calcium hydroxide

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calcium hydroxide,

Ca(OH)2, colorless crystal or white powder. It is prepared by reacting calcium oxidecalcium oxide,
chemical compound, CaO, a colorless, cubic crystalline or white amorphous substance. It is also called lime, quicklime, or caustic lime, but commercial lime often contains impurities, e.g., silica, iron, alumina, and magnesia.
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 (lime) with water, a process called slaking, and is also known as hydrated lime or slaked lime. When heated above 580°C; it dehydrates, forming the oxide. Like the oxide, it has many uses, e.g., in limingliming
, application to the soil of calcium in various forms, generally as ground limestone, but also as marl, chalk, shells, or hydrated lime. Lime benefits soil by neutralizing acidity, improving texture, and increasing the activity of soil microorganisms.
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 soil, in sugar refining, and in preparing other compounds. It is a strong base and is widely used as an inexpensive alkali, often as a suspension in water (milk of lime); it is used in leather tanning to remove hair from hides. It is used in whitewashwhitewash,
white fluid commonly used as an inexpensive, impermanent coating for walls, fences, stables, and other exterior structures. It varies in composition, being generally a mixture of lime (quicklime), water, flour, salt, glue, and whiting, with other ingredients such as
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, mortarmortar,
in building, mixture of lime or cement with sand and water, used as a bedding and adhesive between adjacent pieces of stone, brick, or other material in masonry construction.
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, and plaster. It is only slightly soluble in water, about 0.2 grams per 100 cubic centimeters, so its solutions are weakly basic. Limewater is a clear, saturated water solution of calcium hydroxide. It is used in medicine to treat acid burns and as an antacid. Because calcium hydroxide readily reacts with carbon dioxide, CO2, to form calcium carbonate, a mixture of gases can be tested for the presence of CO2 by shaking it with limewater in a clear container; if CO2 is present, a cloudy calcium carbonate precipitate will form.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Calcium Hydroxide


slaked lime, Ca(OH)2, a strong base; colorless crystals. Density, 2.24 g per cm3.

Commercial calcium hydroxide is a fluffy white powder. It dehydrates to CaO when heated. Calcium hydroxide is only slightly soluble in water: 0.165 g per 100 g H2O at 20°C and 0.077 g at 100°C. Its solubility increases sharply in the presence of salts. An aqueous solution of calcium hydroxide is known as lime water; a suspension is known as milk of lime. Calcium hydroxide readily absorbs atmospheric carbon dioxide: Ca(OH)2 + CO2 = CaCO3 + H2O. The compound serves as an inexpensive alkali. It is also used in construction.

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

calcium hydroxide

[′kal·sē·əm hī′dräk‚sīd]
(inorganic chemistry)
Ca(OH)2 White crystals, slightly soluble in water; used in cement, mortar, and manufacture of calcium salts. Also known as hydrated lime.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

hydrated lime

1. Same as dry hydrate.
2. Quick lime mixed with water, on the job, to form a lime putty; slaked lime.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

calcium hydroxide

a white crystalline slightly soluble alkali with many uses, esp in cement, water softening, and the neutralization of acid soils. Formula: Ca(OH)2
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005