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The Empirical Formula

    The empirical formula shows the lowest whole number ratio of the elements in a compound (the simplest formula of a compound).

Step 1
When you are given the percent composition, you assume that the percentage is grams (g). So 14.9% = 14.9 grams.

Step 2
Convert the grams to mols

Example:  14.9 g of H = 1 mol/1.01 (Atomic mass) = 14.8 mols.

Step 3
Find the ratio.

Example: H14.8  O2.0

Divide both sides by the lowest number that is visible. So 2 is the lowest number visible.

Example: H14.8   O2.0    
                     --------   --------   --> H7.4  O1    --> H7O (This is your final
                      2.0        2.0                                                answer. We rounded
                                                                                           7.4 to 7.)