sodium hydroxide

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sodium hydroxide,

chemical compound, NaOH, a white crystalline substance that readily absorbs carbon dioxide and moisture from the air. It is very soluble in water, alcohol, and glycerin. It is a causticcaustic,
any strongly corrosive chemical substance, especially one that attacks organic matter. A caustic alkali is a metal hydroxide, especially that of an alkali metal; caustic soda is sodium hydroxide, and caustic potash is potassium hydroxide.
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 and a strong base (see acids and basesacids and bases,
two related classes of chemicals; the members of each class have a number of common properties when dissolved in a solvent, usually water. Properties
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). Commonly known as caustic soda, lye, or sodium hydrate, it is available commercially in various solid forms, e.g., pellets, sticks, or chips, and in water solutions of various concentrations; both solid and liquid forms vary in purity. The major use of sodium hydroxide is as a chemical and in the manufacture of other chemicals; because it is inexpensive, it is widely used wherever a strong base is needed. It is also used in producing rayon and other textiles, in making paper, in etching aluminum, in making soaps and detergents, and in a wide variety of other uses. The principal method for its manufacture is electrolytic dissociation of sodium chloride; chlorine gas is a coproduct. Small amounts of sodium hydroxide are produced by the soda-lime process in which a concentrated solution of sodium carbonate (soda) is reacted with calcium hydroxide (slaked lime); calcium carbonate precipitates, leaving a sodium hydroxide solution.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Sodium Hydroxide


(caustic soda, soda lye), NaOH, a caustic alkali; colorless crystals. Density, 2.13 g/cm3; melting point, 320°C. The industrial product is an opaque, white solid mass with a radial fracture. Sodium hydroxide is hygroscopic; a large amount of heat is liberated upon its reaction with water. Aqueous solutions of NaOH exhibit a strong alkaline reaction. The solubility of sodium hydroxide in water is 52.2 percent at 20°C and 75.8 percent at 80°C. It forms crystal hydrates, such as NaOH-H2O, which is stable at ordinary temperatures (12.3°-61.8°C). Upon exposure to air, NaOH absorbs CO2 and is converted into sodium carbonate. Sodium hydroxide has a destructive effect on skin, paper, and other materials; even very small quantities of NaOH cause extremely severe damage upon contact with the eyes.

Sodium hydroxide is prepared by electrolysis of NaCl solutions or by boiling a Na2 CO3solution with milk of lime: Na2C03+ Ca (OH)2 CaC03+ 2NaOH. The sodium hydroxide solution is evaporated, and the residue is heated to the melting point and then poured into molds. Electrolysis yields chlorine in addition to NaOH. Sodium hydroxide is one of the main products of the modern chemical industry; it is widely used both in the chemical industry and in many other sectors.

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

sodium hydroxide

[′sōd·ē·əm hī′dräk‚sīd]
(inorganic chemistry)
NaOH White, deliquescent crystals; absorbs carbon dioxide and water from air; soluble in water, alcohol, and glycerol; melts at 318°C; used as an analytical reagent and chemical intermediate, in rubber reclaiming and petroleum refining, and in detergents. Also known as sodium hydrate.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

sodium hydroxide

a white deliquescent strongly alkaline solid used in the manufacture of rayon, paper, aluminium, soap, and sodium compounds. Formula: NaOH
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
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Our results are partially in agreement with (Verma and Jaiswal, 1981) who studied the effect of NaOH treated wheat straw in Sahiwal steers and reported that crude fiber digestibility had significantly increased.
The proposed study concluded that a better way to do the glycolysis of rigid PU is using GCL as the solvent and NaOH as the catalyst, which has achieved rates of 100% PU conversion in a product.
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where [M.sub.RS] is the mass of the fine aggregate (kg), [M.sub.LS] is the mass of the coarse aggregate (kg), [S.sub.G(RS)] is the specific gravity of the fine aggregate, [S.sub.G(LS)] is the specific gravity of the coarse aggregate, [V.sub.FA] is the volume of high-calcium fly ash, [V.sub.NaOH] is the volume of NaOH, [mathematical expression not reproducible] is the volume of [Na.sub.2]Si[O.sub.3], and [V.sub.air] is the volume of entrapped air.
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