Sodium pyrosilicate is the

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

. It is one of the

sodium silicate Sodium silicate is a generic name for chemical compounds with the formula or ·, such as sodium metasilicate , sodium orthosilicate , and sodium pyrosilicate . The anions are often polymeric. These compounds are generally colorless transparent ...

s, specifically a

pyrosilicate A pyrosilicate is a type of chemical compound; either an ionic compound that contains the pyrosilicate anion , or an organic compound with the hexavalent ≡-O-≡ group. The anion is also called disilicateViktor Renman (2017): "Structural and E ...

, formally a

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...

of the unstable

pyrosilicic acid Pyrosilicic acid is the chemical compound with formula or . It is one of the silicic acids and has pyrosilicate as its conjugate base. It was synthesized, using nonaqueous solutions, in 2017. :H6Si2O7(aq) -> 2 SiO2(s) + 3 H2O Pyrosilicic acid m ...

.Myron C Waddell (1932): "Process of purifying technical sodium pyrosilicate hydrates". US patent US1931364A.J. F. Schairer and N. L. Bowen (1956): "The system ——". ''American Journal of Science'', volume 254, issue 3, pages 129-195

Structure

The anhydrous solid has the

triclinic 180px, Triclinic (a ≠ b ≠ c and α ≠ β ≠ γ ) In crystallography, the triclinic (or anorthic) crystal system is one of the 7 crystal systems. A crystal system is described by three basis vectors. In the triclinic system, the crystal is ...

crystal structure, with space group P (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 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 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).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.

References

{{reflist Sodium compounds

Structure

See also

References