Question

Which one of the following characteristics is associated with adsorption?

Options

• ΔG and ΔH are negative but ΔS is positive.

• ΔG and ∆S are negative but ∆H is positive.

• ∆G is negative but ∆H and ∆S are positive.

• ∆G, ∆H and ∆S all are negative.

Answer 1

∆G, ∆H and ∆S all are negative.

Explanation:

Adsorption leads to a decrease in randomness (entropy); i.e., ∆S < 0 for the adsorption to occur, ∆G should be negative. We know that ∆G = ∆H − T∆S If ∆S is negative, then T∆S becomes positive. It means that ∆G will become negative only when ∆H is negative and ∆H > T∆S.