Simple decompositions on surfaces

In the case of the simple decomposition of a molecule on a surface, the process can be represented as a chemical reaction between the reactant A and a vacant site S on the surface. After adsorption, the molecule A may desorb unchanged or may decompose to products. The elementary steps are written 

If V is the rate of reaction per square metre of surface, then 

Let Cs be the total concentration of surface sites per square metre and let 6 be the fraction of these sites that are covered by A. Then = c O, and 0 (1 — 6) = the concentration of vacant sites on the surface. Then the rate of the reaction can be written 

The value of 6 is obtained by applying the steady-state condition to the rate of formation of AS  

5) must be considered in full, then it is convenient to invert it  

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