Balancing of a chemical equation
- Write down your given equation. For this example, you will use: C3H8 + O2 –> H2O + CO2
- Write down the number of atoms per element.
- Left side: 3 carbon (C3), 8 hydrogens (H8) and 2 oxygen (O2).
- Right side: 1 carbon (C), 2 hydrogens (H2) and 3 oxygen (O + O2)
- Save hydrogen and oxygen for last, as they are often on both sides. Hydrogen and oxygen are both common in molecules,
- Start with single elements. If more than one element left to balance, select the element that appears in only a single molecule of reactants and in only a single molecule of products.
- Use a coefficient to balance the single carbon atom. Add a coefficient to the single carbon atom on the right of the equation to balance it with the 3 carbon atoms on the left of the equation. The coefficient 3 in front of carbon on the right side indicates 3 carbon atoms just as the subscript 3 on the left side indicates 3 carbon atoms.
- Balance the hydrogen atoms next. You have 8 on the left side. So you’ll need 8 on the right side. When you multiply the coefficient 4 times by the subscript 2, you end up with 8. The other 6 atoms of oxygen come from 3CO2.(3×2=6 atoms of oxygen+ the other 4=10)
C3H8 + O2 –> 4H2O + 3CO2
- Balance the oxygen atoms. now have 4 oxygen atoms in the water molecules and 6 oxygen atoms in the carbon dioxide molecules. That makes a total of 10 oxygen atoms.
C3H8 + 5O2 –> 4H2O + 3CO2.