Given C(s) + O₂(g) → CO₂(g), ΔH = −393.5 kJ mol⁻¹ and CO(g) + ½O₂(g) → CO₂(g), ΔH = −283.0 kJ mol⁻¹, what is ΔH for C(s) + ½O₂(g) → CO(g)?
Correct answer B. −110.5 kJ mol⁻¹
Explanation
Reverse the second equation (+283.0) and add it to the first: ΔH = −393.5 + 283.0 = −110.5 kJ mol⁻¹. Adding both as given wrongly gives −676.5.
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