What I want to know is about the adsorption enthalpy change by the change of surface coverage and the adsorption rate. In general situations, adsorption would be exothermic. So in the Gibbs free energy equation ${\displaystyle \Delta G^{\circ }=\Delta H^{\circ }-T\Delta S^{\circ }}$, adsorption usually fixes molecules on the surface of the adsorbent so $\Delta S^{\circ}$ is negative and therefore, the higher absolute value of negative $\Delta H^{\circ }$ would cause the adsorption to be more spontaneous. Can this change of spontaneity affect the rate of adsorption if the pressure and temperature are same? If not, what causes the adsorption rate to decrease when surface coverage increases in the same temperature, pressure and concentration?

  • 1
    $\begingroup$ I think you mean $\Delta S^ \circ$ is negative because entropy $S^\circ$ itself is always positive. Are you? $\endgroup$ May 27, 2023 at 17:42
  • $\begingroup$ Yes. I think I made a mistake there $\endgroup$
    – nohseo
    May 27, 2023 at 23:41


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Browse other questions tagged or ask your own question.