Chloric acid

Chloric acid
Other names Chloric(V) acid
Identifiers
CAS number	7790-93-4
ChemSpider	18513
Jmol-3D images	Image 1
SMILES O=Cl(=O)O
InChI InChI=1/ClHO3/c2-1(3)4/h(H,2,3,4) Key: XTEGARKTQYYJKE-UHFFFAOYAG
Properties
Molecular formula	HClO3
Molar mass	84.45914 g mol−1
Appearance	colourless solution
Density	1 g/mL, solution (approximate)
Solubility in water	>40 g/100 ml (20 °C)
Acidity (pKa)	ca. −1
Structure
Molecular shape	pyramidal
Hazards
MSDS	External MSDS
Main hazards	Oxidant, Corrosive
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 references

Chloric acid, HClO₃, is an oxoacid of chlorine, and the formal precursor of chlorate salts. It is a strong acid (pK_a ≈ −1) and oxidizing 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 also produced by the reaction of sulfuric acid with potassium chlorate in the combustion of sugar using potassium chlorate, sulfuric acid, and sugar.

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.

Chloric acid is a dangerously powerful oxidizing agent and will cause most organics and flammables to deflagrate on contact. For example a mixture of potassium chlorate and sugar will burn when concentrated sulfuric acid is added due to chloric acid production. Because sulfur tends to contain acidic impurities, it will form highly unstable mixtures with potassium chlorate due to chloric acid being produced.

Chloric Acid produced from the addition of concentrated sulfuric acid can decompose explosively producing a variety of products such as oxygen, chlorine, and chlorine oxides

See also

• Hypochlorous acid
• Chlorous acid
• Perchloric acid
• Bromic acid
• Iodic acid
• Oxidizing acid
• Chlorate

References

• Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Oxford: Butterworth-Heinemann. ISBN 0080379419. 
• R. Bruce King, ed (1994). "Chloric acid". Encyclopedia of Inorganic Chemistry. 2. Chichester: Wiley. p. 658. ISBN 0-471-93620-0.