"Synthesis gas" is a mixture of carbon monoxide and hydrogen that is used to synthesize a variety of organic compounds. One reaction for producing synthesis gas is 3CH4 + 2H2O + CO2 = 4CO + 8H2

Question

Using enthalpies of formation, calculate the enthalpy change for this reaction in kJ/mol.

Answer 1

Look up the delta Hf in your text or notes, then
delta Hrxn = (delta H products)-(delta H reactants). H2 will be zero. Therefore, it is
DHrxn = (4*DHof CO)-(3*DHCH4+2*DHH2O+DHCO2)

Answer 2

I ended up getting 747.5 kJ/mol

(4*-110.5) - (3*-74.81) + (2*-285.8) + (-393.5)
-442 + 1189.53 = 747.53 kJ/mol

Answer 3

You didn't write the states of the materials in the equation. I didn't look up any of the numbers but I recognize H2O as being in the liquid state. I'm wondering if this reaction you wrote isn't supposed to be gaseous state for H2O and/or at an elevated temperature (which would make it a gas). If it is you need to check all of your numbers to make sure you have them correct.