# Balancing a Chemical Equation

The number of atoms on each side of a chemical equation must be equal.

To balance a chemical equation the following rules must be followed:

–**After you have written a chemical equation check to see if the equation is balanced (have the same number of atoms of each element on each side)**.

–**If it is not balanced then the smallest possible number must be placed in front of the reactants and/or products to ensure it is balanced on either side.**

Let’s look at the following equations:

C_{(s)} + O_{2 (g) }_{→}CO_{2 (g)}

The equation above is balanced as you can see there are an equal number of carbon and oxygen atoms on either side.

H_{2 (g)} + O_{2 (g) }→ H_{2}O_{(l)}

This equation above is not balanced. Let’s look at the left and right sides of the equation and count the number of hydrogen and oxygen atoms. **There are 2 hydrogen atoms and 2 oxygen atoms on the left side of the equation and there are 2 hydrogen atoms and one oxygen atom on the right side.**

If we follow the rules from above, we must add the smallest possible number in front of the products and/or the reactants to ensure it is balanced on either side.

The balanced equation is:

2H_{2 (g)} + O_{2 (g) }→2H_{2}O_{(l)}

Here is another example:

Fe_{(s)} + Cl_{2 (g) }→FeCl_{3(s)}

The equation above is not balanced.

The balanced equation looks something like this:

2Fe_{(s)} + 3Cl_{2(g) }→2FeCl_{3(s)}