oxidation states

[KVS]

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WHY is the oxidation state of oxygen -1 in peroxides?

TPR gives H2O2 and Na2O2 as examples. In the first, I understand that since Oxygen is more electronegative than carbon, Hydrogen assumes an oxidation state of +1, leaving O to assume an oxidation state of -1.

What if the element bonded to the two oxygens in peroxide did not have an oxidation state of +1? Does anyone know any examples?
Thanks

 

[Jepstein30]

WHY is the oxidation state of oxygen -1 in peroxides?

TPR gives H2O2 and Na2O2 as examples. In the first, I understand that since Oxygen is more electronegative than carbon, Hydrogen assumes an oxidation state of +1, leaving O to assume an oxidation state of -1.

What if the element bonded to the two oxygens in peroxide did not have an oxidation state of +1? Does anyone know any examples?
Thanks

The "real" way to determine oxidation state is:

*real as in not using the shortcut rules

Oxidation state = (# of bonds with more EN atoms) - (# of bonds with less EN atoms).
Typically, like in H2O, oxygen is the most electronegative atom. In water, oxygen is bonded to two LESS EN hydrogens so the oxidation state is -2.

In H2O2, each oxygen is bonded to one hydrogen and one oxygen. Therefore, it's only bonded to one LESS EN atom and has an oxidation state of -1.

So it doesn't have to do with the oxidation states of other atoms.. just the relative EN values which you can figure out based on periodic trends.

 

[KVS]

That really helped. Thanks a lot!