Complete and balance the following redox reaction in basic solution

Question

MnO₄^-_(aq) +Br^-_{(aq) -->} MnO_2(s) +BrO₃^-_(aq)

Answer 1

MnO4- ===> MnO2

MnO4- ===> MnO2 + 2H2O ... to balance oxygens

MnO4- + 4H+ ===> MnO2 + 2H2O ... to balance hydrogens

MnO4- + 4H+ + 4OH- ===> MnO2 + 2H2O + 4OH- ... because it is in basic solution

MnO4- + 4H2O + 3e- ===> MnO2 + 2H2O + 4OH- ... to balance charge

MnO4- + 2H2O + 3e- ===> MnO2 + 4OH- REDUCTION HALF REACTION

Br- ===> BrO3-

Br- + 3H2O ===> BrO3- ... to balance oxygens

Br- + 3H2O ===> BrO3- + 6H+ ... to balance hydrogens

Br- + 3H2O + 6OH- ===> BrO3- + 6H+ + 6OH- ... because it is in basic solution

Br- + 3H2O + 6OH- ===> BrO3- + 6H2O + 6e- ... to balance charge

Br- + 6OH- ===> BrO3- + 3H2O + 6e- OXIDATION HALF REACTION

Multiply reduction half reaction by 2 to equalize electrons, and add to oxidation half reaction and cancel common items to get the final balanced equation:

2MnO4- + 4H2O + 6e- ===> 2MnO2 + 8OH-

Br- + 6OH- ===> BrO3- + 3H2O + 6e-

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2MnO₄^- + H₂O + Br^- ===> 2MnO₂ + 2OH^- + BrO₃^- ... balanced for mass and charge