Sodium Metasilicate Pentahydrate

Sodium metasilicate is the chemical substance 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. This substance is produced by reacting molten sodium hydroxide (at a temperature above 320 °C) and silica:

SiO2 + 2NaOH - t → Na 2SiO3 + H2O