[LHM]

Given the reactions:
CH₄(g) + 2O₂(g)  CH₂O(g) + 2H₂O(g)    :delta: H°= -890.4 kJ
CH₂O(g) + O₂(g)  CO₂(g) + H₂O(g)    :delta: H°= -563.5 kJ

What is the :delta: H° for the reaction CH₄ + O₂(g)  CO₂(g) + H₂O(g)?

A) -1453.9 kJ
B) -326.9 kJ
C) -236.6 kJ
D) +118.3 kJ

I tried changing the two equations so that you could add them together and get the :delta: H°, but the closest I got was CH₄(g) + 3O₂ CO₂(g) + 3H₂O(g), so how do you do this? The answer's supposedly B.

[Borek]

What is the :delta: H° for the reaction CH₄ + O₂(g)  CO₂(g) + H₂O(g)?

There is no such reaction, so there is no delta H.