chloric acid
{{chembox
| Name = Chloric acid
| ImageFile = Chloric-acid-2D.png
| ImageName = Chloric acid
| ImageFile1 = Chloric-acid-3D-vdW.png
| ImageName1 = Chloric acid
| OtherNames = Chloric(V) acid
|Section1={{Chembox Identifiers
| ChemSpiderID = 18513
| PubChem = 19654
| EC_number = 232-233-0
| UNNumber = 2626
| UNII = Z0V9L75H3K
| InChI = 1/ClHO3/c2-1(3)4/h(H,2,3,4)
| SMILES = O[Cl+2]([O-])[O-]
| InChIKey = XTEGARKTQYYJKE-UHFFFAOYAG
| CASNo = 7790-93-4
}}
|Section2={{Chembox Properties
| Formula = HClO3
| MolarMass = 84.45914 g mol−1
| Appearance = colourless solution
| Density = 1 g/mL, solution (approximate)
| Solubility = >40 g/100 ml (20 °C)
| ConjugateBase = Chlorate
}}
|Section3={{Chembox Structure
| MolShape = pyramidal
| Dipole =
}}
|Section7={{Chembox Hazards
| ExternalSDS =
| MainHazards = Oxidant, Corrosive
| GHSPictograms = {{GHS03}}{{GHS05}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|271|314}}
| PPhrases = {{P-phrases|210|220|221|260|264|280|283|301+330+331|303+361+353|304+340|305+351+338|306+360|310|321|363|370+378|371+380+375|405|501}}
| NFPA-H = 3
| NFPA-F = 0
| NFPA-R = 2
| NFPA-S = OX
}}
|Section8={{Chembox Related
| OtherAnions = bromic acid
iodic acid
| OtherCations = ammonium chlorate
sodium chlorate
potassium chlorate
| OtherCompounds = hydrochloric acid
hypochlorous acid
chlorous acid
perchloric acid
}}
}}
Chloric acid, HClO3, is an oxoacid of chlorine, and the formal precursor of chlorate salts. It is a strong acid (pKa ≈ −2.7) and an oxidizing agent.
Properties
{{unreferenced section|date=December 2024}}
Chloric acid is thermodynamically unstable with respect to disproportionation.
Chloric acid 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, chloric acid solutions decompose to give a variety of products, for example:
:{{chem2|8 HClO3 -> 4 HClO4 + 2 H2O + 2 Cl2 + 3 O2}}
:{{chem2|3 HClO3 -> HClO4 + H2O + 2 ClO2}}
Hazards
Chloric acid is a powerful oxidizing agent. Most organics and flammables will deflagrate on contact.{{cn|date=December 2024}}
Production
It may be produced from barium chlorate through its reaction with sulfuric acid, which results in a solution of chloric acid and insoluble barium sulfate precipitate:{{cite book |last1=Brauer |first1=Georg |last2=Schmeisser |first2=M. |editor1-last=Riley |editor1-first=Reed F. |title=Handbook of Preparative Inorganic Chemistry |date=1963 |publisher=Academic Press |location=New York, London |isbn=9780121266011 |pages=312-313 |edition=2nd |url=https://archive.org/details/Handbook_of_Preparative_Inorganic_Chemistry_1_2_Brauer/page/n335/mode/2up |access-date=6 December 2024 |ref=Brauer |chapter=5. Chlorine, Bromine, Iodine}}
:{{chem2|Ba(ClO3)2 + H2SO4 -> 2 HClO3 + BaSO4}}
The chlorate must be dissolved in boiling water and the acid should be somewhat diluted in water and heated before mixing.
Another method which can be used to produce solutions up to 10% concentration is by the use of cation exchange resins and a soluble salt such as {{chem2|NaClO3}}, where the Na+ cation will exchange with H+.
Another method is the heating of hypochlorous acid, producing chloric acid and hydrogen chloride:{{cn|date=December 2024}}
:{{chem2|3 HClO -> HClO3 + 2 HCl}}
Any way it is produced, the acid may be concentrated up to 40% in a vacuum dessicator over {{chem2|H2SO4}}.
See also
References
Additional Information
- {{Greenwood&Earnshaw}}
- {{cite encyclopedia |editor= R. Bruce King|encyclopedia= Encyclopedia of Inorganic Chemistry|title= Chloric acid|year= 1994|publisher= Wiley|volume= 2|location= Chichester|isbn= 0-471-93620-0|page= 658}}
{{Hydrogen compounds}}
{{Chlorates}}