# Why does KMnO4 oxidize iodide to iodine in acidic medium, whereas iodide to iodate in alkaline medium?

$\ce{KMnO4}$ should be a better oxidizing agent in acidic medium, than in alkaline medium, as per my knowledge. However, it oxidizes iodide (oxidation state = -1) to iodine (0) in acidic medium, whereas iodide (-1) to iodate (+5) in alkaline medium. The latter has a higher change in oxidation number, which we would have instead expected for the former. Why is this so?

• My book (NCERT India) mentions the same oxidation (iodide to iodate) for even neutral/faintly alkaline medium ($\ce{2MnO4- + H2O + I2 -> 2MnO2 + 2OH- + IO3-}$), which should be even weaker than the alkaline $\ce{KMnO4}$. It'd be interesting if an answer elaborated upon this as well. – Gaurang Tandon May 7 '18 at 5:17