chloric acid

Chloric acid
Other names	Chloric(V) acid
Identifiers
CAS number	7790-93-4
Properties
Molecular formula	HClO3
Molar mass	84.45914 g mol−1
Appearance	colourless solution
Density	ca. 1 g/ml, solution
Solubility in water	>40 g/100 ml (20 °C)
Acidity (pKa)	ca. −1
Structure
Molecular shape	pyramidal
Hazards
MSDS	External MSDS
Main hazards	Oxidant
Related Compounds
Other anions	bromic acid iodic acid
Other cations	ammonium chlorate sodium chlorate potassium chlorate
Related compounds	hydrochloric acid hypochlorous acid chlorous acid perchloric acid
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Chloric acid, HClO₃, is an oxoacid of chlorine, and the formal precursor of chlorate salts. It is almost a strong acid (pK_a ≈ −1) and oxidising agent.

It is prepared by the reaction of sulfuric acid with barium chlorate, the insoluble barium sulfate being removed by precipitation:

Ba(ClO₃)₂ + H₂SO₄ → 2HClO₃ + BaSO₄

Another method is the heating of hypochlorous acid, of which productions include chloric acid and hydrogen chloride:

3HClO → HClO₃ + 2 HCl

It is stable in cold aqueous solution up to a concentration of approximately 30%, and solution of up to 40% can be prepared by careful evaporation under reduced pressure. Above these concentrations, and on warming, chloric acid solutions decompose to give a variety of products, for example:

8HClO₃ → 4HClO₄ + 2H₂O + 2Cl₂ + 3 O₂

3HClO₃ → HClO₄ + H₂O + 2 ClO₂

The decomposition is controlled by kinetic factors: indeed, chloric acid is never thermodynamically stable with respect to disproportionation.

See also

• Hypochlorous acid
• Chlorous acid
• Perchloric acid
• Bromic acid
• Iodic acid

References

• Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4. 
• King, R. B. (Ed.) (1994) Encyclopedia of Inorganic Chemistry, Vol. 2, p. 658. Chichester:Wiley. ISBN 0-471-93620-0

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