alleryStart learning →Manganese moves from the 7+ state in permanganate to the 2+ state. How many electrons does each manganese center gain?
ATwo electrons
BSeven electrons
CFive electrons
DNine electrons
Answer & Solution
Correct answer: C. Five electrons
1. Each electron gained lowers the oxidation state by one unit.
2. The starting state is 7+ and the finishing state is 2+.
3. The drop is 7 minus 2, which is 5 units.
4. Five units of drop means five electrons gained per manganese center.
5. That is why the balanced half-reaction carries 5 electrons on the reactant side.
6. Answering two electrons reads off the final charge instead of the change.
7. Answering seven electrons reads off the starting charge instead of the change.
8. Answering nine electrons adds the two states rather than subtracting them.
_Source: OpenStax Chemistry (CC BY 4.0), Chs 7 and 17, section 17.1 Balancing Oxidation-Reduction Reactions_
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