What is the change in enthalpy when 9.00 mol of sulfur trioxide decomposes to sulfur dioxide and oxygen gas?
2SO₂(g) + O₂(g) → 2SO₃(g) ; ΔH° = 198 kJ

Question

Quizplus · Accepted Answer

The balanced chemical equation shows that for the decomposition of 2 mol of SO3, the change in enthalpy (ΔH°) is 198 kJ. Therefore, for the decomposition of 9 mol of SO3, the ΔH° would be (198 kJ/2 mol) x 9 mol = 891 kJ. However, since the reaction is a decomposition, the enthalpy change would be negative (exothermic) and thus the answer is -891 kJ or choice C.

What Is the Change in Enthalpy When 9