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hydroxide(hīdrŏk`sīd), chemical compound that contains the hydroxyl (−OH) radicalradical,
in chemistry, group of atoms that are joined together in some particular spatial structure and that take part in most chemical reactions as a single unit. Important inorganic radicals include ammonium, NH4; carbonate, CO3 ; chlorate, ClO3
..... Click the link for more information. . The term refers especially to inorganic compounds. Organic compounds that have the hydroxyl radical as a functional groupfunctional group,
in organic chemistry, group of atoms within a molecule that is responsible for certain properties of the molecule and reactions in which it takes part. Organic compounds are frequently classified according to the functional group or groups they contain.
..... Click the link for more information. are called alcoholsalcohol,
any of a class of organic compounds with the general formula R-OH, where R represents an alkyl group made up of carbon and hydrogen in various proportions and -OH represents one or more hydroxyl groups.
..... Click the link for more information. ; the hydroxyl radical is also present in the carboxyl group of organic acids. Most metal hydroxides are bases—they form solutions that have an excess of OH− ions and a pH greater than 7, neutralize acids, and change the color of litmus from red to blue. Alkali metal hydroxides such as sodium hydroxidesodium 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 caustic and a strong base (see acids and bases).
..... Click the link for more information. are strong bases and are very soluble in water; alkaline–earth metal hydroxides such as calcium hydroxidecalcium hydroxide,
Ca(OH)2, colorless crystal or white powder. It is prepared by reacting calcium oxide (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.
..... Click the link for more information. (slaked lime) are much less soluble in water and are not as strongly basic. Magnesium hydroxide (milk of magnesiamilk of magnesia,
common name for the chemical compound magnesium hydroxide, Mg(OH)2. The viscous, white, mildly alkaline mixture that is used medicinally as an antacid and laxative is a suspension of approximately 8% magnesium hydroxide in water.
..... Click the link for more information. ) is only slightly basic. Some hydroxides (e.g., aluminum hydroxide) exhibit amphoterismamphoterism
, in chemistry, the property of certain substances of acting either as acids or as bases depending on the reaction in which they are involved. Many hydroxide compounds are amphoteric.
..... Click the link for more information. , having either acidic or basic properties depending on the reaction in which they are involved. The hydroxides of some nonmetallic elements are acidic; the hydroxide of sulfur, S(OH)6, spontaneously loses two molecules of water to form sulfuric acid, H2SO4. Ammonium hydroxide, NH4OH, is a weak base known only in the solution that is formed when the gas ammoniaammonia,
chemical compound, NH3, colorless gas that is about one half as dense as air at ordinary temperatures and pressures. It has a characteristic pungent, penetrating odor.
..... Click the link for more information. , NH3, dissolves in water.
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Compound containing the OH- group; the hydroxides of metals are usually bases and those of nonmetals are usually acids; a hydroxide can be organic or inorganic.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
1. a base or alkali containing the ion OH--
2. any compound containing an -OH group
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005