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Chlorate
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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 followed by a roman numeral in parenthesis, e.g. chlorate(VII), refers to a particular oxyanion of chlorine.
As predicted by VSEPR, chlorate anions have trigonal pyrimidal structures.
Chlorates are powerful oxidizers and should be kept away from organics or easily oxidized materials.
Chlorates were once widely used in pyrotechnics, though their use has fallen due to their instability.
Most pyrotechnic applications which used chlorates in the past now use perchlorates instead.
l chlorates can be prepared by adding chlorine to hot metal hydroxides, for example, KClO3:
- 3Cl2 + 6KOH ? 5KCl + KClO3 + 3H2O
In this reaction chlorine undergoes disproportionation, both reduction and oxidation.
Discussion
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Encyclopedia
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 followed by a roman numeral in parenthesis, e.g. chlorate(VII), refers to a particular oxyanion of chlorine.
As predicted by VSEPR, chlorate anions have trigonal pyrimidal structures.
Chlorates are powerful oxidizers and should be kept away from organics or easily oxidized materials.
Chlorates were once widely used in pyrotechnics, though their use has fallen due to their instability.
Most pyrotechnic applications which used chlorates in the past now use perchlorates instead.
Preparation
Laboratory
Metal chlorates can be prepared by adding chlorine to hot metal hydroxides, for example, KClO3:
- 3Cl2 + 6KOH ? 5KCl + KClO3 + 3H2O
In this reaction chlorine undergoes disproportionation, both reduction and oxidation. Chlorine, oxidation number 0, forms chloride Cl- (oxidation number -1) and chlorate(V) ClO3- (oxidation number +5). Reaction of dilute aqueous sodium hydroxide with chlorine produces the chloride and hypochlorite (oxidation number +1).
Industrial
The industrial scale synthesis for sodium chlorate starts from aqueous sodium chloride solution (brine) rather than chlorine gas. If equipment for electrolysis does not prevent a mixing of the chlorine evolved and the sodium hydroxide is as described in chlorine, then the disproportionation reaction described above occurs. The heating of the reactants to 50-70°C is performed by the electrical power used for electrolysis.
Compounds (salts)
Examples of chlorates include:
Other oxyanions
If a Roman numeral in brackets follows the word "chlorate", this indicates the oxyanion contains chlorine in the indicated oxidation state, namely:
| Common name | Stock name | Oxidation state | Formula |
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| Hypochlorite | Chlorate(I) | +1 | ClO- | | Chlorite | Chlorate(III) | +3 | ClO2- | | Chlorate | Chlorate(V) | +5 | ClO3- | | Perchlorate | Chlorate(VII) | +7 | ClO4- |
Using this convention, "chlorate" means any chlorine oxyanion. Commonly, "chlorate" refers only to chlorine in the +5 oxidation state.
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