I am doing high school chemistry and I am busy working with redox reactions.

The explanation in my text book, of how a redox reaction works, left me a bit confused as to how many atoms can be reduced/oxidized in a single reaction equation.

Can only one atom (species) be reduced/oxidized in a single equation or can there be more than one reduced/oxidized in the same chemical equation?

All of the reaction equations I have come across so far have just one atom reduced and one atom oxidized, for example:

$$ \ce {Mg(s) + 2HCl(aq) -> H_2(g) + MgCl_2(aq)} $$

In this reaction only Mg is oxidized and only H is reduced. Is there a reaction in which more than one species of atom it reduced or oxidized?

  • $\begingroup$ Redox reactions can be much more complicated then that. $\endgroup$
    – Mithoron
    Commented Oct 12, 2017 at 14:27
  • $\begingroup$ I know they get much more complex. I am not doing very complex ones yet. I just chose a simple one to try illustrate my question, which is a very simple question. $\endgroup$
    – user53273
    Commented Oct 12, 2017 at 14:33
  • 1
    $\begingroup$ Yes, there can be more and yes/no questions are suitable for this site. $\endgroup$
    – Mithoron
    Commented Oct 12, 2017 at 14:36
  • $\begingroup$ Thanks. That really helps. I think my text book spoke as if only one could be reduced/oxidized at a time because I would not need to do more complex ones yet. Unfortunately I don't have enough reputation to up-vote you :-( $\endgroup$
    – user53273
    Commented Oct 12, 2017 at 14:42
  • 2
    $\begingroup$ I'd rather point out that the reactions in which multiple elements get oxidized/reduced are a relative minority (in school chemistry, at least). True, you'd encounter pretty complex reactions further on, but their complexity stems from other reasons; despite it, most of the times there would be only one oxidant and one reducing agent. $\endgroup$ Commented Oct 12, 2017 at 14:50

1 Answer 1


I'm not sure if I understand your question correctly, but consider the reaction

$$\ce{CH3-SH + 3 O2 -> SO2 + CO2 + 2 H2O}$$

where methanethiol is oxidized with oxygen to sulfur dioxide, carbon dioxide, and water.

Thereby the oxidation states of sulfur and carbon change from $-2$ to $+4$ and the oxidation state of oxygen from $\pm0$ to $-2$. So sulfur and carbon atoms are both oxidized while oxygen is reduced.

I hope this answers your question.

  • $\begingroup$ @adventurin: This did answer the question, thank you. The example equation helped. By the way, any suggestions on how to make the question clearer would be appreciated. $\endgroup$
    – user53273
    Commented Oct 13, 2017 at 11:18

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