Given the reactions below, compute ΔH° for the reaction: (ΔH's are all given in kJ)
2 MnO₂(s) + CO(g) → Mn₂O₃(s) + CO₂(g)
Reaction ΔH°rxn
MnO₂(s) + CO(g) → MnO(s) + CO₂(g) - 150.6
Mn₃O₄(s) + CO(g) → 3 MnO(s) + CO₂(g) - 54.4
3 Mn₂O₃(s) + CO(g) → 2 Mn₃O₄(s) + CO₂(g) - 142.3

Question

Quizplus · Accepted Answer

To find ΔH°rxn for the given reaction, we need to manipulate the given reactions in order to isolate the desired products and reactants. First, we reverse the third reaction so that we have Mn₂O₃(s) and Mn₃O₄(s) as products: 2 Mn₃O₄(s) + CO₂(g) → 3 MnO(s) + CO(g) Next, we use the first two reactions to cancel out the MnO(s) and CO(g) on the right side of the above equation: MnO₂(s) + CO(g) → MnO(s) + CO₂(g) (multiplied by 3 to match coefficients) 3 Mn₃O₄(s) + CO(g) → 2 Mn₃O₄(s) + CO₂(g) When we add these two reactions together, we get the desired reaction: 2 MnO₂(s) + CO(g) → Mn₃O₄(s) + CO₂(g) To compute the ΔH°rxn for this reaction, we need to add up the ΔH° values for the reactions we used (multiplied by appropriate coefficients): ΔH°rxn = (2 × (-150.6)) + (-54.4) + (-2 × (-142.3)) = -217.1 kJ Therefore, the answer is C.

Given the Reactions Below, Compute ΔH° for the Reaction: (ΔH's