Question

For a spontaneous process at constant temperature and pressure, which of the following is true?

• A. \( \Delta G>0 \)
• B. \( \Delta H>0 \)
• C. \( \Delta G<0 \)
• D. \( \Delta S<0 \)

Hint:

For a spontaneous process at constant temperature and pressure, the correct thermodynamic condition is: \[ \Delta G = \Delta H - T\Delta S<0. \] This indicates the process proceeds with a decrease in free energy.

Answer 1

The Correct Option is C

Step 1: Use Gibbs free energy criteria.
For a process to be spontaneous at constant temperature and pressure, the change in Gibbs free energy must be negative, i.e., \[ \Delta G<0. \]
Step 2: Evaluate other options.
\( \Delta G>0 \): Implies non-spontaneous process.
\( \Delta H>0 \): Possible, but does not guarantee spontaneity.
\( \Delta S<0 \): May occur, but not a definitive condition for spontaneity.
\( \Delta G<0 \): This is the correct condition for spontaneity.