Phosphorous acid, min. 98 %, cryst., Molar mass (M) 82,0 g/mol, Density (D) 1,65 g/cm³, Boiling point (bp) 259 °C, CAS No. [13598-36-2], UN-Nr. 2834, EG-Nr. 237-066-7, Empirical formula H3PO3