oxyacids

An oxyacid is an acid that contains hydrogen, oxygen, and at least one other element, typically a nonmetal. In these compounds, acidic hydrogen atoms are attached to oxygen atoms that are bonded to a central element, and their behavior in water involves donation of protons to form oxoanions.

Oxyacids are commonly described by the general formula HnXOm, where X is the central nonmetal and n and m describe the numbers of hydrogen and oxygen atoms. They are often polyprotic, with multiple acidic protons released stepwise. The acidity of oxoacids often increases with the oxidation state of X and with the number of oxygens; more oxygen and a higher oxidation state stabilize the conjugate base through resonance and inductive effects, yielding stronger acids.

Representative examples include sulfuric acid (H2SO4), nitric acid (HNO3), chloric acid (HClO3), perchloric acid (HClO4), and phosphoric acid (H3PO4). Other oxoacids such as sulfrous acid (H2SO3) and chlorous acid (HClO2) illustrate a decreasing acidity as the number of oxygens drops. In aqueous solutions, these acids dissociate to produce oxoanions like sulfate, nitrate, chlorate, and phosphate, respectively.

Oxyacids play key roles in chemistry and industry, including inorganic synthesis, catalysis, and the manufacture of fertilizers and explosives. Their properties are commonly contrasted with hydracids, which do not contain oxygen, and with organic acids, which may contain other functional groups.