Saturday, February 9, 2008

Ch.34 Practical Organic Chemistry - Carboxylic Acids

Distinguishing various compounds

1. Forming acid and acetic acid

i) Silver mirror test with Tollen's reagent: Formic acid gives this test and silver precipitate is formed when Tollen's reagent is added to formic acid.

Formic acid -- HCOOH
Tollen's reagent -- [Ag(NH3)2]OH

Acetic acid does not give this test.

ii) Reaction with mercuric chloride solution: Formic acid in reaction with mercuric chloride solution gives white precipitate.

Mercuric chloride--HgCl2

2. Acetic acid and acetone

Acetic acid CH3COOH
Acetone CH3COCH3

i) Reaction with sodium bicarbonate (NaHCO3): Acetic acid reacts with NaHCO3 to give effervescence as CO2 is evolved.

Acetone has no such reaction.

ii) Iodoform: Acetone reacts with alkaline solution of iodine to give yellow precipitate due to the formation of iodoform (CHI3).

Acetic acid does not give this test.

3. Ethanol and acetic acid

Ethanol C2H5OH
Ehtanol is an alcohol and acetic acid is a carboxylic acid

Carboxylic acid turns blue litmus red. Alcohol has no effect on litmus.
Alcohol has no reaction with sodium bicarbonate. Carboxylic acids give effervescence due to evolution of CO2.

Hence acetic acid gives effervescence with NaHCO3. Ethanol does not give.

Do the spot exercise - go to
http://iit-jee-chemistry-ps.blogspot.com/2008/02/ch34-poc-carboxylic-acids-spot-exercise.html

1 comment:

Paul Jose said...

Does acetic acid react with nahco3