Write the reaction equations H3PO4 → K3PO4 → Ag3PO4

In order to carry out the above chain of transformations, we need to carry out two reactions.

The first reaction of interaction of concentrated phosphoric acid and concentrated potassium hydroxide solution. As a result of the reaction, the potassium phosphate salt is formed and water is released. The reaction proceeds as a substitution. The chemical equation for the reaction is as follows:

H3PO4 + 3 KOH = K3PO4 + 3 H2O.
The second reaction is the interaction of potassium phosphate and silver nitrate, as a result of the reaction, a silver phosphate salt is formed, which precipitates from an insoluble precipitate and a potassium nitrate salt. The reaction proceeds as a substitution. The chemical equation for the reaction is as follows:

K3PO4 + 3 AgNO3 = Ag3PO4 + 3 KNO3.