Question

How do find oxidation numbers with respect to carbon in an unsaturated molecule?

Answer 1

Are you asking how to find the oxidation numbers of `C` in a molecule of, say, `"propane"`?

Explanation:

Well, as for any neutral molecule or salt, the sum of the oxidation numbers is `"zero"`. The oxidation number of hydrogen is usually `+I` and it is here. Because the electrons in an element-element bond (i.e. in a `C-C` bond) are conceived to be shared, this gives for propane, `H_3C*+:CH_2+*CH_3`, i.e. oxidation numbers of `2xx-III" + "-II`. The average oxidation number of `C` is `-8/3`.

When these carbons are oxidized to carbon dioxide, what is their oxidation number? See here for other examples.