Question

Ibuprofen is 75.69% C, 8.80% H, and 15.51% O by mass. It has a molar mass of 206 g/mol. Find the empirical and molecular formula.

Answer 1

You take each element and take the percents and convert to grams but it is the same as the percents so C=75.69 H= 8.80 O=15.51
you then multiply like this
75.69x (1mol/12.01)=6.3022
8.80x(1 mol/1.01)=8.712
15.51x(1 mol/15.9)=.97547
you then divide all you asnwers by the smallest quanity .97547
you then should get
C=6.5 H=9 O=1
we can only have whole numbers so multiply by 2
C=13 H=18 O=2
because you already multiplied this is your molecular and empircal formula
C13H18O2 is your final answer