GUJARAT SET 2023
Which of the following is true regarding adsorption?
- (A) ΔG < 0, ΔS > 0, ΔH < 0
- (B) ΔG > 0, ΔS < 0, ΔH < 0
- (C) ΔG < 0, ΔS > 0, ΔH > 0
- (D) ΔG < 0, ΔS < 0, ΔH < 0
Correct Option: (D) ΔG < 0, ΔS < 0, ΔH < 0
Explanation:
- ΔG < 0 (Spontaneous): Adsorption is a spontaneous process, meaning the Gibbs free energy must decrease.
- ΔS < 0 (Entropy): When gas or liquid molecules are adsorbed onto a solid surface, their freedom of movement is restricted, leading to a decrease in randomness (entropy).
- ΔH < 0 (Exothermic): For the process to be spontaneous despite a negative entropy change, the enthalpy change must be negative (exothermic) to satisfy the relation ΔG = ΔH - TΔS.