Na2SiO2nO

Sodium metasilicate, commonly represented by the formula Na₂SiO₃ (often incorrectly written as Na₂SiO₂nO), is an inorganic compound composed of sodium, silicon, and oxygen. It exists primarily in two forms: a crystalline (anhydrous) and a hydrated (pentahydrate) variety. The anhydrous form is a white, amorphous powder, while the pentahydrate is a colorless, crystalline solid that dissolves readily in water.

Sodium metasilicate is produced industrially through the reaction of sodium carbonate (soda ash) with silica (sand) at high temperatures, typically around 1,000–1,200°C. The chemical reaction can be summarized as follows: Na₂CO₃ + SiO₂ → Na₂SiO₃ + CO₂. It is widely used in various applications due to its alkaline properties and ability to form silicates in solution.

One of the most common uses of sodium metasilicate is as a cleaning agent, particularly in detergents and household cleaners. It acts as a builder, enhancing the effectiveness of surfactants by softening water and preventing the redeposition of dirt. It is also employed in water treatment processes to control scale and corrosion in industrial and municipal systems. Additionally, sodium metasilicate serves as a pH adjuster in food and beverages, though its use is regulated due to potential health concerns at high doses.

In the construction industry, it is used as a waterproofing agent and in the production of cement and concrete additives. The compound also finds applications in the textile industry for dyeing and printing fabrics. Due to its mild alkaline nature, it is sometimes used in laboratory settings for pH neutralization and as a mild abrasive in some cleaning formulations.

While generally considered safe in moderate amounts, sodium metasilicate can irritate the skin, eyes, and respiratory tract, particularly in powder form. Proper handling and ventilation are recommended when working with the substance. Its chemical stability and versatility make it a valuable compound across multiple industries.