One half-reaction releases a single electron and the other consumes five. How must they be scaled before they are added?

1. Electrons released by the oxidation are exactly the electrons taken up by the reduction. 2. So the two half-reactions must show the same number of electrons before they can be added. 3. One half-reaction shows 1 electron and the other shows 5. 4. The lowest common multiple of 1 and 5 is 5. 5. Multiplying the one electron half-reaction by 5 brings it to 5 electrons and leaves the other unchanged. 6. The electrons then cancel when the halves are added, as they must. 7. Multiplying the five electron half-reaction by five would push it to 25 and widen the gap. 8. Multiplying both by five keeps the mismatch at 5 against 25, so nothing cancels. _Source: OpenStax Chemistry (CC BY 4.0), Chs 7 and 17, section 17.1 Balancing Oxidation-Reduction Reactions_