Addition of nitric acid, HNO3, and ammonium molybdate, (NH4)2MoO4, to a solution containing aqueous sodium phosphate, Na3PO4, results in the formation of a yellow precipitate of ammonium called 12-phosphomolybdate, (NH4)3PMo12O40 and two aqueous nitrate solutions: ammonium nitrate, NH4NO3 and sodium nitrate, NaNO3. Water is also formed in this reaction. Note that 12-phosphomolybdate is a very big anion! If needed, heating in a boiling water bath can increase the rate of this reaction. You will use the formation of a yellow solid on addition of HNO3 and (NH4)2MoO4 to a sample to indicate that the phosphate ion, PO43-, is present.