Now let me tell you how to balance equations using oxidation number.  Though in our previous lessons in Chemistry we have learned how to balance chemical equations in which the number of atoms of the reactant must be equal to the number of atoms of the product.

           

            But what if we can’t easily balance a redox reaction? What shall we do? Simply use the Oxidation Number Method.

 

Let’s try solving this one:

Cu(s) + Ag+(aq) → Cu2+(aq) + Ag(s)

           On the reactant side we can see that copper has no oxidation number while Silver has an oxidation number of one.

            

           On the right side the oxidation number of Copper became 2 and Silver became 0.

 

 

 

 

 

 

 

Now we have to think of a number that when we multiply to both.

 

 

 

 

 

 

 

 

 

 

So the balanced chemical equation is 1 Cu(s) + 2Ag+(aq) → 1 Cu2(aq) + 2Ag(s)