Occurrence
Sodium sulfate occurs in nature as the minerals mirabilite and thenardite. While thenardite is the anhydrous form of Na2SO4, mirabilite is a naturallyoccurring decahydrate, Na2SO4•10H2O.
Sodium sulfate is one of the most important sodium salts. The decahydrate,commonly known as the Glauber’s salt, was first prepared by Johann Glauber in the seventeenth century as a by-product in making hydrochloric acid from sulfuric acid and sodium chloride.
Physical Properties
Anhydrous sodium sulfate is a white crystalline powder; orthorhombic or hexagonal structure; hygroscopic; refractive index 1.468; hardness 2.8 Mohs; density 2.664 g/cm3; melts at 884°C; soluble in water, insoluble in ethanol.
The decahydrate consists of colorless monoclinic crystals; refractive index 1.394; hardness 1.8 Mohs; density 1.4 6g/cm3; decomposes at 32°C; soluble in water; insoluble in ethanol.
Production
Sodium sulfate is mined from its natural mineral deposits and subjected to purification. Sodium sulfate is synthesized by the Mannheim process or Hargreaves process. Manheim’s process is based on Glauber’s reaction between sulfuric acid and sodium chloride:
2NaCl + H2SO4 → Na2SO4 + 2HCl↑
The process was devised by Johann Glauber to produce hydrochloric acid. Sodium sulfate is isolated from the solution by fractional crystallization. Hargreaves’ process also was developed to produce hydrochloric acid. It is a variation of Mannheim’s method. In this method, sulfur dioxide is used instead of sulfuric acid. The reaction is as follows:
4NaCl + 2SO2 + O2 + 2H2O → 2Na2SO4 + 4HCl↑
Sodium sulfate also is obtained as a byproduct of manufacturing phenol by caustic fusion.
Chemical Properties
White or almost white, crystalline powder or colourless, transparent crystals.
Uses
Sodium sulfate decahydrate may be used to deepen the color while dyeing cotton fabrics.6
Uses
Sodium sulfate decahydrate is used as a laboratory reagent to precipitate protein. It is largely used as filler in powdered home laundry detergents. It facilitates in leveling, reducing negative charges on fibers, thereby allows dye to penetrate evenly. It avoids the corrosion of stainless steel vessels used in dyeing. It is also used as a laxative and effectively replaces the drug paracetamol in the body.
Uses
Sodium sulfate decahydrate is used in manufacturing paper pulp by the Kraft Process. Other uses are in manufacturing glass and ultramarine; in dyeing and printing textiles; as a filler in synthetic detergents; and for standardizing dyes. A major use of anhydrous sodium sulfate is as an agent to remove water from organic solvents and their extracts for organic synthesis and instrumental analysis. Sodium sulfate decahydrate is a common laboratory reagent. Also, it is used to prepare other sodium salts.
Definition
ChEBI: Sodium sulfate decahydrate is a hydrate. It has a role as a cathartic. It contains a sodium sulfate.
General Description
Sodium sulfate decahydrate (Glauber′s salt, mirabilite, Na
2SO
4·10H
2O) is the decahydrate salt of sodium sulfate. Its crystal structure has been investigated by single-crystal neutron diffraction studies. Its crystallization enthalpy has been evaluated. It can be synthesized by reacting MnSO
4, thiophene-2,5-dicarboxylic acid and sodium glutamate.
Purification Methods
Crystallise sodium sulfate from water at 30o (1.1mL/g) by cooling to 0o. It becomes anhydrous at 32o.
