The<unk>  or<unk>  isotherm or<unk>  adsorption<unk>  relates the coverage or adsorption of molecules on a solid surface to gas pressure or concentration of a medium above the solid surface at a fixed temperature. The<unk>  was developed by Irving<unk>  in 1916.  The<unk>  is stated as:
θ or theta is the percentage coverage of the surface, P is the gas pressure or concentration, α alpha is a constant.
The constant α is the<unk>  adsorption constant and increases with an increase in the strength of adsorption and with a decrease in temperature. The<unk>  is derived starting from the equilibrium between empty surface sites, particles and filled particle sites
equilibrium between empty surface sites S* and particles P and filled surface sites SP
Because the fraction of filled surface sites is equal to θ and the fraction of unfilled sites equal to 1-θ and because P is proportional to the gas pressure or concentration the<unk>  can be rewritten to
Other<unk> s relating to adsorption exist such as the Temkin<unk>  or the Freundlich<unk> . The<unk>  (as a relationship between the concentration of a compound adsorbing to binding sites and the fractional occupancy of the binding sites) is equivalent to the Hill<unk> .
Langmuir equation
Arrhenius equation
Equation of state
Freundlich equation
Franck-Condon principle
Starling equation
Quantum yield
Gibbs free energy