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The chlorate ion
Structure and bonding in the chlorate ion

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. 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.

Examples of chlorates include:


Metal chlorates can be prepared by adding chlorine to hot metal hydroxides, for example, KClO3:

3Cl2 + 6KOH → 5KCl + KClO3 + 3H2O

The industrial scale synthesis for sodium chlorate starts from sodium chloride. {If the electrolysis is not done with the method described at chlorine, but a mixing of the chlorine evolved and the sodium hydroxide is allowed, the reaction mentioned above takes place. The heating to 50-70°C is done by the electrical power applied for electrolysis.[citation needed]

Stock notation

If a Roman numeral in brackets follow the word "chlorate", this refers to the oxyanion containing chlorine in the respective oxidation state, namely:

Common name Stock name Oxidation state Formula
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. However, Stock notation for chlorine is quite uncommon, and "chlorate" typically refers only to the +5 oxidation state.


de:Chlorat gl:Clorato he:כלוראט no:Klorat nn:Klorat