Estimation of phosphorous:
Second method: A known mass of compound is heated with fuming `HNO_(3)` or sodium peroxide `(Na_(2)O_(2)` in Carius tube which converts phosphorous to `H_(3)PO_(4)`. Magnesia mixture `(MgCl_(2)+NH_(4)Cl)` is then added, which gives the percipate of magnesium ammonium phosphate `(MgNH_(4).PO_(4))` which on heating gives magnesium pyrophosphate `(Mg_(2)P_(2)O_(7))` , which is weighted.
Percentage of P`=("Atomic mass of P")/("Molecular mass of " Mg_(2)P_(2)O_(7)) xx ("Molecular mass of "Mg_(2)P_(2)O_(7) xx 100)/("Mass of compound")=(62)/(222) xx("Mass of " Mg_(2)P_(2)O_(7)xx 100)/("Mass of compound")`
An organic compound has 6.2% of phosphorus .In the reaction sequence , all phosphorous is converted to `Mg_(2)P_(2)O_(7)` . Find wt. of `Mg_(2)P_(2)O_(7)` formed
A. 2.22
B. 10.2
C. 15
D. 20
