What Is Potassium Phosphite?

Potassium phosphite is an alternate name for monopotassium phosphite. It is used commercially as a fertilizer, which is soluble in water and formed by the reaction between phosphorous acid (in an equimolar amount) and a potassium ion, typically from potassium hydroxide or potassium carbonate.

Potassium phosphite has a white-powder crystalline appearance and a molecular formula of H2KO3P, corresponding to two atoms of hydrogen, three of potassium oxide (K2O is the correct formula for potassium oxide) and one of phosphorus. In addition to its solubility in both water and ethanol, the compound is also used to form foliar fertilizer and as a fungicide.