Perbromic acid

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Perbromic acid
IUPAC name Perbromic acid[note 1]
Other names Bromic(VII) acid
Hydroxy-λ7-bromanetrione
Hydroxidotrioxidobromine
Identifiers
InChI InChI=1/BrHO4/c2-1(3,4)5/h(H,2,3,4,5)
InChIKey LLYCMZGLHLKPPU-UHFFFAOYAZ
Standard InChI InChI=1S/BrHO4/c2-1(3,4)5/h(H,2,3,4,5)
Standard InChIKey LLYCMZGLHLKPPU-UHFFFAOYSA-N
CAS number [19445-25-1]
ChemSpider 167074
Properties[2]
Chemical formula HBrO4
Molar mass 144.91 g mol−1
Acidity (pKa) < 0
Related compounds
Other perhalic acids Perchloric acid
Periodic acid
Other compounds Hydrobromic acid
Hypobromous acid
Bromous acid
Bromic acid
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Perbromic acid, HBrO4, is an oxoacid of bromine. It is a strong acid that is not known as a molecular species.[2][3][4]

Preparation

Perbromic acid is prepared by ion exchange of a solution of sodium perbromate.[4][5][6] The acid can be concentrated up to 6 M (55%) by evaporation of water under reduced pressure: more concentrated solutions can be prepared, but are unstable.[2][3]

Properties

The properties of perbromic acid are very similar to those of perchloric acid.[2][4] It is a strong acid, completely dissociated in aqueous solution.[4] A solid hydrate, believed to be HBrO4·2H2O, has been prepared:[2][3] by comparison with the perchloric acid azeotrope,[7] also of composition HClO4·2H2O (71.6% HClO4), this should almost certainly be formulated as [(H2O)2H]+[BrO4].

Dilue solutions of perbromic acid are kinetically quite inert in oxidation reactions.[2][3] Hence, unreacted bromate can be removed from perbromate preparations by reaction with 1.5 M hydrobromic acid.[8] At concentrations of 3 M, the acid will attack stainless steel; at 6 M, it will oxidize chloride to chlorine and Mn2+ to permanganate, while the 12 M solution reacts explosively with cellulose.[2][3][4]

Notes and references

Notes

  1. Perbromic acid is a retained name in IUPAC nomenclature.[1]

References

  1. Nomenclature of Inorganic Chemistry; IUPAC Recommendations 2005; Royal Society of Chemistry: Cambridge, 2005; p 287. ISBN 0-85404-438-8, <http://www.iupac.org/publications/books/rbook/Red_Book_2005.pdf>.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Greenwood, Norman N.; Earnshaw, A. Chemistry of the Elements; Pergamon: Oxford, 1984; pp 1020–22. ISBN 0-08-022057-6.
  3. 3.0 3.1 3.2 3.3 3.4 Cotton, F. Albert; Wilkinson, Geoffrey Advanced Inorganic Chemistry, 5th ed.; Wiley-Interscience: New York, 1988; pp 568–69. ISBN 0-471-84997-9.
  4. 4.0 4.1 4.2 4.3 4.4 Ukeles, S. D.; Freiberg, M. Bromine, Inorganic Compounds. In Kirk-Othmer Encyclopedia of Chemical Technology; John Wiley: New York, 2002. DOI: 10.1002/0471238961.021815131001031.
  5. Appelman, Evan H. Perbromic acid and perbromates: synthesis and some properties. Inorg. Chem. 1969, 8 (2), 223–27. DOI: 10.1021/ic50072a008.
  6. Appelman, E. H. Perbromic acid and potassium perbromate. Inorg. Synth. 1972, 13, 1–9. DOI: 10.1002/9780470132449.ch1.
  7. Olovsson, Ivar Hydrogen-Bond Studies. XXIX. Crystal Structure of Perchloric Acid Dihydrate, H5O2+ClO4. J. Chem. Phys. 1968, 49 (3), 1063–67. DOI: 10.1063/1.1670193.
  8. Appelman, Evan H. The Synthesis of Perbromates. J. Am. Chem. Soc. 1968, 90 (7), 1900–1. DOI: 10.1021/ja01009a040.

External links

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