Balancing Chemical Equations (For Dummies)

A lot of people find balancing chemical equations an unconquerable feat. Here I’ll show you in a simple manner how easy they can really be.

1) The Law of the Conservation of Atoms states that all atoms that go into a chemical equation must come out.
So look at this balanced equation for potassium chloride.
K+Cl —> KCl
Potassium (K) has a charge of positive one. Chloride has a charge of negative one. For the equation to work, both have to cancel each other out. You can find out the charges by looking at the periodic table. This is a fairly simple example of a chemical equation. They can get a lot more complex.

2) Subscripts
You can never change subscripts in a chemical equation. This equation is a bit harder, but you can see how to get more atoms when you need them.
H₂O+Fe —> Fe₂O₃+H₂
The first thing you need to do to solve this equation is to count the number of each type of atom on both sides.
There are two hydrogen atoms on the left, and two on the right. Balanced.
There is one oxygen atom on the left, and three on the right. Unbalanced.
There is one iron atom on the left, and two on the right. Unbalanced.
Now, we cannot change the subscripts, but, we can add a number in front of an atom to multiply the number we already have.

When an atom is in a group, such as hydrogen and oxygen on the left and iron and oxygen on the right, you cannot multiply one specific atom in the group. The whole group has to be multiplied. If the atom is alone, such as the iron on the left and the hydrogen on the right, you can just multiply that atom.

To start the process, we would need to put a three in front of the H₂O on the left, to get three oxygen atoms. But, keep in mind this also will give you six hydrogen atoms. (Two times the three.)
This will bring your equation to look like this:
3H₂O+Fe —> FeO₃+H₂
The equation is not yet balanced, since we now have an uneven number of iron and hydrogen atoms. To fix this, we will put a two in front of the Fe on the left, to give you the proper number of iron atoms. Then, we will put a three in front of the hydrogen on the right, to give the proper number of all atoms. Your equation should now look like this.
3H₂O+2Fe —> 2FeO₃+3H₂ Balanced!

Now, what if the equation you’re balancing has parenthesis? I’ll show you.
Let’s take this unbalanced equation, Al₂(SO₄)₃+Ca(OH)₂ —> Al(OH)₃+CaSO₄
As you can see, we have two aluminum atoms on the left, and one on the right. Unbalanced.
Three S atoms on the left, one on the right. Unbalanced.
Twelve O atoms on the left, and four on the right. Unbalanced.
One Ca atom on the left, and one on the right. Balanced.
Two OH atoms on the left, and three on the right. Unbalanced.

The reason why there are so many S atoms on the left is because, to start, there were four. Then, they are multiplied by the number outside the parentheses. The other atom that is inside the parentheses, S, is only three because there was only one to start.

To start, we’d need to put a two in front of the Al atom on the right, to get the proper number of Al atoms for both sides. This will also give us six O and H atoms. To fix this, we will need to put a three in front of the Ca atom on the left side of the equation. This will give us the proper number of both O and H atoms, but also three Ca atoms. To balance the whole equation, you will need to put a three in front of the Ca atom on the right. Your equation should now look like this.
Al₂(SO₄)₃+3Ca(OH)₂ —> 2Al(OH)₃+3CaSO₄ Balanced!

When balancing chemical equations on your own, don’t forget, a little patience goes a long way. Some are a lot more complex then the ones in this guide, but some can be a lot easier, too. Just don’t forget this guide, and you should be fine. Happy balancing!