Sodium sulfate is chemically very stable, being unreactive toward most oxidising or reducing agents at normal temperatures. At high temperatures, it can be reduced to sodium sulfide. It is a neutral salt, which forms aqueous solutions with pH of 7. The neutrality of such solutions reflects the fact that Na2SO4 is derived, formally speaking, from the strong acid sulfuric acid and a strong base sodium hydroxide. Sodium sulfate reacts with an equivalent amount of sulfuric acid to give an equilibrium concentration of the acid salt sodium bisulfate.

Detergent, Pulp and Paper, Textile, Glass Industry, and other applications.

Sodium sulfate is the sodium salt of sulfuric acid. When anhydrous, it is a white crystalline solid of formula Na2SO4 known as the mineral thenardite. The decahydrate, Na2SO4·10H2O, is known as Glauber’s salt. Sodium sulfate is mainly used for the manufacture of detergents and in the Kraft process of paper pulping, though it has many other uses. About half of the world’s production is from the natural mineral form of the decahydrate (mirabilite), and half from by-products of chemical processes.