Table of contents

This is an oxidation-reduction (redox) reaction:

Cu0 - 2 e- → CuII (oxidation)

O0 + 2 e- → O-II (reduction)

Cu is a reducing agent, O is an oxidizing agent

Word equation


copper + oxygen → cupric oxide

Input interpretation


Cu + O2 → Cuo

 copper oxygen cupric oxide

Balanced equation

Balance the chemical equation algebraically:

Cu + O2 → CuO

Add stoichiometric coefficients, c, to the reactants and products:

c1 Cu + c2 O2c3 Cuo

Set the number of atoms in the reactants equal to the number of atoms in the products for Cu and O:

Cu: c1=c3

O: 2c2=c3

Since the coefficients are relative quantities and underdetermined, choose a coefficient to set arbitrarily. To keep the coefficients small, the arbitrary value is ordinarily one. For instance, set c2 = 1 and solve the system of equations for the remaining coefficients:


c2=1 c3=2

Substitute the coefficients into the chemical reaction to obtain the balanced



2 Cu + O2 → 2CuO