Rank the following conjugate bases in order of decreasing basicity, putting the most basic first.

Question

Quizplus · Accepted Answer

Basicity of a conjugate base depends on the stability of the conjugate acid. The more stable the conjugate acid, the less basic the conjugate base. In this case, III has the most stable conjugate acid because the negative charge is delocalized across the entire molecule. Therefore, III is the least basic. Between I and II, II has the more stable conjugate acid because the negative charge is spread over two electronegative oxygen atoms, while I has the negative charge concentrated on one oxygen atom. Therefore, II is less basic. So, the order of decreasing basicity is III > I > II, which is given in choice C.

Rank the Following Conjugate Bases in Order of Decreasing Basicity