Textbook Problem 4D.15

[Cadence Chang]

Hi, can someone please explain how to do textbook problem 4D.15?

Determine the reaction enthalpy for the hydrogenation of ethyne to ethane, C2H2(g) + 2 H2(g) -> C2H6(g), from the following data:
dHc° (C2H2, g) -1300. kJ/mol, dHc°(C2H6, g) -1560. kJ/mol, dHc°(H2, g) -286 kJ/mol.

I wrote out the formulas for the combustion of each reactant and product, then used the combustion values to solve for the heat of formation using ∆Hrxn (combustion) = ∑Hf products - ∑Hf reactants. From there, I used the calculated heat of formations to solve for the overall reaction. I'm not sure if I'm approaching the problem correctly though because I can't seem to get the correct answer. Thanks!

[Anna Turk 1D]

Hi! I believe this is the correct approach to the question. Make sure that you multiply the deltaH of H2 by 2, given that there are two moles H2. Hope this helps!