Need pointed in the right direction for the following type of equations please.

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Given the following equation for the burning of propane gas:

C3H8(g) + 5O2(g)--> 3CO2(g) + 4H2O(l) (changes in Enthalpy) = -2220kJ mol-1

Calculate the energy in kJ liberated when 78.6g of propane is
combusted in the presense of excess O2.

Please show me workings for how you get to your answer. So I can get
on top of this one. Cheers.

mol C3H8 = 78.6/molar mass = 78.6/44 = 1.786 mol
energy released, i.e. change in Enthalpy = -2220kJ/mol
Therefore: -2220kJ/mol X 1.786 mol = -3964.92 kJ

Great!!

Thanks alot.