Reduced/Oxidized

[805383532]

If you’re not given the charge, how would you know which elements/molecules are reduced or oxidized?

[Andrew Pfeiffer 2E]

You'll have to use your knowledge of valence electrons and charge to determine the charges on individual atoms and ions. From there, use OIL RIG to figure out what's being reduced or oxidized.

[KarineKim2L]

We would need to know the common oxidation states of certain elements, for example O is usually -2 and H is usually +1. Using these and the total charge on the molecule, we can get the oxidation numbers of the transition metals. For example, in MnO4-, the oxidation number of Mn is +7, because the oxygens would make 4(-2)=-8, and the molecule has a total charge of -1, so the Mn has to have an oxidation number of +7. If this molecule became Mn^2+ in the products, you would know that Mn was reduced, as the oxidation number became less positive.

[madawy]

I'm assuming you mean in an equation where the charges are implied but not explicitly stated? In which case you would assign charges to the individual atoms until it adds up to the charge of the entire molecule. You'll see which atoms gain electrons and which lose electrons from one side of the equation to the other. Otherwise, the only method I can think of is basing it on which atoms are most likely to gain/lose (i.e. anions vs cations and the charges certain atoms can and cant hold)

[505316964]

^^^
also, if you start balancing it with H+/OH- and H2O, a charge will pop up and you can tell based off that.

[Martina]

You would have to balance the charges of all the molecules in the equation and see which ones lose electrons making the oxidized and which ones gain electrons making them reduced.