Q59 / 180 · JIPMER 2017 · Chemistry

When $\mathrm{I}^{-}$is oxidised by $\mathrm{MnO}_4^{-}$in alkaline medium, $\mathrm{I}^{-}$converts into

  • Correct answer
    A
    $\mathrm{IO}_3^{-}$
  • B
    $I_2$
  • C
    $\mathrm{IO}_4^{-}$
  • D
    $I0^{-}$

Solution

When $\mathrm{I}^{-}$is oxidised by $\mathrm{MnO}_4^{-}$in alkaline medium, $\mathrm{I}^{-}$converts into $\mathrm{IO}_3^{-}$. The reaction occurs as follows. $\begin{gathered}2 \mathrm{KMnO}_4+2 \mathrm{KOH} \longrightarrow \mathrm{K}_2 \mathrm{MnO}_4+\mathrm{H}_2 \mathrm{O}+[\mathrm{O}] \\ \xrightarrow[2]{\mathrm{K}_2 \mathrm{MnO}_4+2 \mathrm{H}_2 \mathrm{O} \longrightarrow 2 \mathrm{MnO}_2+4 \mathrm{KOH}+2[\mathrm{O}]} \\ 2 \mathrm{KMO}_4+\mathrm{H}_2 \mathrm{O} \xrightarrow{\text { Alkaline }} 2 \mathrm{MnO}_2+2 \mathrm{KOH}+3[O]\end{gathered}$ $\mathrm{KI}+3[\mathrm{O}] \longrightarrow \mathrm{KIO}_3$ i.e. $\mathrm{IO}_3^{-}$-ion

Hence, the correct answer is option: 'A'.

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