4FeS2 + 11O2 yields 2Fe2O3 +8SO2. I don't understand this equation. FeS2 leads me to believe that the Fe here has a charge of +2 but in the product it appears to have a charge of +3 judging by the formulas. How is this possible and what is this equation representing?

Question

4FeS2 + 11O2 yields 2Fe2O3 +8SO2.  I don't understand this equation.  FeS2 leads me to believe that the Fe here has a charge of +2 but in the product it appears to have a charge of +3 judging by the formulas.  How is this possible and what is this equation representing?

DrBob222 · Accepted Answer

You have written an oxidation-reduction kind of equation. They are VERY common. And your perception is correct, Fe has gone from an oxidation state of +2 to an oxidation state of +3. It makes that move by losing electrons and that is defined as oxidation (the loss of electrons). If something is oxidized, something else must be reduced. What is it in this equation? O2 goes from an oxidation state of zero on the left to -2 on the right, which is a gain of electrons and that is defined as reduction. I hope this helps.