Equilibrium ad-atom concentration

At the Nemst potential Eq equilibrium is established for the ad-atom and metal ion concentration and one can define exchange rates of adsorption and desorption. 

From this equation one can derive an equilibrium surface coverage of the 

The standard potential of the metal is a constant (not dependent on the concentration). 

The constant expressions can be combined to an equihbrium constant of adsorption K. Neglecting differences between concentration and activity one obtains the Langmuir type adsorption isotherm of the ad-atoms 

The ad-atom concentration depends on the electrolyte concentration. The ad-atom concentration only becomes independent of the bulk concentration of the metal ions if there is a complete discharging of the ad-atom with A = 0. 

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