Question

C2H5OH(l) + 3 O2(g) -> 2 CO2(g) + 3 H2O(g)

During an experiment 10.00 g of ethanol is completely
burned in air to release CO2(g) and H2O(g) as shown in
the equation above. During the combustion, 296.6 kJ of
heat energy is released. What is the molar enthalpy of
combustion, H˚comb?

(A) –2966 kJ•mol–1

(B) –1366 kJ•mol–1

(C) –64.36 kJ•mol–1

(D) –29.66 kJ•mol–1

I am unsure on how B is the correct answer. I have never been taught over this, I am preparing for Chemolympiad.

Answer 1

C2H5OH + 3O2 ==> 2CO2 + 3H2O
delta Hcomb = -296.6 kJ.
So you have 296.6 kJ released for 10 g; you want to know how much is released for 1 mol (46.07g); therefore,
dH = -296.6 x 46.07/10 = ?