Monopotassium arsenate
# Monopotassium arsenate

Monopotassium arsenate is the inorganic compound with the formula $KH_2AsO_4.$ 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:

    $H_3AsO_4$ + $H_2O$ ⇌ H $_2AsO^−$ $_4$ + $H_3O^+$ $(pK_{a1}$ = 2.19)
    H $_2AsO^−$ $_4$ + $H_2O$ ⇌ $HAsO^{2−}$ $_4$ + $H_3O^+$ $(pK_{a2}$ = 6.94)

## Related compounds

* Trisodium arsenate, $Na_3AsO_4$
* Disodium hydrogen arsenate, $Na_2HAsO_4$
