Oxoacid
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2008-03-31T15:06:14Z
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An '''oxoacid''' is an [[acid]] which contains [[oxygen]]. More specifically, it is an acid which:
#contains oxygen;
#contains at least one other [[Chemical element|element]];
#has at least one [[hydrogen]] atom bound to oxygen; and
#forms an ion by the loss of one or more protons.{{ref|Boric}}
The name '''oxyacid''' is sometimes used, although this is not recommended.
Generally, oxoacids are simply [[polyatomic ions]] with a hydrogen [[cation]].
Under [[Lavoisier]]'s original [[Acid-base reaction theories|theory]], all acids contained oxygen, which was named from the [[Greek language|Greek]] οξυς (''oxys'') (acid, sharp) and γεινομαι (''geinomai'') (engender). It was later discovered that some acids, notably [[hydrochloric acid]], did not contain oxygen and so a distinction was made for those that did.
Common oxoacids include:
*Halogen oxoacids: [[Hypochlorous acid]]; [[Chlorous acid]]; [[Chloric acid]]; [[Perchloric acid]]; [[Perbromic acid]]; [[Metaperiodic acid]]
*[[Sulfuric acid]]
*[[Nitric acid]]
*[[Phosphoric acid]]
Common acids which are not oxoacids include:
*[[Hydrochloric acid]]
*[[Hydrofluoric acid]]
*[[Hydrobromic acid]]
*[[Hydroiodic acid]]
Although [[carboxylic acid]]s fulfill the criteria above, they are not generally considered as oxoacids.
All oxoacids have the acidic hydrogen bound to an oxygen atom, so bond strength (length) is not a factor as it is with binary nonmetal hydrides. Rather, the electronegativity of the central atom (E) and the number of O atoms determine oxoacid acidity. With the same central atom E, acid strength increases as the number of oxygen attached to E increases. With the same number of oxygens around E, acid strength increases with the electronegativity of E.
== Note ==
#{{note|Boric}} This final criterion has the effect of excluding [[boric acid]] from the strict definition, as it forms its anion by addition of hydroxide rather than loss of a proton: B(OH)<sub>3</sub> + H<sub>2</sub>O {{unicode|⇌}} [B(OH)<sub>4</sub>]<sup>−</sup> + H<sup>+</sup>. However, boric acid is usually considered to be an oxoacid nonetheless.
==See also==
*[[Strong Acid]]
*[[Weak Acid]]
*[[Electronegativity]]
==External links==
*[http://www.iupac.org/goldbook/O04374.pdf IUPAC definition of "oxoacid"] (from the "''Gold Book''")
[[Category:Acids]]
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[[es:Ácido oxácido]]
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[[ko:산소산]]
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[[ja:オキソ酸]]
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[[zh:含氧酸]]