Use the given standard enthalpies of formation to determine the heat of reaction of the following reaction:2 LiOH(s) + CO₂(g) → Li₂CO₃(s) + H₂O(l)ΔH°f LiOH(s) = -487 kJ/moleΔH°f Li₂CO₃(s) = -1216 kJ/moleΔH°f H₂O(l) = -286 kJ/moleΔH°f CO₂(g) = -394 kJ/mole
Correct answer: D. -134 kJ
- A. -198.6 kJ
- B. +198.6 kJ
- C. +133.5 kJ
- D. -134 kJ
Explanation
To find the heat of reaction (ΔH°), apply the formula: ΔH° = ΣΔH°f (products) - ΣΔH°f (reactants). For this reaction: ΔH° = [(-1216 kJ/mole) + (-286 kJ/mole)] - [2*(-487 kJ/mole) + (-394 kJ/mole)]. This simplifies to: ΔH° = (-1502 kJ) - (-1668 kJ) = -134 kJ. Therefore, the correct answer is Option D: -134 kJ. Other options are incorrect due to errors in sign or magnitude, not representing the exothermic nature of the reaction.
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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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