Answer to Question #225167 in Chemistry for Junior

Question

Balance the following redox reaction in basic media:

CN-

(aq) + MnO4

-

(aq) → CNO-

(aq) + MnO2

Answer 1

The given redox reaction is -

CN⁻+MnO⁻₄→CNO⁻+MnO₂

Oxidation half-reaction:

CN⁻+H₂O+2OH⁻→CNO⁻+2H₂O+2e⁻

Reduction half-reaction:

MnO⁻₄+4H₂O+3e⁻→MnO₂+2H₂O+4OH⁻

Multiply oxidation half-reaction by (3) and reduction half-reaction by (2), to make electron gain equivalent to electron lost,

Oxidation half-reaction:

3CN⁻+3H₂O+6OH⁻→3CNO⁻+6H₂O+6e⁻

Reduction half reaction:

2MnO⁻₄+8H₂O+6e⁻→2MnO₂+4H₂O+8OH⁻

Add both the half-reactions together and simplify the reaction to get the balanced redox reaction

3CN⁻+2MnO⁻₄+H₂O→3CNO⁻+2MnO₂+2OH⁻