Enthalpy and catalysts?

Question

I'm not sure if whoever wrote my chemistry text book just sucks at chemistry, or if they completely forgot to mention something. In reactions where a chemical catalyst is involved (i.e. CH4(g) + H2O(g) >>> nickel catalyst >>> CO(g) + 3H2), are you supposed to do something different to figure out delta H rather than just using "Delta H = sigma n delta H (products) - sigma n delta H (reactants)"?

Because for the question I mentioned above I keep getting delta H as 205.7 kJ, but the book says it is supposed to be 249.7 kJ.

This has happened to me with two questions in there involving chemical catalysts so far... Are the answers in my book just wrong?

Any help would be greatly appreciated.

Answer 1

A catalyst does not alter the enthalpy change of a reaction, so that is not the problem.

I suggest that you should check whether you used the enthalpy change of formation of liquid water, or gaseous water. That is a frequent mistake that students make.