Phosphonic Acid (CAS 13598-36-2), also known as phosphorous acid, is a diprotic inorganic acid supplied as a white crystalline solid or syrupy liquid with strong reducing and chelating properties, used primarily as a stabilizer and corrosion inhibitor in water treatment and as an intermediate for phosphonate derivatives.
Typical Properties
| Molecular formula | H3O3P |
|---|---|
| Molecular weight | 82 g/mol |
| Appearance | white crystalline solid |
| Form | Crystals |
| Color | White |
| Melting point | ~73 °C (approx) |
| Boiling point | 200 °C |
| Density | 1.651 g/mL at 25 °C |
| Water solubility | SOLUBLE |
| Flash point | 200°C |
| pH | pKa1= 1.10, pKa2 = 6.33(25°C) |
| GHS signal word | Danger · Corrosive, Irritant / harmful |
| HS code | 28092019 |
Typical literature values for identification; lot-specific results are stated on the certificate of analysis (COA) and the safety data sheet (SDS) that accompany every delivery.
Phosphonic Acid
Applications
Used in water treatment, scale prevention, and metal surface conditioning. It also acts as a reducing agent in chemical synthesis and as an intermediate for phosphonate derivatives.
Safety & Risks
Corrosive; may cause burns upon contact. Avoid heating above decomposition point to prevent phosphine gas release.
Packaging
Delivered in 25 kg bags (solid) or 200 kg drums (liquid). Store sealed, dry, and in corrosion-resistant containers.