Question

Which of the following is true for spontaneous adsorption of $H_2$ gas without dissociation on the solid surface?

• A. Process is exothermic and $\Delta$ S $<0$
• B. Process is endothermic and $\Delta S>0$
• C. Process is exothermic and $\Delta S>0$
• D. Process is endothermic and $\Delta S<0$

Answer 1

The correct option is A Process is exothermic and $\Delta$ S $<0$

The following is true for spontaneous adsorption of $H_2$ gas without dissociation on a solid surface.
Process is exothermic and $\Delta$ S $<0$.

Note:
Adsorption of gases on the solid surface is generally exothermic because entropy decreases.
Adhering of gas molecules to the surface lowers randomness.

For adsorption process;
$\Delta G<0$, $\Delta H<0$ and $\Delta S<0$