Na2SiO35H2O

Sodium silicate pentahydrate, with the chemical formula Na2SiO3·5H2O, is a crystalline salt of sodium and silicic acid. It is a hydrated form of sodium metasilicate, meaning it incorporates water molecules into its crystal structure. This compound typically appears as a white, crystalline solid.

Na2SiO3·5H2O is soluble in water, forming alkaline solutions. These solutions are often referred to as water glass. The pentahydrate form is one of several hydrates of sodium silicate, with other common forms including the anhydrous (Na2SiO3) and nonahydrate (Na2SiO3·9H2O) versions. The degree of hydration can influence the physical properties and solubility of the sodium silicate.

Industrially, sodium silicates are produced by fusing silica sand with sodium carbonate at high temperatures. The resulting molten product is then dissolved in water. Sodium silicate pentahydrate can be obtained through controlled crystallization from aqueous solutions.

This compound finds applications in various industries. It is used as a detergent builder, contributing to the cleaning power of laundry detergents and dishwashing soaps by softening water and dispersing dirt. It also serves as an adhesive, particularly in the manufacturing of corrugated cardboard and paper products. In construction, it can be used as a binder and a hardening agent for concrete. Other uses include its role as a corrosion inhibitor, a fluxing agent, and a component in the production of zeolites and silica gel.