Chlorous acid. Molecular model of the inorganic compound, weak acid and powerful oxidizing agent chlorous acid (HClO2). Chlorine here is in its +3 oxidation state, though the molecule is unstable, disproportionating (reducing and oxidising) to hypochlorous acid (+1 oxidation state) and chloric acid (+5 oxidation state). Atoms are represented as spheres and are colour-coded: hydrogen (white), oxygen (red) and chlorine (green).