Question

The thermodynamic criterion for spontaneity of a process in a system under constant volume and temperature and in the absence of any work other than expansion work (if any) is

• A. change in entropy is positive
• B. change in enthalpy is negative
• C. change in Helmholtz free energy is negative
• D. change in Gibbs free energy is negative

Hint:

For a process to be spontaneous, the change in Gibbs free energy must be negative (\( \Delta G<0 \)).

Answer 1

The Correct Option is C

Step 1: Understanding spontaneity.
The spontaneity of a process is determined by the change in Gibbs free energy \( \Delta G \). For a process to be spontaneous, \( \Delta G \) must be negative.
Step 2: Conclusion.
Thus, the correct criterion for spontaneity is that the change in Gibbs free energy is negative, which corresponds to option (D).
Step 3: Conclusion.
The correct answer is (D) change in Gibbs free energy is negative.