Chemistry - Thermodynamics - II Question with Solution | TestHub

Explain the question: Identify the correct thermodynamic assertion.

Concept: This question is based on the second law of thermodynamics and process definitions.

Solution:

At equilibrium, the Gibbs free energy change $\Delta G$ is zero, but the standard Gibbs free energy change $\Delta G^{\circ }$ depends on the equilibrium constant ($\Delta G^{\circ }=-RT\ln K_{eq}$) and is not necessarily zero.

Spontaneity requires $\Delta G=\Delta H-T\Delta S<0$; therefore, exothermic reactions ($\Delta H<0$) with a negative $\Delta S$ can be non-spontaneous at high temperatures.

The adiabatic relation $P{V}^{\gamma }=constant$ applies strictly to reversible processes of ideal gases. By definition, any adiabatic process (whether reversible or irreversible) has zero heat exchange with the surroundings ($q=0$).

Since the entropy change of the surroundings is defined as $\Delta S_{surrounding}=-q_{actual}/T_{surr}$, it must be zero for all adiabatic paths.

Final Answer: Option (D)