What is the oxidation number of oxygen in peroxides?

1 Answer
reudhreghs
Mar 2, 2017

-1

Explanation:

Oxygen almost always has an oxidation number of -2, except in peroxides.

A peroxide is a molecule which includes -O-O-, like hydrogen peroxide, HOOH.

In hydrogen peroxide, the overall charge is 0, so all the oxidation numbers must add up to 0. The oxidation number for hydrogen is always +1, so

HOOH = 0 = 1 xx 2 + X xx 2

where X is the oxidation number for oxygen.

From this, we can deduce that X=-1.

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