Calcium chlorate is the

calcium Calcium is a chemical element with the 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 t ...

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quanti ...

chloric acid Chloric acid, H Cl O3, is an oxoacid of chlorine, and the formal precursor of chlorate salts. It is a strong acid ( p''K''a ≈ −2.7 (''***note: pKa not in agreement with properties in chem box at right'')) and oxidizing agent. Properties Chlo ...

, with the

chemical formula In chemistry, 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, ...

Ca(ClO₃)₂. Like other

chlorate The chlorate anion has the formula ClO3-. In this case, the chlorine atom is in the +5 oxidation state. "Chlorate" can also refer to chemical compounds containing this anion; chlorates are the salts of chloric acid. "Chlorate", when followe ...

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 ). In other words, an oxid ...

Production

Calcium chlorate is produced by passing

chlorine Chlorine is a chemical element with the 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 them. Chlorine is ...

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 or slaked with water. It has m ...

in water, producing

calcium hypochlorite Calcium hypochlorite is an inorganic compound with formula Ca(OCl)2. It is the main active ingredient of commercial products called bleaching powder, chlorine powder, or chlorinated lime, used for water treatment and as a bleaching agent. Th ...

, which

disproportionates In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can b ...

when heated with excess chlorine to give calcium chlorate and

calcium chloride Calcium chloride is an inorganic compound, a 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 calcium hydroxide. Cal ...

: : 6 Ca(OH)₂ + 6 Cl₂ → Ca(ClO₃)₂ + 5 CaCl₂ + 6 H₂O This is also the first step of the

Liebig process Justus Freiherr von Liebig (12 May 1803 – 20 April 1873) was a German scientist who made major contributions to agricultural and biological chemistry, and is considered one of the principal founders of organic chemistry. As a professor at th ...

for the manufacture of

potassium chlorate Potassium chlorate is a compound containing potassium, chlorine and oxygen, with the molecular formula KClO3. In its pure form, it is a white crystalline substance. After sodium chlorate, it is the second most common chlorate in industrial use. It ...

. In theory, electrolysis of hot calcium chloride solution will give chlorate, analogous to the process used for the manufacture of

sodium chlorate Sodium chlorate is an inorganic compound with the chemical formula Na ClO3. It is a white crystalline powder that is readily soluble in water. It is hygroscopic. It decomposes above 300 °C to release oxygen and leaves sodium chloride. Sever ...

. 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. This definition can be recalled by using the mnemonic ''CCD'' for ''Cathode Current Departs''. A conventional current describes the direction i ...

, 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 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 react to give a precipitate of

calcium sulfate Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO4 and related hydrates. In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. One particular hydrate is better known as plaster of Paris, ...

and

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 Ammonium chlorate is an inorganic compound with the formula NH4ClO3. It is obtained by neutralizing chloric acid with either ammonia or ammonium carbonate, or by precipitating barium, strontium or calcium Calcium is a chemical element wi ...

Uses

Calcium chlorate has been used as an herbicide, like

. Calcium chlorate is occasionally used in

pyrotechnics Pyrotechnics is the science and craft of creating such things as fireworks, safety matches, oxygen candles, Pyrotechnic fastener, explosive bolts and other fasteners, parts of automotive airbags, as well as gas-pressure blasting in mining, quarry ...

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

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...

) limit its utility in these applications.

References

{{Chlorates Chlorates Calcium compounds Oxidizing agents