Potassium chromate, commonly referred to as tarapacaite, is an inorganic compound at room temperature that is a yellow orthorhombic or hexagonal crystal. It is a conjugate base of chromic acid. The absolute density is 2,732 g/cm3, and 968 ° C is the melting point. It is poisonous and can dissolve into water to form a solution for hydrolysis of alkaline chromate ions.