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

Explanation:

First, you need to be sure the elemental analysis has identified all the components.

83.7+16.3=100% so we’re good, and the same ratio works for the formula,

The formula is CxHy, so x*12+y*1= 100% of the empirical formula wt, which we’ll use later to confirm the elemental analysis. We need x and y

Then x = 83.7/12 is 6.975 and being savvy, we guess it’s supposed to be 7, since empirical formulas use whole numbers if they can. Likewise y=16.3/1 = 16.3, and now we round down to the nearest whole number (16), making our empirical formula C7H16

Check:

7*12+16*1=100 (the empirical formula wt) 84/100=0.84 and 16/100=0.16 This is close enough, so C7H16 is the empirical formula.