Example of Balancing Equations:

FeS₂ + O₂→    Fe₂O₃+ SO₂

Solution:

Starting with Fe₂O₃ (see guideline b), write 2FeS₂ + O₂→ 2Fe₃O + SO₂, which balances the Fe on each side of the equation.

 Present there are 4 S atoms on the left side so balance the S atoms throuogh writing

 2FeS₂ + O₂ → Fe₂O₃ + 4SO₂

 Everything is balanced except the O.  There are now 11 O atoms on the right and 2 O atoms on the left.  To get 11 O atoms on the left write

2FeS₂ + 5.5O₂ → Fe₂O₃ + 4SO₂

This makes both sides of the equation balanced except the coefficients have to be whole numbers (guideline f). For meet guideline f, multiply both sides through two that will bring the left side to an all number of O₂ molecules.

Therefore, the solution is 4FeS₂ + 11O₂→ 2Fe₂O₃ + 8SO₂