Sodium sulfate is a white, crystalline solid that occurs naturally as a mineral called thenardite. It is also used in the chemical industry as an inert drying agent for organic liquids. Aqueous solutions of the salt are pH neutral. The melting point of anhydrous sodium sulfate is 884 deg C.
Sodium sulfate can be produced from sodium chloride and sulfuric acid in a process called the Leblanc process. The sodium sulfate is then isolated from the solution by fractional crystallization. Another method of purification is via the decahydrate form.
Sodium sulfate is soluble in water and glycerol. However, it is insoluble in ethanol. In the presence of a solution of the compound, it forms hexagonal crystals. At higher temperatures, it will convert to sodium sulfide.
Sodium sulfate has a high affinity for various organic compounds and iron. It is used in detergents and soaps. Other uses include dyeing textiles and carpet fresheners. Some of the products containing this substance include powdered home laundry detergents.
When heated, sodium sulfate emits toxic fumes. It is important to keep it away from surface waters. For this reason, the bulk of the sodium sulfate is purified through the decahydrate phase.
Sodium sulfate, anhydrous is used as a leveling agent in dyeing textiles. Its chemical stability allows it to be used with many other substances. The concentration range of anhydrous sodium sulfate can be determined using aliquots of extract atomized into a flame photometer.
Sodium sulfate, decahydrate, has a heat of fusion of 82 kJ/mol. Its crystalline form, decahydrate, has a ph of 7. Anhydrous sodium sulfate has a thickness of 2.664 g/cm3 and is relatively hard.