Question

Which of these statements is true?

(a) All spontaneous reactions have a negative enthalpy change
(b) All spontaneous reactions have a positive entropy change
(c) All spontaneous reactions have a positive free-energy change
(d) All spontaneous reactions have a negative free-energy change
(e) All spontaneous reactions have a negative entropy change

Answer 1

Among the options listed, the correct statement is that all spontaneous reactions result in a negative free-energy change, reflecting the energy released during the process. So the correct option is d.

Step-by-step explanation:

The true statement among the options provided is:

(d) All spontaneous reactions have a negative free-energy change.

This is based on the principles of thermodynamics. The second law of thermodynamics states that the entropy of the universe increases in the course of spontaneous reactions. Nevertheless, a characteristic of spontaneous processes is that they release free energy, leading to a negative change in Gibbs free energy (ΔG). Therefore, not all spontaneous reactions have a negative enthalpy change (ΔH), nor do they always have a positive entropy change (ΔS), but they must result in a decrease in Gibbs free energy (negative free-energy change).

Answer 2

(d) All spontaneous reactions have a negative free-energy change

Step-by-step explanation:

All spontaneous reactions releases free energy which can be used later for the work to be done. A reaction with a negative value for ΔG releases free energy and is thus spontaneous