In an organic compound phosphorus is estimated as

Options

(a) Mg₂P₂O₇
(b) Mg₃(PO₄)₂
(c) H₃PO₄
(d) P₂O₅

Correct Answer:

Mg₂P₂O₇

Explanation:

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 magnesium mixture i.e MgSO₄ + NH₄Cl + NH₄OH, so that magnesium ammonium phosphate MgNH₄PO₄ is formed which is collected, washed, dried and ignited to get magnesium pyrophosphate Mg₂ P₂O₇, which is then weighed. H₃PO₄ → MgNH₄PO₄ + 3HCl(Magnesium ammonium phosphate (white ppt.). 2MgNH₄PO₄ → Mg₂P₂O₇ ↓ + 2NH₃ + H₂O. Knowing the weight of Mg₂P₂O₇, percentage of phosphorus can be calculated.