Q. The following two reactions are known: Fe₂O₃(s) + 3CO(g) → 2Fe(s) + 3CO₂(g); ΔH = −26.8 kJ FeO(s) + CO(g) → Fe(s) + CO₂(g); ΔH = −16.5 kJ The value of ΔH for the following reaction Fe₂O₃(s) + CO(g) → 2FeO(s) + CO₂(g) is
A) +10.3 kJ
B) −43.3 kJ
C) −10.3 kJ
D) +6.2 kJ
Explanation
[Solution from source] Target = (first equation) − 2 × (second equation): Fe₂O₃ + 3CO − 2FeO − 2CO → 2Fe + 3CO₂ − 2Fe − 2CO₂, i.e. Fe₂O₃ + CO → 2FeO + CO₂. ΔH = −26.8 − 2(−16.5) = −26.8 + 33.0 = +6.2 kJ. −10.3 kJ comes from subtracting the second equation only once. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.