Test: Purification of Organic Compounds - JEE MCQ

Fractional distillation

Kjeldahl′s method depends upon the fact that most of the organic compounds containing nitrogen are quantitatively decomposed to give (NH₄)₂SO₄ when heated strongly with conc. H₂SO₄. In this method CuSO₄ acts as catalytic agent.

To convert covalent compounds into ionic compounds such as NaCN,Na₂ S,NaX, etc.

Carboxylic acids dissolve in sodium bicarbonate, while phenol does not.

In Dumes method,
% of nitrogen

Na₂S and NaCN, formed during fusion with metallic sodium, must be removed before adding AgNO₃, otherwise black ppt. due to Na₂S or white precipitate due to AgCN will be formed and thus white precipitate of AgCl will not be identified easily.

Beilstein test – In this test organic compound is heated on a copper wire in a flame. The appearance of a green or bluish green flame due to the formation of volatile cupric halides indicate the presence of halogens in the organic compound. (It does not tell which halogen is actually present).

Percentage of

NaOH is base so it will react with acid.
H which is attached with -COOH is more acidic due to the stability of conjugate base (equivalent resonating structure). So, b and c is more basic. And in a and b, b is more acidic because it's conjugate base is stabilised due to -I effect of -NO₂

The double bond equivalent (DBE) value of the given compound is 11

Reaction takes place in Lassaigne's test are as:



So, is responsible for prussian blue colour obtained during the test of Nitrogen and Lassaigne test. O-nitrophenal is more volatile than pnitrophenal. There is intramolecular H - bonding in O- nitrophenal while in P- nitrophenal there is intermolecular hydrogen bonding which cause association of molecule. Intermolecular H - bondingincrease, boiling point increases while volatility reduces.

sublimation

fractional crystallization

The distillate collected is the liquid of lower boiling point

distillation under reduce pressure

steam distillation

nan

adsorption