Final answer:
The incorrect statement is (d) 'The external pressure is 1 atm.' as the thermochemical equation does not indicate external pressure. Other options (a), (b), (c), and (e) correctly describe the enthalpy change, directionality of the reaction enthalpy, the nature of the reaction as endothermic, and the amount of heat consumed per mole of SO3.
Step-by-step explanation:
The incorrect statement concerning the thermochemical equation 2SO₃(g) → 2SO₂(g) + O₂(g); ΔH° = 198 kJ is option (d) 'The external pressure is 1 atm.' The given thermochemical equation does not provide any information about the external pressure, so we cannot presume the external pressure to be 1 atm based on this equation alone. Now let's discuss the correct options:
- The enthalpy of the reactants exceeds that of the products (a) because the reaction is endothermic (ΔH > 0).
- For the reverse reaction 2SO₂(g) + O₂(g) → 2SO₃(g), the change in enthalpy would have the opposite sign (b), so ΔH° = -198 kJ, indicating an exothermic reaction.
- The reaction is indeed endothermic (c), as indicated by the positive value of ΔH.
- As for the heat consumed, since the equation involves 2 moles of SO₃, for every mole of SO₃(g) consumed, half of 198 kJ, which is 99 kJ, is consumed at constant pressure (e).
Thus, all options except (d) accurately describe aspects of the reaction based on the thermochemical equation provided.