The melting point of anhydrous sodium sulfate is 884 °C. This chemical is a white, hygroscopic, orthorhombic crystal or powder with a density of 2.664 g/cm3. It can be dissolved in water and glycerol but is insoluble in ethanol. This compound is unreactive to most oxidising or reducing agents at normal temperatures. It is a common laboratory reagent for kjeldahl nitrogen determination. Sodium sulfate is also used as a drying agent for organic solutions.
Sodium sulfate is commonly produced as a byproduct of other chemical processes such as the production of hydrochloric acid from sodium chloride and sulfuric acid in the Mannheim process or sulfur dioxide from coal gasification using the Hargreaves process. It is a valuable chemical for its industrial and commercial applications, such as manufacturing glass, paper pulp and textile fabrics; as a dyeing aid and a laxative.
It is also used in the production of nitric acid and metallurgical chemicals such as ferric sulfate. The anhydrous form of this compound is the most commonly used. It is available as a dry powder, pellets and wet solid. Its structure is orthorhombic bipyramidal and it has a salty taste with no odor.
Sodium sulfate is generally considered non-toxic, although it should be handled with care as it can be irritating to the eyes and respiratory tract. It is also a corrosive irritant and should be kept away from any moist materials, such as textiles. Its main use in the laboratory is as an inert drying agent to remove traces of moisture from organic solutions.