Question

How would you define oxidation and reduction in terms of gain or loss of electrons, gain or loss of hydrogen (in a covalent bond), and gain or loss of oxygen?

Answer 1

See here for the rules....

Explanation:

Oxidation is conceived to be the loss of electrons (according to the given scheme) or the loss of hydrogen. And likewise reduction is conceived to be the GAIN in electrons, or AN increase in the number of hydrogens to which a species is bound....

For the reaction of carbon and oxygen to give carbon dioxide, carbon is said to the be `"oxidized"`...

`C(s) +2H_2O(l) rarr CO_2(g) +4H^+ +4e^(-)` ....

....and oxygen is said to be reduced....

`O_2(g) + 4H^++4e^(-) rarr 2H_2O(l)`

We add the half-equations together in such a way that the electrons are eliminated....

`C(s) +cancel(2H_2O(l)) +O_2(g) + cancel(4H^++4e^(-))rarr CO_2(g) +cancel(4H^+ +4e^(-)+2H_2O(l))`

`C(s) +O_2(g) rarr CO_2(g)`

Which of course is the same as we would have had we balanced the equation conventionally, (balance the carbons, then the hydrogens, and then the oxygens.)

See here for another example.