Difference between revisions of "Perbromic acid"
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| − | '''Perbromic acid''', HBrO<sub>4</sub>, is an [[oxoacid]] of [[bromine]]. It is a [[strong acid]] that is not known as a molecular species.<ref name="G&E"/><ref name="Kirk-Othmer">{{Kirk-Othmer | first1 = S. D. | last1 = Ukeles | first2 = M. | last2 = Freiberg | contribution = Bromine, Inorganic Compounds | doi = 10.1002/0471238961.021815131001031 | year = 2002}}.</ref> | + | '''Perbromic acid''', HBrO<sub>4</sub>, is an [[oxoacid]] of [[bromine]]. It is a [[strong acid]] that is not known as a molecular species.<ref name="G&E"/><ref name="C&W">{{Cotton&Wilkinson5th|pages=568–69}}.</ref><ref name="Kirk-Othmer">{{Kirk-Othmer | first1 = S. D. | last1 = Ukeles | first2 = M. | last2 = Freiberg | contribution = Bromine, Inorganic Compounds | doi = 10.1002/0471238961.021815131001031 | year = 2002}}.</ref> |
==Preparation== | ==Preparation== | ||
| − | Perbromic acid is prepared by [[ion exchange]] of a solution of [[sodium perbromate]].<ref name="Kirk-Othmer"/><ref>{{citation | first = Evan H. | last = Appelman | title = Perbromic acid and perbromates: synthesis and some properties | journal = Inorg. Chem. | volume = 8 | issue = 2 | pages = 223–27 | year = 1969 | doi = 10.1021/ic50072a008}}.</ref><ref>{{citation | first = E. H. | last = Appelman | title = Perbromic acid and potassium perbromate | journal = Inorg. Synth. | year = 1972 | volume = 13 | pages = 1–9 | doi = 10.1002/9780470132449.ch1}}.</ref> 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.<ref name="G&E"/> | + | Perbromic acid is prepared by [[ion exchange]] of a solution of [[sodium perbromate]].<ref name="Kirk-Othmer"/><ref>{{citation | first = Evan H. | last = Appelman | title = Perbromic acid and perbromates: synthesis and some properties | journal = Inorg. Chem. | volume = 8 | issue = 2 | pages = 223–27 | year = 1969 | doi = 10.1021/ic50072a008}}.</ref><ref>{{citation | first = E. H. | last = Appelman | title = Perbromic acid and potassium perbromate | journal = Inorg. Synth. | year = 1972 | volume = 13 | pages = 1–9 | doi = 10.1002/9780470132449.ch1}}.</ref> 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.<ref name="G&E"/><ref name="C&W"/> |
==Properties== | ==Properties== | ||
| + | The properties of perbromic acid are very similar to those of [[perchloric acid]].<ref name="G&E"/><ref name="Kirk-Othmer"/> It is a [[strong acid]], completely dissociated in aqueous solution.<ref name="Kirk-Othmer"/> A solid hydrate, believed to be HBrO<sub>4</sub>·2H<sub>2</sub>O, has been prepared:<ref name="G&E"/><ref name="C&W"/> by comparison with the perchloric acid [[azeotrope]],<ref>{{citation | first = Ivar | last = Olovsson | title = Hydrogen-Bond Studies. XXIX. Crystal Structure of Perchloric Acid Dihydrate, {{nowrap|H<sub>5</sub>O<sub>2</sub><sup>+</sup>ClO<sub>4</sub><sup>−</sup>}} | journal = J. Chem. Phys. | volume = 49 | issue = 3 | pages = 1063–67 | year = 1968 | doi = 10.1063/1.1670193}}.</ref> also of composition HClO<sub>4</sub>·2H<sub>2</sub>O (71.6% HClO<sub>4</sub>), this should almost certainly be formulated as {{nowrap|[(H<sub>2</sub>O)<sub>2</sub>H]<sup>+</sup>[BrO<sub>4</sub>]<sup>−</sup>}}. | ||
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| + | Dilue solutions of perbromic acid are kinetically quite inert in oxidation reactions.<ref name="G&E"/><ref name="C&W"/> Hence, unreacted [[bromate]] can be removed from perbromate preparations by reaction with 1.5 M [[hydrobromic acid]].<ref>{{citation | title = The Synthesis of Perbromates | first = Evan H. | last = Appelman | journal = J. Am. Chem. Soc. | year = 1968 | volume = 90 | issue = 7 | pages = 1900–1 | doi = 10.1021/ja01009a040}}.</ref> At concentrations of 3 M, the acid will attack [[stainless steel]]; at 6 M, it will oxidize [[chloride]] to [[chlorine]] and Mn<sup>2+</sup> to [[permanganate]], while the 12 M solution reacts explosively with [[cellulose]].<ref name="G&E"/><ref name="C&W"/><ref name="Kirk-Othmer"/> | ||
==Notes and references== | ==Notes and references== | ||
Latest revision as of 09:42, 5 January 2011
| 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 | [] |
| ChemSpider | |
| 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]
Contents
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
- ↑ Perbromic acid is a retained name in IUPAC nomenclature.[1]
References
- ↑ 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>.
- ↑ 2.0 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.
- ↑ 3.0 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.
- ↑ 4.0 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.
- ↑ Appelman, Evan H. Perbromic acid and perbromates: synthesis and some properties. Inorg. Chem. 1969, 8 (2), 223–27. DOI: 10.1021/ic50072a008.
- ↑ Appelman, E. H. Perbromic acid and potassium perbromate. Inorg. Synth. 1972, 13, 1–9. DOI: 10.1002/9780470132449.ch1.
- ↑ 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.
- ↑ Appelman, Evan H. The Synthesis of Perbromates. J. Am. Chem. Soc. 1968, 90 (7), 1900–1. DOI: 10.1021/ja01009a040.
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