For the smelting of iron ore: 2Fe₂O₃ + 3C → 4Fe + 3CO₂, given ∆Hf° of Fe₂O₃ is -824.2 kJ/mol and ∆Hf° of CO₂ is -393.7 kJ/mol. The reaction is
Correct answer: A. Endothermic
- A. Endothermic
- B. Exothermic
- C. ∆H = 0
- D. None of the above
Explanation
The enthalpy of reaction is ΔH = ΣΔHf (products) - ΣΔHf (reactants). ΔH = [4(0) + 3(-393.7)] - [2(-824.2) + 3(0)] = -1181.1 + 1648.4 = +467.3 kJ. Since ΔH is positive, the reaction is endothermic.
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About Thermochemistry and Energetics of Chemical Reactions
Thermochemistry measures energy changes in chemical reactions and distinguishes exothermic from endothermic processes. Work covers systems, surroundings and state functions, internal energy, the first law of thermodynamics, enthalpy and Hess's law, including the sign conventions used when heat enters or leaves a system.
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