Ammonium phosphate and lead nitrate react to form lead phosphate and ammonium nitrate. The reaction can be represented by the following equation:

(NH4)3PO4 + 3Pb(NO3)2 → Pb3(PO4)2 + 3NH4NO3

Lead phosphate is a white, crystalline solid that is insoluble in water. Ammonium nitrate is a white, crystalline solid that is soluble in water.