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(b) Give simple chemical tests to distinguish between the following pairs of compounds : (i) Butanal and Butan-2-one. (iii) Benzoic acid and Phenol. |
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Answer» Solution :(i) BUTANAL and Butan-2-one : `underset("Butanol")(CH_(3)CH_(2)CH_(2)CHO), underset(Butan-2-one)(CH_(3)-overset(O)overset(||)C-CH_(2)-CH_(3))` (1) Butanal on warming with Tollen.s reagent gives silver mirror. This test is not given by butan-2-one (KETONES). (2) Butanal on warming with a mixture containing Fchling A and Fchling B in equal volumes and HEATING gives a reddish brown precipitate. This test is not given by butan-2-one. (ii) Benzoic acid and Phenol : (1) `NaHCO_3` test - To a saturated solution of sodium hydrogen-carbonate, ADD a pinch of the compound. If an effervescence takes place, it is benzoic acid. Phenol does not give this test. (2) Ester test - Heat a little of the compound with ethyl alcohol and a few drops of cone. `H_2SO_4`. A fruity ester smell is given by benzoic acid. Phenol does not give this test. |
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