Final answer:
A process that is exothermic and has a decrease in entropy may or may not be spontaneous, depending on the change in Gibbs free energy (∆G).
Step-by-step explanation:
A process that is exothermic and has a decrease in entropy may or may not be spontaneous, depending on the change in Gibbs free energy (∆G).
According to the second law of thermodynamics, a spontaneous process is one that results in an increase in total entropy of a system and its surroundings. The change in Gibbs free energy (∆G) is related to enthalpy change (∆H) and entropy change (∆S) through the equation ∆G = ∆H - T∆S, where T is the temperature in Kelvin.
If the ∆G value is negative, the process is spontaneous. If the ∆G value is positive, the process is non-spontaneous. Therefore, the change in Gibbs free energy (∆G) is the determining factor for whether an exothermic process with a decrease in entropy is spontaneous or not.