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: Apply Gibbs Free Energy Criterion.
A process is spontaneous at constant temperature and pressure if the change in Gibbs free energy is negative, represented as \[ \Delta G<0. \]
Step 2: Analyze Alternative Conditions.
\( \Delta G>0 \): Indicates a non-spontaneous process.
\( \Delta H>0 \): While possible, this condition alone does not ensure spontaneity.
\( \Delta S<0 \): Such an event might occur, but it is not a definitive requirement for spontaneity.
\( \Delta G<0 \): This is the definitive condition for a spontaneous process.