Question

What is the final Product during the estimation of Phosphorous by Carius Method ?

• A. $M{g}_2{P}_2{O}_7$
• B. $M{g}_2{P}_2{O}_5$
• C. $MgN{H}_{4}P{O}_4$
• D. $MgN{H}_{2}P{O}_4$

Answer 1

The correct option is A $M{g}_2{P}_2{O}_7$

A known mass (0.2 - 0.3 g) of the organic substance is heated with fuming nitric acid in a Carius tube for about 2 hours. The phosphorus of the organic compound gets converted into phosphoric acid. The total phosphate content of the solution is reacted with magnesia mixture (mixture of a solution containing magnesium chloride, ammonium chloride and a little ammonia) to precipitate it as $MgN{H}_{4}P{O}_4.$ The precipitate of $MgN{H}_{4}P{O}_4$ is filtered, washed, dried and then ignited to give magnesium pyrophosphate $\left(M{g}_2{P}_2{O}_7\right).$