Question

For a particular reversible reaction at temperature T, Δ H and Δ S were found to be both positive. If Tₑ is the temperature at equilibrium, the reaction would be spontaneous when:

• A. \(T_e > T\)
• B. \(T > T_e\)
• C. \(T_e\) is 5 times \(T\)
• D. T = Tₑ

Hint:

For Δ H>0 and Δ S>0, spontaneity requires high temperature.

Answer 1

The Correct Option is B

Step 1: Gibbs free energy: Δ G=Δ H - TΔ S
Step 2: At equilibrium: Δ G=0 ⟹ Tₑ=(Δ H)/(Δ S)
Step 3: Reaction is spontaneous when: Δ G<0 ⟹ T>Tₑ