Question

In Carius method for the quantitative estimation of phosphorous, by using magnesia mixture, phosphorous is estimated by___________.

• A. $MgN{H}_4\cdot P{O}_4$
• B. $M{g}_2{P}_2{O}_7$
• C. $(N{H}_4{)}_{3}P{O}_4\cdot 12Mo{O}_3$
• D. All

Answer 1

Answer: (B)

$M{g}_2{P}_2{O}_7$

The amount of phosphorus present in any organic compound is determined by Carius method.
The phosphorus present in an organic compound is oxidized to phosphoric acid by heating with fuming nitric acid. The phosphoric acid so obtained is precipitated as $MgN{H}_{4}P{O}_4$, which on ignition is converted into $M{g}_2{P}_2{O}_7$. From the mass of $M{g}_2{P}_2{O}_7$, the mass of phosphorus present in the sample of the organic compound can be calculated.