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 quant ...
of
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 symbol ...
Ca(ClO
3)
2. Like other
chlorates, 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 i ...
gas through a hot suspension of
calcium hydroxide in water, producing
calcium hypochlorite, which
disproportionates 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.
Ca ...
:
: 6 Ca(OH)
2 + 6 Cl
2 → Ca(ClO
3)
2 + 5 CaCl
2 + 6 H
2O
This is also the first step of the
Liebig process for the manufacture of
potassium chlorate.
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 in wh ...
, preventing the flow of current.
Reactions
When concentrated solutions of calcium chlorate and
potassium chloride are combined, potassium chlorate precipitates:
: Ca(ClO
3)
2 + 2 KCl → 2 KClO
3 + CaCl
2
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(ClO
3)
2 + Na
2CO
3 → 2 NaClO
3 + CaCO
3
On strong heating, calcium chlorate decomposes to give oxygen and calcium chloride:
: Ca(ClO
3)
2 → CaCl
2 + 3 O
2
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
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 ...
in solution:
: Ca(ClO
3)
2 + H
2SO
4 → 2 HClO
3 + CaSO
4
Contact with strong sulfuric acid can result in explosions
[PubChem - 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, like 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 ...
.
Calcium chlorate is occasionally used in pyrotechnics, as an oxidizer and pink flame colorant. Its hygroscopic nature and incompatibility with other common pyrotechnic materials (such as sulfur) limit its utility in these applications.
References
{{Chlorates
Chlorates
Calcium compounds
Oxidizing agents