Explain how to balance equations

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.

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