The preparation method of ammonium paratungstate usually involves the mixed reaction of tungstic acid (H2WO4) and ammonia (NH3). The product is a white solid, which can be purified by filtration and drying. The specific reaction equation is as follows:
H2WO4 + 2NH3 + H2O → (NH4)2[WO2(WO3)2] + NH4NO3
