The acidity of EOH varies widely with the nature of element E.
In an important group of acids known as oxoacids, have E is a p-block element (S, P, C or halogen) bonded to oxo groups and hydroxyl groups (OH). As shown below, E bonded to an oxo group can be represented either as E=O or as the polarized form +E-O– (as in HNO3).
The acidity of -OH in oxoacids is higher than that of -OH in water. Their relative acidity depends on the number of oxo- groups at E.
In an important group of acids known as oxoacids, have E is a p-block element (S, P, C or halogen) bonded to oxo groups and hydroxyl groups (OH). As shown below, E bonded to an oxo group can be represented either as E=O or as the polarized form +E-O– (as in HNO3).
The acidity of -OH in oxoacids is higher than that of -OH in water. Their relative acidity depends on the number of oxo- groups at E.
Weak acids have one oxo group.
Strong acids have more than one oxo group.
Strong acids have more than one oxo group.
| weak acids one oxo oxygen at element E (C, S or P) | |||
 |  |  |  |
| CH3CO2H | H2CO3 | H2SO3 | H3PO4 |
| ethanoic acid | carbonic acid | sulfurous acid | phosphoric acid |
| strong acids two or more oxo oxygens at E (N, S or Cl) | ||
 |  |  |
| HNO3 | H2SO4 | HClO4 |
| nitric acid | sulfuric acid | perchloric acid |