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How to Balance Redox Reactions - Balancing Redox Reactions

By Anne Marie Helmenstine, Ph.D., About.com

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Balancing Redox Reactions - Balance the Charge

Next, balance the charges in each half-reaction so that the reduction half-reaction consumes the same number of electrons as the oxidation half-reaction supplies. This is accomplished by adding electrons to the reactions:

2 I- → I2 + 2e-

5 e- + 8 H+ + MnO4- → Mn2+ + 4 H2O

Now multiple the oxidations numbers so that the two half-reactions will have the same number of electrons and can cancel each other out:

5(2I- → I2 +2e-)

2(5e- + 8H+ + MnO4- → Mn2+ + 4H2O)

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