What is the enthalpy of reaction for the following reactions

Question

CO2 + H2 <===> CO + H2O

CO + H2 <===> C + H2O

Answer 1

We need to know the standard enthalpy of formation for the reactants and products in each case.

For H2 in both cases, the value is zero, but we need the values for the other species. Then, when you have those values, you simply take the products - reactants.

So, for the first one...

[∆H_f CO + ∆H_f H₂O] - [∆H_f CO₂] = ∆H_rxn