Question

I. Ethanol
II. Acetic acid
III. Phenol
IV. Acetonitrile
The acidity of compounds I-IV in water follows the order:

• A. $IV<I<III<II$
• B. $IV<III<I<II$
• C. $I<II<III<IV$
• D. $IV<I<II<III$

Answer 1

Answer: (A)

Acetic acid is stronger acid than phenol because negative charge is declocalised on two oxygen atom centers in acetic acid while charge in phenol is delocalised on one oxygen atom and three carbon centers.

Phenol is strong acid than ethanol because phenoxide ion is more stable than ethoxide ion.

Acetonitrile is less acidic than acids and alochols due to less stable conjugate base left after removal of proton.