How do you find the oxidizing agent in a reaction?

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Answer 1 · 2017-08-19T21:23:25

The oxidizing agent is FORMALLY the species that is reduced.........

See this old answer for the formal rules of oxidation numbers. We conceive that a species, an atom LOSES electron upon oxidation.

And thus for the oxidation of methane.....

$CH_4(g)+O_2(g) rarr CO_2(g) + 2H_2O(l)$

We can put in oxidation numbers if we like.....

$CH_4(g)+O_2(g) rarr CO_2(g) + 2H_2O(l)$

$C(-IV) + O(0) rarrC(+IV) + 4xxO(-II)$

A formal EIGHT electron oxidation.

We could formalize this process even further by writing the separate redox reactions:

$CH_4 +2H_2O rarr CO_2 +8H^+ +8e^-$ $(i)$

$O_2 +2H^(+) + 2e^(-)rarr H_2O$ $(ii)$

$4xx(ii) + (i)$ gives the balanced combustion reaction.