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) + O2 (g) → CO2 (g)
The equation above is balanced as you can see there are an equal number of carbon and oxygen atoms on either side.
H2 (g) + O2 (g) → H2O (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:
2H2 (g) + O2 (g) → 2H2O (l)
Here is another example:
Fe(s) + Cl2 (g) → FeCl3(s)
The equation above is not balanced.
The balanced equation looks something like this:
2Fe(s) + 3Cl2(g) → 2FeCl3(s)