calorific value and chemical formula

Question

i got the composition of a biodiesel from CHNS analyser is
C-76.61%, H-12.34% , N- 1.33%, O-9.72% (Oxygen by mass balance from CHNS). (i think the results are of in %volume).
Sample weight - 2.69mg. DENSITY OF SAMPLE -870Kg/m3
HIgher heating value of sample -37534KJ/Kg
1. WHAT IS THE LHV OF THE SAMPLE?
2. CHEMICAL FORMULAE AND MOLECULAR MASS?
3. HOW CAN I GET THE MASS FRACTION OF EACH COMPOUND?

Answer 1

The data is % by mass not volume. The total is 100%, the mass fraction of each element is that listed.

The empirical formula you get by dividing the % mass by the molar mass of the particular elements to get their molar ratios.