What is the oxidation half-reaction for 2Mg O2 2MgO?

Answer 1

Mg equals Mg2+ plus 2e-

Answer 2

Mg equals Mg2+ plus 2e-

Answer 3

Mg Mg2+ 2e

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Answer 4

All elements are assigned an oxidation number of zero. Ions have an oxidation number equal to their charge. Therefore oxygen goes from "0" to "-2" in the reaction and a decrease in oxidation number is reduction. Similarly, the magnesium has gone from zero (elemental) to +2 as an ion. This is an increase and hence oxidation. There are a number of other (simpler) ways of expressing redox but this covers all types of redox - even when oxygen is not involved.

Answer 5

O2+4e- 2O 2-

Answer 6

Mg equals mg2+ +2e-

Answer 7

Mg equals Mg2+ plus 2e-