Chapter 22 - Topic 22B - Adsorption and desorption - Discussion Questions - Page 959: 22B.2

Langmuir isotherm is based on the following approximations: a) Adsorption stops after the formation of monolayer b) Surface is homogeneous c) There is no adsorption between the surface molecules BET isotherm is applicable if the monolayer can act as substrate for further adsorption. The postulates are: a) Surface is energetically homogeneous b) No interaction between the adsorbed molecules c) The adsorption energies of second and higher layers (E_{2}, E_{3}... E_{i}) are equal to the condensation energy of the adsorptive (E_{L}) i.e., E_{2}=E_{3}=.....=E_{i}=E_{L}

Langmuir isotherm is based on the following approximations: a) Adsorption stops after the formation of monolayer b) Surface is homogeneous c) There is no adsorption between the surface molecules BET isotherm is applicable if the monolayer can act as substrate for further adsorption. The postulates are: a) Surface is energetically homogeneous b) No interaction between the adsorbed molecules c) The adsorption energies of second and higher layers (E_{2}, E_{3}... E_{i}) are equal to the condensation energy of the adsorptive (E_{L}) i.e., E_{2}=E_{3}=.....=E_{i}=E_{L}