You will learn how to balance oxidation-reduction reactions in neutral, acidic, and basic solutions.
Oxidation-reduction reactions are extremely important in our daily life. A battery is an electrochemical cell in which a redox reaction is occurring and produces the needed voltage for some application. Such cells are called either voltaic cells or galvanic cells.
It is very important that you review the material in Chapter 5 about oxidation-reduction reactions so that you can perform the first step below. The process of balancing an oxidation-reduction reaction can be summarized as follows:
For a neutral solution the above process is very straightforward. In an acidic or basic solution, step 3 requires special treatment. Let's look first at the procedure if the solution is acidic:
3a. Balance all atoms except oxygen and hydrogen. Then balance the oxygen atoms by adding H2O molecules (enough to balance the oxygen atoms) to the side deficient in oxygen. Now add enough hydrogen ions (H+) to the side deficient in hydrogen atoms to balance the hydrogen atoms.
You then proceed with steps 4-7 as above.
Now consider the modification of step 3 if the solution is basic:
3b. Balance all atoms except oxygen and hydrogen. Now balance the oxygen atoms. For every oxygen atom needed, add 2 hydroxyl ions (OH-) to the side needing oxygen atoms, and for every 2 hydroxyl ions added, add one H2O molecule to the other side.
Now proceed with steps 4-7 as above.