identifiers | |
3D model (JSmol) | |
| EC Number |
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PubChem CID | |
| UNII | |
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| Properties | |
| Na6O7Si2 | |
| Molar mass | 306.102 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
Sodium pyrosilicate is the chemical compound Na
6Si
2O
7. It is one of the sodium silicates, specifically a pyrosilicate, formally a salt of the unstable pyrosilicic acid H
6Si
2O
7. [1] [2]
The anhydrous solid has the triclinic crystal structure, with space group P1 (a = 5.8007(8) Å, b = 11.5811(15) Å, c = 23.157(3) Å, α = 89.709(10)°, β = 88.915(11)°, γ = 89.004(11)°, V = 1555.1(4) Å3, Z = 8, Dx = 2.615 g·cm−3, μ(Mo‐Kα) = 7.94 cm−1). The Si
2O6−
7 anions are arranged in layers parallel to the (100) plane, with the sodium cations distributed in 24 distinct crystallographic positions, coordinated by 4 to 6 near oxygen atoms. Some of the 4-coordinated sodium atoms can be interpreted as parallel columns of edge-sharing NaO
4 tetrahedra. The columnar arrangement forms tunnels that house the remaining sodium cations. Twinning at a microscopic scale simulates a much larger monoclinic C centered lattice (V′ = 6220 Å3, Z = 32). [3]
