TEST STRATEGY
When balancing equations, it is in general more effective to focus on the least represented
elements (often the heavier ones).
Example: Balance the following reaction.
C 4 H 10 (l) + O 2 (g) → CO 2 (g) + H 2 O (l)
Solution: First, we can balance the carbons in reactants and products because carbon is the
least represented and heaviest element.
C 4 H 10 + O 2 → 4CO 2 + H 2 O
Second, balance the hydrogens in reactants and products because hydrogen is the
second least represented element in the equation.
C 4 H 10 + O 2 → 4CO 2 + 5H 2 O
Third, balance the oxygens in the reactants and products.
2C 4 H 10 + 13 O 2 → 8 CO 2 + 10 H 2 O
Finally, check that all of the elements, and the total charges, are balanced correctly.
We could have balanced the elements in a different order, although in general it is
easier to tackle the least represented atoms first.
