Phosphorous acid
CAS 13598-36-2
EC 237-066-7
Formula H3O3P
MW 82 g/mol
Inorganic Acids Water TreatmentTextile, Leather & PaperAgriculture & FeedMining & Metals pH Regulation & BufferingChelation & SequestrationCorrosion Inhibition
Description
Phosphorous acid (CAS 13598-36-2, H3PO3) is an inorganic acid also known as phosphonic acid, orthophosphorous acid, or H3PO3. It carries no E-code designation and is distinct from phosphoric acid in both structure and reactivity. It is supplied as a white crystalline solid with EC number 237-066-7.
In water treatment, H3PO3 functions as a scale inhibitor and corrosion suppressant by chelating metal ions that would otherwise form deposits on pipe surfaces. In agriculture, it serves as a phosphonate-based nutrient source and acts as a reducing agent in formulations targeting fungal pathogens. Textile and leather processors use it for pH buffering during dyeing and tanning operations.
This product is available in technical and industrial grades, supplied in compliance with REACH regulations. Standard packaging includes 25 kg bags and bulk quantities for industrial procurement. Buyers should confirm grade specifications against application requirements, particularly where agricultural or water treatment approvals apply.
In water treatment, H3PO3 functions as a scale inhibitor and corrosion suppressant by chelating metal ions that would otherwise form deposits on pipe surfaces. In agriculture, it serves as a phosphonate-based nutrient source and acts as a reducing agent in formulations targeting fungal pathogens. Textile and leather processors use it for pH buffering during dyeing and tanning operations.
This product is available in technical and industrial grades, supplied in compliance with REACH regulations. Standard packaging includes 25 kg bags and bulk quantities for industrial procurement. Buyers should confirm grade specifications against application requirements, particularly where agricultural or water treatment approvals apply.
Physical Properties
| Melting Point | ~73 °C (approx) |
| Boiling Point | 200 °C |
| Density | 1.651 g/mL at 25 °C(lit.) |
| Flash Point | 200°C |
| Appearance | white crystalline solid |
| Color | White |
| Form | Crystals |
| Water Solubility | SOLUBLE |
| Vapor Pressure | 0.001Pa at 20℃ |
| pH | pKa1= 1.10, pKa2 = 6.33(25℃) |
Safety & Handling (Learn More)
Danger GHS05 GHS07
H
H290H302H314H318H335
P
P234P260P261P264P270P271P280P316P317P319P321P330P363P390P405P406P501P264+P265P301+P317P304+P340P403+P233P301+P330+P331P302+P361+P354P305+P354+P338
Trade & Regulatory
| HS Code | 28092019 |
| UN Number | 2834 |
| ADR Class | 8 |
| Packing Group | III |
| Storage Class | 8A - Combustible corrosive hazardous materials |
| WGK (Germany) | 1 |
Other Names
Phosphonic acidH3PO3PHOSPHORUS ACIDorthophosphorusORTHOPHOSPHOROUSO-PHOSPHOROUS ACID
Related Products
Raw Materials
Derivatives
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