sodium sulfate

sodium sulfate

sodium sulfate, chemical compound, Na₂SO₄. It is a white, orthorhombic crystalline compound at ordinary temperatures; above 100℃ it assumes a monoclinic structure, and above about 250℃ it assumes a hexagonal structure. Sodium sulfate is soluble in cold water and very soluble in hot water. It forms two hydrates; the decahydrate is Glauber's salt. Anhydrous sodium sulfate is found in nature as the mineral thenardite. The major commercial source of sodium sulfate is salt cake, a byproduct of the production of hydrochloric acid from sodium chloride (common salt) by treatment with sulfuric acid. It is obtained (with other chemicals) by evaporation of natural brines. It is also obtained as a byproduct of viscose rayon manufacture and in several other, less important ways. The principal use of sodium sulfate is in processing wood pulp for making kraft paper. It is also used in glass manufacture, textile dyeing, and synthetic detergents.

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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Sodium Sulfate

 

Na₂SO₄, a salt; colorless crystals. Occurs naturally as the mineral thenardite. Density, 2.698 g/cm³; melting point, 884°C. Solubility in water, 16.3 percent at 20°C and 29.8 percent at 100°C. Anhydrous Na₂SO₄ is stable at temperatures above 32.384°C; lower temperatures induce the crystallization of Na₂So₄·10H₂O. In nature, this crystal hydrate forms the mineral mirabilite (Glauber’s salt). Double salts of sodium sulfate with other sulfates, such as astrakhanite, Na₂SO₄·MgSO₄ · 4H₂O, and glauberite, Na₂SO₄·CaSo₄ are also known.

Large quantities of sodium sulfate are found in brine and in the bottom deposits of chloride-sulfate salt lakes and the gulf of Kara-Bogaz-Gol (USSR). The reaction 2NaCL + MgSO₄⇆MgCl₂ + Na₂So₄ takes place there upon a reduction in temperature. Sodium sulfate crystallizes in the form of mirabilite. Another method for the preparation of Na₂SO₄ is the reaction of NaCl and H₂SO₄ in special “sulfate” furnaces at 500°-55O°C, which also yields hydrochloric acid.

Sodium sulfate is used in glass-making, the manufacture of sulfate cellulose, soap-making, tanning, nonferrous metallurgy, and textile manufacture, as well as in medicine and veterinary science (as a laxative). Sodium bisulfate, NaHSO₄, and sodium disulfate (pyrosulfate), Na₂S₂O7, are used in the same way as KHSO₄ and K₂S₂O₇.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

sodium sulfate

[′sōd·ē·əm ′səl‚fāt]

(inorganic chemistry)

Na₂SO₄ Crystalline compound, melts at 888°C, soluble in water; used to make paperboard, kraft paper, glass, and freezing mixtures.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.