# What is the meaning of fractional coefficients in reaction equations? [duplicate]

There is a chemical reaction describing the oxidation of $\ce{Fe3O4}$ (magnetite) to $\ce{Fe2O3}$ (hematite). It is: $$\ce{2Fe3O4 (s) + 1/2 O2 (g) ->[\Delta] 3 Fe2O3 (s)}$$ My question is what does $\ce{1/2 O2}$ mean? Is it like a single oxygen atom or what and if it is why not just typing $\ce{O}$ instead of $\ce{1/2 O2}$?

## marked as duplicate by Jan, andselisk♦, bon, Mithoron, TyberiusOct 24 '17 at 14:27

Although by definition, it means that for every two $\ce{Fe3O4}$ molecules you need half an oxygen molecule, this does not translate to the real world, as you either have one or more molecules, or none at all.
$$\ce{4Fe3O4 (s) + O2 (g) ->T[heat] 6Fe2O3 (s)}$$
• @wolphram While I agree with your sentiment of the criticising that $\ce{Fe3O4}$ is not a molecule, referring to the amount of substance as moles is at least equally as wrong. – Martin - マーチン Oct 24 '17 at 8:18