Explain why is ortho-nitrophenol more acidic than ortho-methoxyphenol ?

Explanation

Due to strong-R and -I-effect of the `NO_(2)` group, electron density of the O-H bond decreases and hence the loss of a proton becomes easy.

Further, after the loss of a proton, the o-nitrophenoxide ion left behind is stabilized by resonance and electron withdrawing - `NO_(2)` group which withdraws electrons and disperes the negative charge.

In contrast, due to + R effect of the `-OCH_(3)` group, it increases the electron dencity of the O-H bond therefore making the loss of proton difficult.

Further more, the o-methoxyphenoxide ion left after the loss of a proton is destabilized by resonance. The two negative charge repel each other thereby destabilizing the o-methoxy phenoxide ion.

Further the presence of electron donating `-OCH_(3)` group intensifies the negative charge thereby destabilising the phenoxide ion. Thus, o-nitrophenol is more acidic than o-methoxyphenol.