Oxoacids

Oxoacids are ternary compounds formed by hydrogen, oxygen, and a third element (typically a nonmetal or a transition metal). The general formula is H_aX_bO_c, where X is the central atom.

Traditional (common) nomenclature

Traditional names are based on the oxidation state of the central atom. Use -ous for the lower oxidation state and -ic for the higher one. When more than two oxidation states exist, the prefixes hypo- and per- are used to indicate the extremes.

Pattern: "acid" + (prefix if any) + root of the central element + suffix

• hypo- ... -ous: lowest oxidation state
• -ous: lower oxidation state
• -ic: higher oxidation state
• per- ... -ic: highest oxidation state

Examples for chlorine oxoacids:

• HClO: hypochlorous acid (Cl oxidation state: +1)
• HClO₂: chlorous acid (Cl oxidation state: +3)
• HClO₃: chloric acid (Cl oxidation state: +5)
• HClO₄: perchloric acid (Cl oxidation state: +7)

Prefix-based (additive) nomenclature

This systematic naming specifies the number of hydrogen and oxygen atoms using multiplicative prefixes, for example dihydrogen(tetraoxophosphate) or hydrogen(trioxonitrate).

Common oxoacids

• H₂CO₃: carbonic acid — responsible for acidity in carbonated beverages.
• H₂SO₃: sulfurous acid — used as a preservative in some contexts.
• HNO₃: nitric acid — used in fertilizer manufacture, explosives, and dyes.
• H₃PO₄: phosphoric acid — used in the food industry and fertilizers.
• H₃BO₃: boric acid — antiseptic and preservative applications.