Silicate of sodium, meta

Sodium metasilicate is a fine crystalline powder of white or gray color, readily soluble in water, forming crystalline hydrates, absorbs carbon dioxide and water in air. It is an inorganic compound, a salt of an alkali metal sodium and metasilicic acid.

Aqueous solutions have a strongly alkaline reaction and are chemically identical to those of alkalis. Concentrated solutions form a colloidal liquid glass solution. Under the action of acids on aqueous solutions of sodium metasilicate, it decomposes with the release of a silicic acid gel. It decomposes in hot water.

Sodium metasilicate exists in two crystalline forms (crystalline hydrates): with five water molecules (melting point 78.2 ° C) and with nine water molecules (melting point 48 ° C).