Adsorption of a gas on the surface of solid is generally accompanied by decrease entropy. Still it is a spontaneous process. Explain.

Explanation

Adsorption is accompanied by decrease in enthalpy as well as decrease in entropy of the system.
For a process to be spontaneous there is a decrease in Gibbs Energy.
`to` On the basis of equation `DeltaG= DeltaH-T DeltaS, DeltaG = -Ve`
If `DeltaH` has sufficiently high negative value and `TDeltaS `is positive.
`to` In an adsorption process which is spontaneous `DeltaH` becomes negative by combining about .
`to` As the adsorption proceeds ` DeltaH` becomes less and less negative ultimately, `DeltaH` becomes equal to `TDeltaS` and `DeltaG` becomes zero. At this state equilibrium is attained.