This instructable will show how to balance a chemical equation. Balancing a chemical equation is important because there must be the same number of atoms on the initial side of the equation as well as on the final side of the equation. The same number of atoms on each side follows the concept of the Law of the Conservation of Mass, which states that matter cannot be created nor destroyed.
In order to complete this instructable, you should have a good knowledge of the identifying elements and doing simple math like addition and multiplication.
You will need:
Step 1: Make a Table
In a chemical equation there are subscripts and coefficients. The subscripts tell you how many atoms are in a compound while the coefficient tells you how many moles/molecules are of the chemical. If there isn't a subscript present next to the element, it implies that there is only one atom present.
(see figure 1 for an example)
1. Under the chemical equation, make a simple chart with the elements listed.
a. Next to each element, write the number of atoms present in the unbalanced chemical equation.
Hint: remember the subscript tells you how many atoms are present
b.If the element is in multiply molecules on one side, write each number separate from each other then add them up
(see figure 2)
Step 2: Determining and Balancing the First Element
1. Pick an element that appears in one molecule on the left side and in one molecule on the left.
a. Leave hydrogen and oxygen for last because they are more often found in more than one chemical on each side of the equation.
b. For a more complicated example that has more than one element besides Oxygen or Hydrogen, pick the element that has more atoms on one side compared to the other.
See figure 3
2. Once you've determined which element to balance first, add a coefficient to balance that element by multiplying the subscript by the coefficient added.
a. Adjust the table by multiplying each element effected by the coefficient added to that molecule.
b. Since you had 7 Carbons on the left and 1 Carbon on the right, you are going to need to have a 7 as the coefficient on the right.
c. Since the Carbon molecule also has oxygen in it, you need to multiply the 7 by the number of atoms with Oxygen which is 2 to get a total of 14.
i. There is also another Oxygen, but it is in a different molecule so you need to add it to the 14 to get a total of 15 atoms for Oxygen.
See figure 4
3. Repeat this step for the rest of the elements except for Hydrogen and Oxygen
Step 3: Balancing Hydrogen
Once you have balanced all the other elements, it is now time to balance the hydrogen atoms.
1. Balance the Hydrogen with the least amount of atoms.
a. In the example, that would be the Hydrogen on the right side of the equation.
2. Place a coefficient number needed in order to balance the Hydrogen to the other Hydrogen with the highest amounts of atoms.
a. In the example, a 8 would be needed in order to balance the Hydrogen on the right side to the Hydrogen on the left side as pictured in figure 5.
3. Adjust the table by multiplying each element effected by the coefficient added to that molecule.
a. Since the Hydrogen on the left is with an Oxygen, the 1 Oxygen atom needs to be multiplied by 8 and added to the 14 atoms already there due to the 7 in CO2 so 22 atoms of Oxygen total as seen in figure 6.
Step 4: Balancing Oxygen
1.Balance the Oxygen with the least amount of atoms.
a. In this example, it would now the right side with 22 atoms because of the coefficients added.
2. Place a coefficient number needed in order to balance the Oxygen to the other Oxygen with the highest amounts of atoms
b. 11 would now be needed to balance the Oxygen on the left with the Oxygen to the right and can be seen in the figure 7.
Now you have successfully balanced a chemical equation!