Sodium Metasilicate

Sodium Metasilicate 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. The anhydrous compound can be prepared by fusing silicon dioxide SiO2 (silica, quartz) with sodium oxide Na2O in 1:1 molar ratio. In addition to the anhydrous form, there are hydrates with the formula Na2SiO3·nH2O (where n = 5, 6, 8, 9)


Molar Weight122.06 g/mol
Melting Point48°C (nonahydrate), 72°C (pentahydrate)
Density2.61 g/cm³
FormsCrystals, White

Uses and Applications

Key applications

  • Suspension agent
  • Buffer agent
  • Preservative
  • Binding agent
  • Stabilizing agent
  • Emulsifying agent


  • Pharma
  • Cleaning
  • Coatings & Construction
  • Water Treatment
  • Chemical Processing

Synonyms: Disodium metasilicate, disodium oxosilanebis(olate)

Chemical Formula: Na2O3Si

CAS Number: 6834-92-0, 13517-24-3 (Nonahydrate), 10213-79-3 (Pentahydrate)