Can someone help me with this question please?

Question

CH4(g) + 2 O2(g) --> CO2(g) + 2 H2O(g)

The value of ΔH° (heat of formation) is –802.4 kJ/mol. Can you explain quantitatively the origin of the difference between this value and -890.0 kJ/mol given above?

Thank you!

Answer 1

I would say that the person who solved the problem used the ΔH value for H₂O liquid instead of H₂O gas. For two moles the value is just about equal to the difference between -802.4 and -890.0 kJ/mol