question_answer 58)

  \[MnO_{4}^{2-}\]undergoes disproportionation reaction in acidic medium but\[MnO_{4}^{2-}\] does not. Give reason.

Answer:

  In\[MnO_{4}^{-}\], manganese is in its highest oxidation state (+7)hence it will not undergo disproportionation. However,\[MnO_{4}^{2-}\] ion will undergo disproportionation in acid medium. \[\overset{(+6)}{\mathop{2MnO_{4}^{2-}}}\,+4{{H}^{+}}\to 2\overset{(+7)}{\mathop{MnO_{4}^{-}}}\,+\overset{(+4)}{\mathop{Mn{{O}_{2}}}}\,+2{{H}_{2}}O\]