I'm very confused with Hess's Law. I need to answer the following question:
Calculate the enthalpy change for the following reactions given the values of enthalpy change of formation.
a) 2Al + Fe2O3 --> 2Fe + Al2O3
b) 2CO + O2 --> 2CO2
Values given:
Al2O3 = -1669
Fe2O3 = -822
CO2 = -393
CO = -111
For b, I came up with an answer of -564kJmol^-1 but I'm unsure whether this is correct.
Any help would be greatly appreciated!