How do you define oxidation and reduction?
Well, you could have two variations that I can think of, and each variation can have two different wordings, I suppose...
One (general) definition and its variation is:
- When an element's oxidation state becomes more positive.
- When an element's oxidation state becomes less negative.
#"Fe"^(2+) -> "Fe"^(3+) + e^(-)#
Here, the half-reaction demonstrates the oxidation state of
And the other (organic) definition and its variation (that I can think of) is:
- When a species gains an oxygen.
- When a species loses a hydrogen.
#"Mn"^(2+) + 2"H"_2"O" -> "MnO"_2 + 4"H"^(+) + 2e^(-)#
You can imagine how to define reduction, the exact opposite of all of these.