In an exothermic reaction (reversible), which of the following has a positive value?
Correct answer: C. Gibb's free energy
- A. Enthalpy
- B. Entropy
- C. Gibb's free energy
- D. None of these options are correct
Explanation
In an exothermic reversible reaction, the change in Gibbs free energy (ΔG) can have a positive value at lower temperatures due to the balance between the negative change in enthalpy (ΔH) and the positive change in entropy (ΔS). This positive ΔG indicates that the reaction is nonspontaneous under those conditions. The sign of ΔG depends on the interplay between ΔH, ΔS, and temperature, and it determines whether a reaction is spontaneous or nonspontaneous.
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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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