Question

Phenoxide ion has _______ number of resonating structures than benzoate ion and benzoic acid is a _________ acid than phenol.

• A. more, stronger
• B. more, weaker
• C. less, stronger
• D. less, weaker

Answer 1

The correct option is A more, stronger

In the resonating structure of phenoxide, a negative charge is present on C atom (which is less electronegative) while in benzoate ion, a negative charge is present on the more electronegative atoms. Hence, in the ionic structure, if the negative charge is present on more electronegative atoms, it is more stable in comparison to the ion which is having the negative charge on less electronegative atoms. Thus, due to the higher stability of benzoate ion, it is able to provide more $H^{+},$ and as a result, it is more acidic.
$C_6{H}_{5}OH\rightleftharpoons \underset{Lessstable}{C_6{H}_5{O}^{⊝}}+H^{⨁}$
$C_6{H}_{5}COOH\rightleftharpoons \underset{Morestable}{C_6{H}_{5}CO{O}^{⊝}}+H^{⨁}$
So, the order of acidic strength is $C_6{H}_{5}COOH>C_6{H}_{5}OH.$