Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
Related to chlorate: sodium chlorate, potassium chlorate


(klōr`āt, klôr`–) and


(pərklōr`āt, –klôr`–), saltssalt,
chemical compound (other than water) formed by a chemical reaction between an acid and a base (see acids and bases). Characteristics and Classification of Salts

The most familiar salt is sodium chloride, the principal component of common table salt.
..... Click the link for more information.
 of chloric acid, HClO3, and perchloric acid, HClO4, respectively.

Chloric Acid and Its Salts

Chloric acid, HClO3·7H2O, is a colorless substance that occurs only in solution. It is a strong acid and a strong oxidizing agent that decomposes if heated above 40°C;. Under certain conditions it forms oxygen, water, and the explosive gas chlorine dioxide, ClO2; under other conditions it forms perchloric acid and hydrochloric acid.

Formation of Chlorates

A chlorate may be formed (together with the corresponding chloride) by heating the hypochlorite; e.g., 3Ca(ClO)2→Ca(ClO3)2+2CaCl2. This reaction takes place when chlorine gas is passed into a hot aqueous solution of a metal hydroxide; the hypochlorite is formed and decomposes almost immediately. Commercially, a chlorate is derived when a hot aqueous metal chloride solution is decomposed by electrolysis, forming chlorine gas at the anode and metal hydroxide at the cathode (with evolution of hydrogen); the chlorine reacts with the hydroxide to form the hypochlorite, which decomposes to form the chlorate.

Commercial Uses of Chlorates

The most industrially important chlorate is potassium chlorate, or chlorate of potash, KClO3; sodium chlorate, or chlorate of soda, NaClO3, is also used. Potassium chlorate is a colorless crystalline substance that melts at 356°C; and decomposes violently at about 400°C;. It is a powerful oxidizing agent and is used in making explosives and matches; a mixture of potassium chlorate with phosphorus, sulfur, or any of numerous organic compounds (e.g., charcoal or sugar) explodes upon friction or percussion. When a chlorate is heated, oxygen is evolved, often explosively, and the chloride is formed; e.g., 2KClO3→2KCl+3O2. The reaction proceeds controllably at lower temperatures if a catalyst, e.g., manganese dioxide, is used; this provides a convenient source of oxygen. If the chlorate is heated carefully at a lower temperature so that no oxygen is given off, the perchlorate and chloride are formed; e.g., 4KClO3→3KClO4+KCl.

Perchloric Acid and Its Salts

Perchloric acid, HClO4, is a volatile, unstable, colorless liquid that is a strong, corrosive acid and a powerful oxidizing agent, especially when hot. It explodes if heated to about 90°C; or on contact with combustible materials. The monohydrate, HClO4·H2O, is fairly stable and forms needlelike crystals that melt at 50°C;. It explodes if heated to 110°C;. The dihydrate, HClO4·2H2O, is a stable liquid that boils at 200°C;.

Formation of Perchlorates

Perchloric anhydride, or chlorine heptoxide, Cl2O7, is a colorless, oily liquid that boils at 82°C; without exploding but that may be detonated by shock; it can be prepared by adding phosphorus pentoxide to cold perchloric acid. The perchlorate free radical (chlorine tetroxide, ClO4) can be prepared by adding bromine to silver perchlorate; it is extremely reactive and unstable.

Commercial Uses of Perchlorates

Perchlorates are safer to handle than chlorates; they are more stable when exposed to heat or shock. Potassium perchlorate, KClO4, is perhaps most widely used, e.g., in matches, fireworks, and explosives. It is a colorless crystalline substance that melts at about 610°C;.

The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



any one of a group of salts of chloric acid, HClO3. Chlorates are crystalline compounds that are stable at ordinary temperatures but decompose upon heating or in the presence of catalysts with the liberation of oxygen. Most are readily soluble in water and some organic solvents. Chlorates form explosive mixtures with organic and readily oxidizable compounds. Sodium chlorate, potassium chlorate, calcium chlorate, and magnesium chlorate are produced on an industrial scale.

