In an organic compound, phosphorus is estimated as

A pre-weighed amount of organic compound is heated with concentrated nitric acid (HNO3) in a tube. Phosphorus present in the compound gets converted into phosphoric acid. Now the content of tube are heated with magnesia mixture MgSO4+NH4Cl+NH4OH, so that magnesium ammonium phosphate MgNH4PO4 is formed which is collected, washed, dried and ignited to get magnesium pyrophosphate Mg2P2O7, which is then weighed.H3PO4Phosphoricacid →Magnesia mixtureMgNH4PO4+3HClMgnesium ammoniumphosphate (white ppt.) 2MgNH4PO4⟶ΔMg2P2O7↓+2NH3+H2OKnowing the weight of Mg2P2O7, percentage of phosphorus can be calculated.