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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