What is the empirical formula of the hydrocarbon?

Mesitylene a hydrocarbon that occurs in small amounts of crude oil, has an empirical formula of C3H4.?

• Mesitylene a hydrocarbon that occurs in small amounts of crude oil, has an empirical formula of C3H4. The experimentally determined molecular weight of this substance is 121 amu. What is the molecular formula of mesitylene?

• Answer:

  The molecular weight of the empirical formula is 40.06. This is found by summing the atomic weights multiplied by the numbers of atoms: 3*12.01 + 4*1.008 = 36.03 + 4.032 = 40.062 Next, divide the experimentally determined molecular weight by the calculated atomic weight to get the multiplication factor (rounded to the nearest integer): 121/40.062 = 3.020 = 3 Next, multiply the atomic coefficients by this integer to get the molecular formula: (C3H4)*3 = C9H12