Adsorption Entropy on Heterogeneous Surfaces with Surface Diffusion

2 Adsorption Entropy on Heterogeneous Surfaces with Surface Diffusion 

Pursuing more realistic formulae for calculation of the adsorption enthalpy, we will incorporate the mixed adsorption entropy S /R. From Eqs. 5.42 and 5.70 it follows that the entropy change for the each partial adsorption isotherm is  

Let the combined quantities under the logarithms in the above formula be B c and fimb, respectively. Then the equilibrium constant, cf. Eq. 5.72, can be evaluated from  

It requires numerical integration. Another possibility is to suppose that the barrier is a constant fraction bb of the desorption energy, Ej = E, E(p then no condition is imposed on m- The resulting formula, analogous to 5.77, is equally cumbersome. 

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