What is the oxidation number of oxygen in hydrogen peroxide?

1 Answer
Jan 6, 2017

In hydrogen peroxide, the oxidation number of each oxygen is #-I#.

Explanation:

Oxidation number is the charge left on the central atom, when all the bonds are broken with the charge assigned to most electronegative atom.

With #H-O-O-H#, we break a #H-O# bond, and get #H^+# and #""^(-)O#. However, if we break an #O-O# bond the 2 electrons in the #O-O# bond are SHARED between the oxygen atoms, to give #2xx*O^-#; i.e. the oxygen atoms necessarily have the same electronegativity.