SODIUM META SILIKATE

SODIUM META SILIKATE

SODIUM META SILIKATE


Sodium metasilicate is the chemical substance with formula Na2SiO3, which is the main component of commercial sodium silicate solutions. It is an ionic compound consisting of sodium cations Na+and the polymeric metasilicate anions [–SiO2−3–]n. It is a colorless crystalline hygroscopic and deliquescent solid, soluble in water (giving an alkaline solution), but not in alcohols.


Contents
1    Preparation and properties
2    Structure
3    See also
4    References
Preparation and properties
The anhydrous compound can be prepared by fusing silicon dioxide SiO
2 (silica, quartz) with sodium oxide Na
2O in 1:1 molar ratio.[2]

The compound crystallizes from solution as various hydrates, such as

pentahydrate Na
2SiO
3·5H
2O (CAS 10213-79-3, EC 229-912-9, PubChem, 57652358)
nonahydrate Na
2SiO
3·9H
2O (CAS 13517-24-3, EC 229-912-9, PubChem 57654617)[3]
Structure
In the anhydrous solid, the metasilicate anion is actually polymeric, consisting of corner-shared {SiO4} tetrahedra, and not a discrete SiO32− ion.[4]

In addition to the anhydrous form, there are hydrates with the formula Na2SiO3·nH2O (where n = 5, 6, 8, 9), which contain the discrete, approximately tetrahedral anion SiO2(OH)22− with water of hydration. For example, the commercially available sodium silicate pentahydrate Na2SiO3·5H2O is formulated as Na2SiO2(OH)2·4H2O, and the nonahydrate Na2SiO3·9H2O is formulated as Na2SiO2(OH)2·8H2O.[5] The pentahydrate and nonahydrate forms have their own CAS Numbers, 10213-79-3 and 13517-24-3 respectively.

See also
Potassium metasilicate
Sodium orthosilicate
Sodium pyrosilicate