Question

among 2 nitrophenol and 3 nitrophenol which is more stable and which is more acidic?

Answer 1

o-nitrophenol i.e 2- nitrophenol is more stable and acidic than m-nitrophenol i.e 3-nirtophenol due to resonance.
based on looking at resonance structures one can easily see that the meta version will be incapable of delocalizing the electrons onto the nitro group, which means on the O atom of the group. O loves electrons! but in para and Ortho versions, this happens to the same extent; the O atom in the nitro group can have the electrons from broken O-H bond. The electrons are delocalized to a similar extent. so this brings us to dipole moment and distance between opposite charges. The N atom of nitro group will always be positive. The nitro groups are farthest from carbonyl and from negative charged carbons of benzene ring as the electrons are delocalized around it. The para should be most acidic due to higher stability based on charge saperation. The dipole is greater for the para version, which means the initial pull of electron density from the O-H bond is greater than ortho version. Which clearly means that m(2) <o(3)<p(1).
hope it helps