Which of the following statements is incorrect concerning the thermochemical equation below?
2SO3(g) 2SO2(g) + O2(g); H° = 198 kJ
a. The enthalpy of the reactants exceeds that of the products.
b. The reaction is endothermic.
c. For the reaction 2SO2(g) + O2(g) 2SO3(g), H° = –198 kJ.
d. The external pressure is 1 atm.
e. For every mole of SO3(g) consumed, 99 kJ of heat at constant pressure is consumed as well
To determine which statement is incorrect concerning the given thermochemical equation, we need to analyze each statement individually.
a. The statement "The enthalpy of the reactants exceeds that of the products" is incorrect. Enthalpy (heat content) is released during an exothermic reaction and absorbed during an endothermic reaction. In this equation, the product side has higher enthalpy than the reactant side, indicating an endothermic reaction. So, statement a is incorrect.
b. The statement "The reaction is endothermic" is correct. As mentioned earlier, the given equation shows the absorption of heat (198 kJ), indicating an endothermic reaction. So, statement b is correct.
c. The statement "For the reaction 2SO2(g) + O2(g) 2SO3(g), H° = –198 kJ" is incorrect. The given equation is the reverse of the one stated in statement c. When a reaction is reversed, the sign of the enthalpy change (H°) is also reversed. So, the correct equation and enthalpy change for the reverse reaction would be 2SO3(g) 2SO2(g) + O2(g); H° = -198 kJ. Thus, statement c is incorrect.
d. The statement "The external pressure is 1 atm" does not provide enough information to determine its correctness in relation to the given equation. The equation only provides information about the enthalpy change (H°) and does not mention anything about pressure. Since the question asks for an incorrect statement, we cannot determine the correctness of statement d based on the given information.
e. The statement "For every mole of SO3(g) consumed, 99 kJ of heat at constant pressure is consumed as well" is incorrect. The given equation states that the enthalpy change (H°) is 198 kJ, not 99 kJ. Therefore, statement e is incorrect.
In conclusion, the incorrect statement concerning the thermochemical equation is statement c, which wrongly claims the enthalpy change for the reverse reaction.