Question

Arrange the following in the decreasing order of acidity.
Also give reason:
p-nitrophenol, o-nitrophenol and m-nitrophenol

Answer 1

The decreasing order of acidity is
p-nitrophenol > o-nitrophenol > m-nitrophenol > phenol.
Nitrophenol is more acidic than phenol. Nitro group is electron withdrawing group. It stabilizes the phenoixde ion by dispersing negative charge and facilitates the release of $H^{+}$ ions from phenol. This acid strengthening effect is more when a substitutnt is present in o- or p- position than in m- position to the phenolic group.