Sodium metasilicate sodium metasilicate (water) name Chinese alias of sodium metasilicate pentahydrate sodium metasilicate pentahydrate; sodium metasilicate pentahydrate CAS RN 10213-79-3 Formula Na2SiO3 · 5H2O Molecular weight 212.13 Properties Appearance white square crystallization or spherical particles. Melting point of 72.2 ℃ The relative density of 0.7 to 1.0 Solubility soluble in water and dilute alkali, insoluble in alcohol and acid. Alkaline aqueous solution. Uses for the super-concentrated detergent washing powder, detergents, metal cleaners, food industry, also used in paper bleaching, cotton yarn cooking, porcelain clay dispersion