AskDefine | Define oxyacid

Dictionary Definition

oxyacid n : any acid that contains oxygen [syn: oxygen acid]

User Contributed Dictionary



  1. An acid containing oxygen, as opposed to a hydracid.



Extensive Definition

An oxoacid is an acid which contains oxygen. More specifically, it is an acid which:
  1. contains oxygen;
  2. contains at least one other element;
  3. has at least one hydrogen atom bound to oxygen; and
  4. 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 theory, all acids contained oxygen, which was named from the 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 acids which are not oxoacids include:
Although carboxylic acids 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.


  1. 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)3 + H2O  [B(OH)4]− + H+. However, boric acid is usually considered to be an oxoacid nonetheless.

External links

oxyacid in Estonian: Hapnikhapped
oxyacid in Spanish: Ácido oxácido
oxyacid in French: Oxoacide
oxyacid in Korean: 산소산
oxyacid in Italian: Ossiacidi
oxyacid in Japanese: オキソ酸
oxyacid in Portuguese: Oxiácido
oxyacid in Chinese: 含氧酸
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