Question

1.explain with reasons : pKb of aniline is more than that of methylamine. 2. give reasons : Sulphanilic acids is insoluble in water but is soluble both in aqueous bases &aqueous mineral acids taken seperately.

Answer 1

 In aniline, the lone pair of electrons on the N atom is delocalised over the benzene ring which results in the decrease in electron density. While in CH3NH2, the +I effect of CH3 increases the electron density on the N atom. So aniline is a weaker base than methylamine

 Being more basic than water, methylamine accepts a proton from water-liberating OH− ions.These OH− ions combine with Fe3+ ions present in H2O to form a brown precipitate of hydrated ferric oxide.