[Sophia7X]

Consider
C3H8(g) + 5 O2(g) --> 3 CO2(g) + 4 H2O(l)
2C4H10(g) + 13 O2(g) --> 8 CO2(g) + 10 H2O(l)

              Standard ΔHf    Cp
Propane: -103.8 kJ/mol.       73.6 J/molK
Butane:   -125.7.                 140.6
CO2:       -393.5.                 37.1
H2O(l):    -285.8.                 75.3
H2O(g):    -241.8.                33.6
O2:           0.                        29.4
N2:           0.                        29.1

Products are produced at 100° C and standard P. Reactants react at standard conditions.
Calculate the combustion E for burning 1 mol C3H8 and C4H10.




So I got standard ΔHf for propane and butane to be -2220 and -2877 kJ/mol respectively.
I know that you're supposed to use ΔH(Temp) = ΔH standard + (Temp-273 K)Cp to convert  ΔH but what numbers do I use for Cp? Am I supposed to do sort of a products - reactants type of thing for a reaction's Cp or add them all up?

Also, water is vaporized at 100°C and standard ΔH vaporization = 44 kJ/mol. How do I account for this info in my calculation? Thanks.