MnO4(aq) + 8H + 5Fe2+ \(\to\) Mn2+(aq) + 5Fe3+(aq) + H2O. The oxidation number of maganese in the above reaction changed from

  • A +7 to +2
  • B +6 to +2
  • C +5 to +2
  • D +4 to +2
jamb 1994chemistry

The correct answer is A. +7 to +2

\(MnO_{{4}{(aq)}}\) has a charge of \(-1\)

Let the oxidation number of \(Mn\) in \(MnO_{{4}{(aq)}}\) be X

Recall, the oxidation number of \(O_{2}\) is \(-2\)

\(\therefore\) \(X + (-2\times 4) = -1\)

\(X - 8 = -1\)

\(X = +7\)

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