Which one of the following enthalpy changes is always exothermic?
Correct answer: A. Enthalpy of combustion
- A. Enthalpy of combustion
- B. Enthalpy of formation
- C. Enthalpy of atomization
- D. Enthalpy of solution
Explanation
Combustion is an oxidation reaction that produces heat, and it is therefore always exothermic. Since these reactions are exothermic so the value for the enthalpy change (ΔH) is always negative
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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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