Question

Adsorption of gases on solid surface is generally exothermic because during adsorption

Options

• A)

• entropy decreases

• B)

enthalpy increases

• C)

  entropy increases

• D)

  free energy increases

.

Answer 1

Adsorption of gases on solid surface generally exothermic. According to this satement the ΔH = -ve

Condition for spontaneous process
ΔG = - ve .....1

During adsorption
ΔS = -ve i.e less than zero ...2

Formula used :
ΔG= ΔH-TΔS

ΔS = - ve then -TΔS must be positive according to above equation. Now, reaction can only spontaneous or ΔG = - ve if ΔH = -ve. i.e. Hence, Adsorption of gases on solid surface generally exothermic because of decreases ion entropy

Answer : A)