Use the following information: [[[[2H2(g) + O2(g) → 2H2O(l) ∆H = −572 kJ mol−1]]]] [[[[2H2(g) + O2(g) → 2H2O(g) ∆H = −484 kJ mol−1]]]] to calculate the enthalpy change for the process: H2O(g) → H2O(l)

Well the method I use for calculations in thermochemistry is a little different from the textbooks but is far easier to understand. 

I would approach this question by drawing out the chemical equations in a pyramid shape and putting arrows in correct place with the right values next to it. Then explain what the question is asking you to find out and rearrange the arrows in order for the answer to be ascertained.

Draws diagram explaining it