Carbon Oxygen Hydrogen Compound?

Question

A compound contains only carbon C, hydrogen H, and oxygen O. When 6.737 grams of this compound is burned completely in air, 16.156 grams of CO2 and 3.307 grams of H2O are produced. What is the empirical formula of this compound?

If the molar mass of the compound described in the previous question is 275.3, what is its molecular formula?

Answer 1

? mol C = 16.156 g CO2 / 44.010 g CO2 = 0.367
? g C = 0.367 x 12.011 = 4.41

? mol H = 3.307 g H2O x 2 / 18.02 g H2O = 0.367
? g H = 0.367 x 1.008 = 0.370 g

? g O = 6.737 - ( 4.41 + 0.370) = 1.96
? mol O = 1.96 / 15.999 = 0.122

We Have C (0.367) H (0.367) O (0.122)
We divide by the smallest number and we get :
C3H3O Empirical formula ( mass = 55.03 )
275.3 / 55.03 = 5
To get the molecular formula we multiply by 5
C15H15O5

Answer 2

Moles of CO2 = 16.156/44

Moles of H = 3.307/9

in 6.737 g

Extend to 1 mole or 275.3 g and solve.