What is the empirical formula for a compound that is 83.7% carbon and 16.3% hydrogen?

Hello!

We use the amount in grams (mass ratio) based on the composition of the elements, see: (in 100 g solution)

C: 83.7% = 83,7 g 
H: 16.3% = 16.3 g 

Let us use the above mentioned data (in g) and values will be converted to amount of substance (number of moles) by dividing by molecular mass (g / mol) each of the values, lets see:





We note that the values found above are not integers, so let's divide these values by the smallest of them, so that the proportion is not changed, let's see:





Note: So the ratio in the smallest whole numbers of carbon to hydrogen is 3:7, thus, the minimum or empirical formula found for the compound will be:



I hope this helps. =)