Calcium chlorate is the

calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

of chloric acid, with the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

Ca(ClO₃)₂. Like other

chlorate Chlorate is the common name of the anion, whose chlorine atom is in the +5 oxidation state. The term can also refer to chemical compounds containing this anion, with Chlorate#Compounds (salts), chlorates being the salt (chemistry), salts of chlo ...

s, it is a strong

oxidizer An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ''electron donor''). In ot ...

Production

Calcium chlorate is produced by passing

chlorine Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...

gas through a hot suspension of

calcium hydroxide Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca( OH)2. It is a colorless crystal or white powder and is produced when quicklime ( calcium oxide) is mixed with water. Annually, approxim ...

in water, producing

calcium hypochlorite Calcium hypochlorite is an inorganic compound with chemical formula , also written as . It is a white solid, although commercial samples appear yellow. It strongly smells of chlorine, owing to its slow decomposition in moist air. This compound is ...

, which disproportionates when heated with excess chlorine to give calcium chlorate and

calcium chloride Calcium chloride is an inorganic compound, a Salt (chemistry), salt with the chemical formula . It is a white crystalline solid at room temperature, and it is highly soluble in water. It can be created by neutralising hydrochloric acid with cal ...

: : 6 Ca(OH)₂ + 6 Cl₂ → Ca(ClO₃)₂ + 5 CaCl₂ + 6 H₂O This is also the first step of the Liebig process for the manufacture of potassium chlorate. In theory,

electrolysis In chemistry and manufacturing, electrolysis is a technique that uses Direct current, direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of c ...

of hot calcium chloride solution will produce the chlorate salt, analogous to the process used for the manufacture of sodium chlorate. In practice, electrolysis is complicated by calcium hydroxide depositing on the

cathode A cathode is the electrode from which a conventional current leaves a polarized electrical device such as a lead-acid battery. This definition can be recalled by using the mnemonic ''CCD'' for ''Cathode Current Departs''. Conventional curren ...

, preventing the flow of current.

Reactions

When concentrated solutions of calcium chlorate and

potassium chloride Potassium chloride (KCl, or potassium salt) is a metal halide salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous crystal appearance. The solid dissolves readily in water, and its solutions have a sa ...

are combined, potassium chlorate precipitates: : Ca(ClO₃)₂ + 2 KCl → 2 KClO₃ + CaCl₂ This is the second step of the Liebig process for the manufacture of potassium chlorate. Solutions of calcium chlorate react with solutions of alkali carbonates to give a precipitate of

calcium carbonate Calcium carbonate is a chemical compound with the chemical formula . It is a common substance found in Rock (geology), rocks as the minerals calcite and aragonite, most notably in chalk and limestone, eggshells, gastropod shells, shellfish skel ...

and the alkali chlorate in solution: : Ca(ClO₃)₂ + Na₂CO₃ → 2 NaClO₃ + CaCO₃ On strong heating, calcium chlorate decomposes to give oxygen and calcium chloride: : Ca(ClO₃)₂ → CaCl₂ + 3 O₂ Cold, dilute solutions of calcium chlorate and

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...

react to give a precipitate of

calcium sulfate Calcium sulfate (or calcium sulphate) is an inorganic salt with the chemical formula . It occurs in several hydrated forms; the anhydrous state (known as anhydrite) is a white crystalline solid often found in evaporite deposits. Its dihydrate ...

and chloric acid in solution: : Ca(ClO₃)₂ + H₂SO₄ → 2 HClO₃ + CaSO₄ Contact with strong sulfuric acid can result in explosionsPubChem - Calcium Chlorate: Experimental Properties
/ref> due to the instability of concentrated chloric acid. Contact with ammonium compounds can also cause violent decomposition due to the formation of unstable ammonium chlorate.

Uses

Calcium chlorate has been used as an

herbicide Herbicides (, ), also commonly known as weed killers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...

, like sodium chlorate. Calcium chlorate is occasionally used in

pyrotechnics Pyrotechnics is the science and craft of creating fireworks, but also includes safety matches, oxygen candles, Pyrotechnic fastener, explosive bolts (and other fasteners), parts of automotive airbags, as well as gas-pressure blasting in mining, q ...

, as an oxidizer and pink flame colorant. Its hygroscopic nature and incompatibility with other common pyrotechnic materials (such as

sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...

) limit its utility in these applications.

References

{{Chlorates Chlorates Calcium compounds Oxidizing agents