GIVE a chemical test to distinguish between formic acid and acetic acid

HCOOH REACTS WITH TOLLENS REAGENT [ AMMONICAL SILVER NITRATE] ,SILVER MIRROR IS FORMED WHILE CH₃COOH DOES NOT REACTS WITH TOLLENS REAGENT.

Test 1: To distinguish between formic acid and acetic acid use tollens(tollens reagent = ammonical silver nitrate solution) test(silver mirror) or fehling solution . Formic acid gives positive indicated by the formation of a silver mirror( Silver oxide precipitate on the walls of the test tube) test but acetic acid fails to form a silver mirror. This is because the formic acid behaves as an aldehyde as there is a CHO group the other side of the OH group and it is easily oxidised to CO2. Test 2: Take 3 drops of both the formic acid and acetic acid in 2 different test tubes, add 1 ml of distilled water, & 1-2 drops of dilute KMnO4 solution - the formic acid instantly decolorises pink color of KMnO4, while acetic acid does not. Regards, Sakthi Ganesh IIT JEE Aspirant (IIT JEE 2014)

Dear Student

1. By using tollens test (Silver Mirror Test) or fehling solution .

2. By using Acidified KMnO₄.

I hope this answer will help you.
Thanks & Regards
Yash Chourasiya