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Aldehydes, Ketones and Carboxylic Acid — Chemistry STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 ScienceChemistryAldehydes, Ketones and Carboxylic Acid4 Marks
Question
Write the test by which following are distinguished:
(i) Ethanol and Acetaldehyde
(ii) Phenol and carboxylic acid
(iii) Aldehyde and Ketone
(iv) Formic and Acetic acid
✓

Answer

(i) Ethanol and Acetaldehyde : On adding ethanoic acid to ethanol, a fruity smell is evolved which is due to formation of ester. On adding ethanoic acid to acetaldelyde, no such fruity smell is observed.
(ii) Phenol and Carboxylic Acid : They can be easily distinguished by sodium bicarbonate test. It reacts with carboxylic acid but not with phenol.
(iii) Aldehyde and Ketone : Tollen's test also konwn as silver mirror test is used to distinguish aldehyde and ketone. Tollen's reagent oxidizes an aldehyde into the corresponding carboxylic acid whereas ketones are not oxidized.
(iv) Formic Acid and Acetic Acid : Formic and gives test to Tollen's reagent by forming a silver mirror but acetic acid fails to do so.

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