the standard enthalpy of formation of CO(g)

Question

A scientist measures the standard enthalpy change for the following reaction to be 200.6 kJ:

CH₄(g) + H₂O(g)3H₂(g) + CO(g)

Based on this value and the standard enthalpies of formation for the other substances, the standard enthalpy of formation of CO(g) is 

Answer 1

You need a table of ΔΗ_f for the CH₄ and CO and H₂O_(g). Since one isn't provided, I will use the values from my table.

ΔH_f for CH₄ = -74.8 kJ/mol and CO = -110.5 kJ/mol and H₂O_(g) = -241.82 kJ/mol

ΔH_rxn = (3 H₂ + CO) - (CH₄ + H₂O) = [ 3 (0) + (-110.5)] - [(-74.8) + (-241.82)] = + 206.12 kJ