Heat of Adsorption Dependent on Coverage

Although the Langmuir theory of adsorption is used frequently for technical process development it is a crude approximation, as surface reconstruction frequently occurs. Adsorbed molecules change the structure of the surface layer and the catalytic properties of surface sites are not equal in the ability to bind chemisorbed molecules. The rate is dependent on spatial arrangement and the heat of adsorption depends on coverage (Figures 2.27, 2.28). 

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