What is "chlorous acid"

n. (context chemistry English) an unstable acid, HClO₂, known only in solution or as its salts, the chlorites; it is a strong oxidizing agent

n. (HClO2) a strongly oxidizing acid; known only in solution

Chlorous acid is an inorganic compound with the formula HClO. It is a weak acid. Chlorine has oxidation state +3 in this acid. The pure substance is unstable, disproportionating to hypochlorous acid (Cl oxidation state +1) and chloric acid (Cl oxidation state +5):

Although the acid is difficult to obtain in pure substance, the conjugate base, chlorite, derived from this acid is stable. One example of a salt of this anion is the well-known sodium chlorite. This and related salts are sometimes used in the production of chlorine dioxide.