Which of the following processes is considered energetically unfavorable?

• A. A reaction with a positive Gibbs free energy change (ΔG > 0)
• B. A reaction that releases heat to the surroundings
• C. A reaction with a negative Gibbs free energy change (ΔG < 0)
• D. A reaction that increases the entropy of the system

Answer: (A)

Verified step by step guidance

1. Understand that Gibbs free energy (ΔG) is a thermodynamic potential that can predict the direction of a chemical reaction. It combines enthalpy (ΔH), entropy (ΔS), and temperature (T) in the equation: ΔG = ΔH - TΔS.
2. Recognize that a reaction is considered energetically favorable or spontaneous if the Gibbs free energy change (ΔG) is negative (ΔG < 0). This means the reaction can occur without the input of additional energy.
3. Identify that a reaction with a positive Gibbs free energy change (ΔG > 0) is energetically unfavorable or non-spontaneous, meaning it requires energy input to proceed.
4. Recall that a reaction that releases heat to the surroundings is exothermic, which typically contributes to a negative ΔH, potentially making ΔG negative if entropy change (ΔS) is not unfavorable.
5. Understand that a reaction that increases the entropy of the system (positive ΔS) can contribute to a negative ΔG, especially at higher temperatures, making the reaction more likely to be spontaneous.