Chlorous acid is an inorganic compound with the formula HClO2. It is a pale-yellow 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):
2 HClO2 → HClO + HClO3
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).