What are the oxidation numbers in the compound H2O2?

1 Answer
Jul 2, 2014

Answer:

The oxidation number of #"H"# is +1. The oxidation number of #"O"# is -1.

Explanation:

You assign oxidation numbers to the elements in a compound by using the Rules for Oxidation Numbers.

The important rules for this problem are:

  1. The oxidation number of #"H"# is +1, but it is -1 in when combined with less electronegative elements.

  2. The oxidation number of #"O"# in compounds is usually -2, but it is -1 in peroxides.

  3. The sum of the oxidation numbers of all the atoms in a neutral compound is 0.

The oxidation number of #"H"# is +1 (Rule 1).

If you know that #"H"_2"O"_2# is hydrogen peroxide, you can immediately assign oxygen the ON = -1.

If you don't know that #"H"_2"O"_2# is hydrogen peroxide, you can use Rule 3.

The oxidation number of #"H"# is +1. For two #"H"# atoms, the sum is +2.

Since #"H"_2"O"_2# has no charge, the total oxidation number of the two #"O"# atoms must be -2.

The oxidation number of one oxygen atom must be -1.