1. Tardigrade
  2. Question
  3. Chemistry
  4. 0.5 gm of an organic substance containing phosphorous was heated with conc. HNO 3 in the Carius tube. The phosphoric acid thus formed was precipitated with magnesia mixture( .MgNH 4 PO 4) which on ignition gave a residue of 1.0 gm of magnesium pyrophosphate ( Mg 2 P 2 O 7). The percentage of phosphorous in the organic compound is:

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. $0.5 \,gm$ of an organic substance containing phosphorous was heated with conc. $HNO _3$ in the Carius tube. The phosphoric acid thus formed was precipitated with magnesia mixture( $\left.MgNH _4 PO _4\right)$ which on ignition gave a residue of $1.0$ gm of magnesium pyrophosphate $\left( Mg _2 P _2 O _7\right)$. The percentage of phosphorous in the organic compound is:

Organic Chemistry – Some Basic Principles and Techniques

Solution:

image
Mw of $Mg _2 P _2 O _7=24 \times 2+31 \times 2+16 \times 7=222$
Percentage of $P =\frac{62}{222} \times \frac{\text { Weight of } Mg _2 P _2 O _7}{\text { Weight of compound }} \times 100$
$=\frac{62}{222}=\frac{1.0}{0.5} \times 100=55.85 \%$