Question

Although phenoxide ion has more no. of resonating structures than carboxylate ion , even though carboxylic acid is a stronger acid why ?

Answer 1

The phenoxide ion has non equivalent resonance structures in which –ve charge is at less electronegative C atom and +ve charge as at more electronegative O-atom.

In carboxylate ion –ve charge is delocalized on two electronegative O-atoms hence resonance is more effective and a stronger acid.