Hypophosphorous acid English name: Hypophosphorous acid Also known as: Hypophosphorus acid Chemical formula: H?PO? Molecular weight: 65.99 CAS Registry Number: 6303-21-5 EINECS number: 228-601-5 Density: 1.439 Appearance: Colorless oily liquid or deliquescent crystals; commercially available as a 50% aqueous solution. Melting point: 26.5°C Boiling point: 130°C Uses: 1. Strong reducing agent, used in the preparation of hypophosphites such as sodium hypophosphite and calcium hypophosphite. 2. Used in electroplating baths, pharmaceuticals, and as a general reagent. 3. Used for the reduction of diazonium salts (de-diazotization) and the reductive removal of halogens from aromatic rings of polynitro compounds.