Question

Which of the following conditions indicates the reaction is spontaneous?

• A. \( \Delta S<0, \Delta H>0, \Delta G>0 \) at all temperature
• B. \( \Delta S<0, \Delta H>0, \Delta G>0 \) at low temperature
• C. \( \Delta S>0, \Delta H<0, \Delta G<0 \) at all temperature
• D. \( \Delta S<0, \Delta H>0, \Delta G>0 \) at high temperature

Hint:

A reaction is spontaneous if \( \Delta G<0 \). Ensure that both entropy increases (\( \Delta S>0 \)) and enthalpy decreases (\( \Delta H<0 \)) for spontaneity.

Answer 1

The Correct Option is C

Step 1: Understanding spontaneity in reactions.
A reaction is spontaneous when the Gibbs free energy \( \Delta G \) is negative, which occurs when both \( \Delta S \) (entropy) is positive and \( \Delta H \) (enthalpy) is negative.
Step 2: Analyzing the options.
(A) \( \Delta S<0, \Delta H>0, \Delta G>0 \): Incorrect — this represents a non-spontaneous reaction.
(B) \( \Delta S<0, \Delta H>0, \Delta G>0 \): Incorrect, this condition indicates the reaction is non-spontaneous at low temperatures.
(C) \( \Delta S>0, \Delta H<0, \Delta G<0 \): Correct — this condition ensures the reaction is spontaneous at all temperatures.
(D) \( \Delta S<0, \Delta H>0, \Delta G>0 \): Incorrect, this condition represents a non-spontaneous reaction.
Step 3: Conclusion.
The correct answer is (C) \( \Delta S>0, \Delta H<0, \Delta G<0 \) at all temperature.