Sodium pyrosilicate

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]

Sodium pyrosilicate
Names
Other names
hexasodium diorthosilicate
Identifiers
3D model (JSmol)
EC Number
  • 239-671-1
UNII
  • InChI=1S/6Na.O7Si2/c;;;;;;1-8(2,3)7-9(4,5)6/q6*+1;-6
    Key: PMYUVOOOQDGQNW-UHFFFAOYSA-N
  • [Si](O[Si]([O-])([O-])[O-])([O-])([O-])[O-].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+]
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).
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Infobox references

Structure

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]

See also

References
  1. Myron C Waddell (1932): "Process of purifying technical sodium pyrosilicate hydrates". US patent US1931364A.
  2. J. F. Schairer and N. L. Bowen (1956): "The system Na
    2    O    —Al
    2    O
    3    —SiO
    2    ". American Journal of Science, volume 254, issue 3, pages 129-195 doi:10.2475/ajs.254.3.129
  3. Volker Kahlenberg, Thomas Langreiter, and Erik Arroyabe (2010): "Na6Si2O7 – The Missing Structural Link among Alkali Pyrosilicates". Zeitschrift für anorganishe und allgemeine Chemie (Journal for Inorganic and General Chemistry), volume 636, issue 11, pages 1974-1979. doi:10.1002/zaac.201000120
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