Question

${\left({\mathrm{NH}}_4\right)}_2{\mathrm{MoO}}_4$ is used for the detection of_________

Answer 1

Detection of Phosphorus:-

1. ${\left({\mathrm{NH}}_4\right)}_2{\mathrm{MoO}}_4$(Ammonium orthomolybdate) is actually a white solid which is prepared by the treatment of Molybdenum trioxide with the aqueous ammonia.
2. The organic compound Ammonium orthomolybdate would be treated with the sodium peroxide $\left({\mathrm{Na}}_2{\mathrm{O}}_2\right)$, and Phosphorus will get converted to the Sodium Phosphate.
3. The aqueous extract is further heated with the concentrated Nitric acid $\left({\mathrm{HNO}}_3\right)$ as well as the Ammonium molybdate .
4. A canary yellow precipitate of the Ammonium phosphomolybdate is then further collected.
5. This yellow precipitate which is formed will show the presence of Phosphorus in the organic compound.
6. Reactions involved in this process:-

$\underset{\mathrm{Trisodium}\mathrm{phosphate}}{{\mathrm{Na}}_3{\mathrm{PO}}_{4\left(\mathrm{aq}\right)}}+\underset{\mathrm{Nitric}\mathrm{acid}}{3{\mathrm{HNO}}_{3\left(\mathrm{aq}\right)}}⟶\underset{\mathrm{Phosphoric}\mathrm{acid}}{{\mathrm{H}}_3{\mathrm{PO}}_{4\left(\mathrm{aq}\right)}}+\underset{\mathrm{Sodium}\mathrm{nitrate}}{3{\mathrm{NaNO}}_{3\left(\mathrm{aq}\right)}}$

$\underset{\mathrm{Phosphoric}\mathrm{acid}}{{\mathrm{H}}_3{\mathrm{PO}}_{4\left(\mathrm{aq}\right)}}+\underset{\mathrm{Ammonium}\mathrm{orthomolybdate}}{12{\left(\mathrm{NH}4\right)}_2{\mathrm{MoO}}_{4\left(\mathrm{aq}\right)}}+\underset{\mathrm{Nitric}\mathrm{acid}}{21{\mathrm{HNO}}_{3\left(\mathrm{aq}\right)}}⟶\underset{\mathrm{Ammonium}\mathrm{phosphomolybdate}}{{\left(\mathrm{NH}4\right)}_3{\mathrm{PO}}_4\cdot 12{\mathrm{MoO}}_{3\left(\mathrm{s}\right)}}\downarrow +\underset{\mathrm{Ammonium}\mathrm{nitrate}}{21{\mathrm{NH}}_4{\mathrm{NO}}_{3\left(\mathrm{aq}\right)}}+\underset{\mathrm{Nitrous}\mathrm{oxide}}{12{\mathrm{N}}_2{\mathrm{O}}_{\left(\mathrm{g}\right)}}$

Therefore, ${\left({\mathrm{NH}}_4\right)}_2{\mathrm{MoO}}_4$ is used for the detection of Phosphorus.