Give the test for detection of P in an organic compound.

Explanation

Lead acetate test : A part of Lassaigne.s extract is acidified with dilute acetic acid. Then lead acetate is added to it. Appearance of black precipitates indicate the presence of sulphur in the given organic compound.
`Na_2S +(CH_2COO)_2Pb to underset("(Black ppt.)")(PbS + 2CH_3COONa)`
iii) Detection of phosphorus : For the detection of phosphorus, the given organic compound is fused with sodium peroxide to form sodium phosphate.
`underset("(Sodium peroxide)")(5Na_2O_2) + 2P overset(Delta)(rarr) underset(2Na_3PO_4) + 2Na_2O`
Ammonium molybdate test: The solution formed is boiled with conc. `HNO_3`. Then ammonium molybdate is added to it. Appearance of yellow colour precipitate indicates the presence of phosphorus in the compound.
`Na_3PO_4 + 3HNO_3 overset(Delta)(rarr)H_3PO_4 + 3NaNO_3`
`H_3PO_4 + underset("Amm. Molybdate")(12(NH_4)_2)+21HNO_3 to underset("(yellow ppt.)")underset("Amm. phosphomolybdate")((NH_4)_3 PO_4. 12MoO_3 + 21NH_4NO_3 + 12H_2O`