How to Balance Redox Reactions (Basic Solution)
You've seen how to balance a redox reaction in an acidic solution. It involves adding H+ to one side of the equation. What if you're in basic solution? It's the same process, but there's one additional step. Try balancing this redox reaction, in basic solution:
The oxidation number of C changes from -2 to +4 (an increase of 6)
The oxidation number of Mn changes from +7 to +6 (a decrease of 1)
The lowest common multiple between these two is 6.
One C atom loses 6 electrons.
Six Mn atoms lose 1 electron each.
The oxidation number of Mn changes from +7 to +6 (a decrease of 1)
The lowest common multiple between these two is 6.
One C atom loses 6 electrons.
Six Mn atoms lose 1 electron each.
Add H2O to whichever side lacks oxygen, and add H+ to account for the H atoms we just added (and the H atoms that were present before!)
Since this reaction is occurring in basic solution, we need to convert the H+ into OH-. We do this by adding OH- to both sides of the equation. Then, the OH- and H+ ions from one side will cancel each other out, to make H2O!
See how that worked? Pretty slick, eh!