For a chemical reaction to be non-spontaneous at any temperature, which of the following conditions must be met?

Question

Quizplus · Accepted Answer

For a chemical reaction to be non-spontaneous at any temperature, the change in entropy (ΔS°) should be negative and the change in enthalpy (ΔH°) should be positive. This is because the Gibbs free energy equation is ΔG° = ΔH° - TΔS°, where T is the temperature in Kelvin. If both ΔS° and ΔH° have the same sign, then the value of ΔG° could be negative or positive depending on the temperature. However, if ΔS° is negative and ΔH° is positive, then ΔG° will always be positive, indicating a non-spontaneous reaction at all temperatures. Therefore, choice D (ΔS° < 0, ΔH° > 0) is the correct answer.

For a Chemical Reaction to Be Non-Spontaneous at Any Temperature