Question

Adsorption of a gas on surface of solid is generally accompanied by a decrease in entropy, still it is a spontaneous process. Explain.

Answer 1

△S = -ve but △H is also negative due to attraction. △G = △H - T△S, △G can be negative if △H has sufficiently high negative value as - T△S is positive. So, in adsorption process, a combination of these two factors makes △G negative.