Sodium silicate is an inorganic sodium salt which has silicate as the counterion. It is also called Sodium metasilicate or Waterglass. The chemical formula of Sodium silicate is Na₂O·nSiO₂.

Sodium metasilicate is a flaked solid or powdered substance. It dissolves in water to produce alkaline solutions. It has a polymeric anion. In alkaline and neutral solutions it is stable whereas, in acidic solutions, the silicate ions will react with hydrogen ions and form silicic acids, which are likely to decompose into hydrated silicon on the dioxide gel. When further heated, it drives off the water and a hard translucent substance called silica gel is obtained.

Uses of Sodium silicate 

1. Sodium silicate is used in wastewater treatment plants as an iron flocculant and an alum coagulant.

2. It is used as hand-dyeing as a fixative.

3. It is used in Pottery.

4. It is widely used in food preservation, homebrewing, and aquaculture.