Na2SO4

Sodium sulfate, with the formula Na2SO4, is an inorganic salt composed of two sodium ions and a sulfate dianion. Under normal conditions it commonly exists as the decahydrate Na2SO4·10H2O, known as Glauber’s salt, but the anhydrous form Na2SO4 (thenardite) is also stable and widely used. The decahydrate is highly soluble in water and forms crystals at ambient temperatures; upon heating above about 32 °C, it loses water to yield the anhydrous salt.

Occurrence and forms in nature: Sodium sulfate occurs in natural evaporite deposits. The decahydrate form is called mirabilite, while the anhydrous form is thenardite. Mirabilite can crystallize from cold saline waters and gradually dehydrates to thenardite with increasing temperature or aridity.

Production and processing: Industrial production of Na2SO4 typically arises from neutralization reactions between sulfuric acid and sodium compounds, such as Na2CO3 (Na2CO3 + H2SO4 → Na2SO4 + CO2 + H2O) or the reaction of sulfuric acid with sodium chloride (2 NaCl + H2SO4 → Na2SO4 + 2 HCl). It can also be recovered from natural brines and evaporitic mineral deposits.

Uses: Sodium sulfate serves as a versatile filler and processing aid in the papermaking, detergent, textiles, and glass industries. It acts as a drying agent for solvents, a buffering and stabilizing component in some formulations, and a source of sulfate in chemical syntheses. Historically, Glauber’s salt (the decahydrate) has been used as a laxative.

Safety: Na2SO4 is of relatively low toxicity but can irritate the eyes and skin in dusty forms. Standard safety practices apply for handling and dust control.