Chemisorption

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Chemisorption is a type of adsorption whereby a molecule adheres to a surface through the formation of a chemical bond, as opposed to physisorption. It is characterised by:

High temperatures.
Type of interaction: strong; covalent bond between adsorbate and surface.
High enthalpy: $\Delta H \approx 400 KJ/mol$
Adsorption takes place only in a monolayer.
High activation energy

[edit] Uses

The main way in which most chemists utilise the effect of chemisorption is in catalysed reactions. The process of chemisorption is actually pivotal to the role of heterogeneous catalysis where the catalyst is in a solid phase - particularly transition metal catalysts. In many cases the chemical reagents will both bind to the catalytic surface. The chemical bonds then form and draw electrons away from the chemisorption bonds. The molecule then desorbs and is free to leave the surface.