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(klōr`īd, klôr`–), chemical compound containing chlorine. Most chlorides are salts that are formed either by direct union of chlorine with a metal or by reaction of hydrochloric acid (a water solution of hydrogen chloridehydrogen chloride,
chemical compound, HCl, a colorless, poisonous gas with an unpleasant, acrid odor. It is very soluble in water and readily soluble in alcohol and ether. It fumes in moist air. It is not flammable, and the liquid is a poor conductor of electricity.
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) with a metal, a metal oxide, or an inorganic base. Chloride salts include sodium chloridesodium chloride,
NaCl, common salt. Properties

Sodium chloride is readily soluble in water and insoluble or only slightly soluble in most other liquids. It forms small, transparent, colorless to white cubic crystals.
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 (common salt), potassium chloridepotassium chloride,
chemical compound, KCl, a colorless or white, cubic, crystalline compound that closely resembles common salt (sodium chloride). It is soluble in water, alcohol, and alkalies.
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, calcium chloridecalcium chloride,
CaCl2, chemical compound that is crystalline, lumpy, or flaky, is usually white, and is very soluble in water. The anhydrous compound is hygroscopic; it rapidly absorbs water and is used to dry gases by passing them through it.
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, and ammonium chlorideammonium chloride
, chemical compound, NH4Cl, a white or colorless, odorless, water-soluble, cubic crystalline salt with a biting taste, commonly known as sal ammoniac.
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. Most chloride salts are readily soluble in water, but mercurous chloridemercurous chloride,
 mercury (I) chloride,
or calomel,
chemical compound, Hg2Cl2, a white crystalline powder, very slightly soluble in water.
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 (calomel) and silver chloridesilver chloride,
chemical compound, AgCl, a white cubic crystalline solid. It is nearly insoluble in water but is soluble in a water solution of ammonia, potassium cyanide, or sodium thiosulfate ("hypo").
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 are insoluble, and lead chloride is only slightly soluble. Some chlorides, e.g., antimony chloride and bismuth chloride, decompose in water, forming oxychlorides. Many metal chlorides can be melted without decomposition; two exceptions are the chlorides of gold and platinum. Most metal chlorides conduct electricity when fused or dissolved in water and can be decomposed by electrolysiselectrolysis
, passage of an electric current through a conducting solution or molten salt that is decomposed in the process. The Electrolytic Process

The electrolytic process requires that an electrolyte, an ionized solution or molten metallic salt, complete an
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 to chlorine gas and the metal. Chlorine forms compounds with the other halogens and with oxygen; when chlorine is the more electronegative element in the compound, the compound is called a chloride. Thus, compounds with bromine and iodine are bromine chloride, BrCl, and iodine chloride, ICI, but compounds with oxygen or fluorine (which are more electronegative than chlorine) are oxides (e.g., chlorine dioxide, ClO2) or fluorides (e.g., chlorine fluoride, ClF) respectively. Many organic compounds contain chlorine, as is indicated by common names such as carbon tetrachloride, methylene chloride, and methyl chloride. However, in the nomenclature system for organic chemistry adopted by the International Union of Pure and Applied Chemistry (IUPAC), the presence in a compound of chlorine bonded to a carbon atom is indicated by the prefix or infix chloro; thus, carbon tetrachloride is tetrachloromethane, methylene chloride is dichloromethane, and methyl chloride is chloromethane.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



any one of a group of compounds of chlorine with all elements possessing lower electronegativity, that is, with all metals and nonmetals except oxygen and fluorine. (The chlorides of nitrogen constitute another exception; they are named thus, although the electronegativity of nitrogen is greater than that of chorine.)

Metal chlorides (or salts of hydrochloric acid) are solids, most of which melt or vaporize without decomposition. Most are readily soluble in water except AgCl, CuCl, HgCl2, TlCl, and PbCl2, which are poorly soluble. The chlorides of alkali and alkaline-earth metals are neutral. Solutions of chlorides of other metals are acidic as a result of hydrolysis; for example, AlCl3 + 3H2O = Al(OH)3 + 3HCl.

Chlorides of nonmetals may be gases (HCl), liquids (PCl3), or solids (PCl5). Such compounds are hydrolyzed by water; for example, PCl5 + 4H2O = H3PO4 + 5HCl.

Sodium chloride, potassium chloride, magnesium chloride, and calcium chloride are common in nature (see).

For information on the properties, production, and uses of chlorides, seePOTASSIUM CHLORIDE; SODIUM CHLORIDE; MAGNESIUM CHLORIDE; CALCIUM CHLORIDE; and TITANIUM HALIDE.

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


A compound which is derived from hydrochloric acid and contains the chlorine atom in the -1 oxidation state.
In general, any binary compound containing chloride.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


1. any salt of hydrochloric acid, containing the chloride ion Cl--
2. any compound containing a chlorine atom, such as methyl chloride (chloromethane), CH3Cl
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
In a marine environment, in addition to its presence in original mix, the chloride ions penetrate into the concrete either from sea water or sea winds carrying sea salts and reacts with the hydrated cement products which produces complex compounds including Friedels salt which are leachable and expansive in nature.
The fine particles of blast furnace slag improved the chloride ion penetration resistance but reduced the initial compressive and flexural strengths.
(2) The higher the amount of calcium stearate added to the concrete, the lower the chloride ion infiltration.
The diffusion theory based on Fick's second law can be used to predict the penetration of chloride ions through concrete structures.
Wachira, "Diffusivity of chloride ion in mortar cubes made using ordinary portland and portland pozzolana cements," IOSR Journal of Applied Chemistry, vol.
Water soluble chloride ion (Cl-) tests were performed on six concrete powder samples extracted from the core samples, between 0 to 100mm below the surface of the concrete for the beams, and 0 to 25mm for the columns (due to short length of cores).
Caption: Figure 6: Memristor system's responses to the voltage stimulus reported in the inset of Figure 1 in which one device undergoes a performance degeneration inducted by a progressive lowering of chloride ion content in the polyelectrolyte: black squares represent the curve obtained in the 1[degrees] iteration; red circles 2[degrees] iteration; green triangles 3[degrees] iteration; blues triangles 4[degrees] iteration; light-blue squares 5[degrees] iteration; magenta triangles 6[degrees] iteration; and yellow triangles 7[degrees] iteration.
The cause of the presence of the chloride ions in concrete takes place in two ways: one is from the pure components of concrete, such as water, aggregate, and cement, and the other is the intrusion of the chloride ions from atmosphere.
Role of calcium as well as chloride ion in stabilization of amylase structure had been reported earlier by many workers [31].
Oxidation of chloride ion in [C.sub.3][OHmimBF.sub.4] was carried out at a lower electric potential of the oxidation reaction occurrence; the oxidation peak significantly decreases to 1.0 V.
The following tests serve as a means of indirectly assessing the permeability of concrete mixes: the American Association of State Highway and Transportation Officials' (AASHTO) Standard Metbod of Test for Rapid Determination of the Chloride Permeability of Concrete, AASHTO T277, and the American Society for Testing and Materials' (ASTM) Standard lest Method for Electrical Indication of Concrete's Ability to Resist Chloride Ion Penetration, ASTM CI202.