Potassium chlorate, KClO3, has a density of 2.344 g/cm3 and a melting point of 370°C. It was first produced in 1786 by C. L. Berthollet by the addition of chlorine to a concentrated solution of potassium hydroxide. Its solubility in water is 32.4 g/liter (g/l) at 0°C, 170.5 g/l at 50°C, and 437 g/l at 100°C. Potassium chlorate is nonhygroscopic. It decomposes at about 400°C with the liberation of oxygen; however, in the presence of catalysts, such as MnO2 and Fe2O3, it decomposes at about 150°–200°C. Chemically pure potassium chlorate explodes at 550°–600°C, and in a mixture with sulfur, phosphorus, and many organic compounds, it explodes upon impact or friction. Its explosiveness increases in the presence of bromates and ammonium salts. Potassium chlorate is produced by the exchange decomposition of calcium chlorate or sodium chlorate with KCl. It is used in the production of matches and pyrotechnical substances.

Sodium chlorate, NaClO3, has a density of 2.49 g/cm3 at 15°C and a melting point of 248°C. Its solubility in water is 612 g/l at 0°C, 870 g/l at 50°C, and 1,190 at g/l at 100°C. Slightly hygroscopic, it is similar to potassium chlorate in chemical properties. It is produced by the electrolysis of aqueous solutions of NaCl in cells without diaphragms. It is used to obtain chlorine dioxide and in the production of other chlorates and perchlorates.

Calcium chlorate, Ca(ClO3)2, is a very hygroscopic salt. With water it forms the crystal hydrates Ca(ClO3) · nH2O, where n ranges from 1 to 6. It disperses in the air. Calcium chlorate is produced by the chlorination of milk of lime:

6Ca(OH)2 + 6Cl2 = Ca(ClO3)2 + 5CaCl2 + 6H2O

It is used as an intermediate in the production of potassium chlorate; it is also used in agriculture as a herbicide and defoliant.

Magnesium chlorate, Mg(ClO3)2, is a very hygroscopic salt. With water it forms crystal hydrates, such as Mg(ClO3)2 · 6H2O. Anhydrous magnesium chlorate has not been obtained. Magnesium chlorate disperses in the air. The crystal hydrate is obtained by melting sodium chlorate with bischofite:

2NaClO3 + MgCl2 · 6H2O = Mg(ClO3)2 · 6H2O + 2NaCl

It is flammable and explosive. Magnesium chlorate is used for the preharvest removal of leaves from the cotton plant and for the desiccation of sunflower, rice, seed plants of leguminous crops, and sugar-beet transplantations.

Chlorates have low toxicity. Chronic chlorate poisoning results from internal consumption or the breathing of chlorate dust.


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


(inorganic chemistry)
A negative ion derived from chloric acid.
A salt of chloric acid.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


any salt of chloric acid, containing the monovalent ion ClO3--
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Superior has approved expansions of the sodium chlorate production capacity at the Buckingham, Quebec and Valdosta, Georgia sodium chlorate facilities.
What has been the historical and current value trends in the sodium chlorate market?
"A recent study by the Chemischen und Veterinaruntersuchungsamter (CVUA) in Germany discovered higher than expected chlorate levels in some fresh fruit and vegetables, from a variety of origins, and we have detected similarly high levels in products tested by our scientists here at Fera."
The arrested drivers told their investigators that the potassium and ammonium chlorate were packed with wires and detonators into vehicles inside the compound.
Passing oxygen without chlorate, even in the presence of a catalyst, does not induce decomposition because molecular oxygen is stable under these conditions, and it is very difficult to decompose the dye at room temperature.
The most effective treatment was a combination of nitro and chlorate compounds.
Sodium chlorate acts on metabolism enzymes in the cell which attach sulfate groups to proteins.
KABUL (PAN): The International Security Assistance Force (ISAF) on Thursday congratulated Afghan border and customs police on their momentousseizure of 16,000 kilograms of ammonium chlorate in the Spin Boldak district odf southern Kandahar province.
The substance in the pipes was made of chlorate and sugar, but experts have not determined how powerful the explosive mixture was, Redlich said.
Chlorate and a certain class of chemicals called "nitro compounds" were shown to substantially reduce or eliminate the important foodborne pathogens Salmonella and Escherichia coli O157:H7.
The European Commission condemned four groups of manufacturers, on 28 March, for their agreements to allocate share volumes and fix prices for sodium chlorate, an oxidising agent used mainly to whiten paper.
GACL expands hydrogen peroxide plant and gears up to manufacture Sodium Chlorate Crystal