A hydrocarbon is #83.33%# by mass with respect to carbon. What is (i) its empirical formula, and (ii) its molecular formula if the hydrocarbon has a mass of #72*g*mol^-1#?
As always with these problems it is useful to ASSUME a mass of
We divide thru by the lowest molar quantity (
Now the MOLECULAR FORMULA is always a WHOLE number multiple of the EMPIRICAL FORMULA, and since we know the molecular mass: