Na2SO47H2O

Na2SO47H2O refers to sodium sulfate heptahydrate, a crystalline form of sodium sulfate. Sodium sulfate is an inorganic compound with the chemical formula Na2SO4. In its heptahydrate form, it incorporates seven molecules of water into its crystal structure. This compound is also known as Glauber's salt or mirabilite.

Glauber's salt typically appears as white, crystalline solids. It is highly soluble in water and exhibits a cooling sensation when dissolved, similar to other hydrates. The transition between the anhydrous form (Na2SO4) and its hydrated forms, including the heptahydrate, is temperature-dependent. Below 32.38 degrees Celsius, the heptahydrate is the stable form in contact with a saturated solution. Above this temperature, it transforms into the decahydrate (Na2SO4·10H2O) or the anhydrous form.

Historically, Glauber's salt has found various applications. It was historically used as a purgative in medicine, although its use has largely been superseded by more modern treatments. Industrially, sodium sulfate in its various hydrated and anhydrous forms is used in the manufacturing of detergents, glass, textiles, and paper. It is also employed in chemical processes and as a drying agent. The presence of the water molecules in the heptahydrate structure affects its physical properties, such as its density and melting point, compared to the anhydrous form.