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    Balancing a Reduction-Oxidation Reaction

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    Use the following pair of reduction half-reactions to design a galvanic cell. Then write in the proper coefficient for each of the species involved in the overall reaction. Water molecules and protons are not shown in the half-reactions, but may be needed in the overall reaction.
    MnO4- (aq) --> MnO2 (s) Eo = 0.59 V
    NO3- (aq) --> NO (g) Eo = 0.96 V

    What are the proper coefficients for each of the following:
    NO3- (aq), MnO4- (aq), NO (g), MnO2 (s), H+ (aq), H2O (l)

    © BrainMass Inc. brainmass.com October 9, 2019, 10:45 pm ad1c9bdddf

    Solution Preview

    To start this problem, you need to look at the half-reactions individually:

    1) Balance the half-reactions:

    MnO4- (aq)  MnO2 (s)
    Add 2 H2O molecules to balance the O
    MnO4- (aq)  MnO2 (s) + 2 H2O (l)
    Add 4 H+ ions to balance the H
    MnO4- (aq) + 4 H+ (aq)  MnO2 (s) + 2 H2O (l)
    Balance the charges by adding 3 e-
    MnO4- (aq) + 4 H+ (aq) + 3 e-  MnO2 (s) + 2 H2O ...

    Solution Summary

    This solution explains how to balance a reduction-oxidation reaction by adding H+, electrons, and water so that the combined half-reactions are balanced..