Monopotassium arsenate is the inorganic compound with the formula KH2AsO4. A white solid, this salt is used to prepared other arsenic-containing compounds, mainly pesticides. It is prepared by calcining arsenic oxide and potassium nitrate, followed by extraction with water.
Relevant acid-base equilibria for aqueous solutions of this diprotic acid derived from arsenic acid are as follows:
H3AsO4 + H2O + H3O+ (pKa1 = 2.19)
+ H2O + H3O+ (pKa2 = 6.94)