Distinguish between Freundlich adsorption isotherm and Langmuir adsorption isotherm also by plotting graphs?

Adsorption is defined as Adhesion of atoms, ions, bimolecules or molecules of gas, liquid or dissolved solids to a surface is called adsorption.It can be explainedby defining the two terms adsorbent and adsorbate.

Adsorbent : The substance on whose surface the adsorption occurs is known as adsorben.

Adsorbate : The substance whose molecules get adsorbed on the surface of the adsorbent ( i.e. solid or liquid ) is known as adsorbate.

Adsorption process is usually studied through graphs known as adsorption isotherm. It is the amount of adsorbate on the adsorbent as a function if its pressure or concentration at constant temperature.

Difference between Langmuir isotherm and  Freundlich isotherm

Freundlich isothermLangmuir isotherm

 It tells about the quantity of gas adsorbed by unit mass of solid adsorbent with pressure.It is represented by formula

Freundlich Adsorption equation

It tells about the number of active sites of the surface undergoing adsorption and pressure.

Langmuir Equation


Freundlich isotherm provides information about heterogeneity of adsorption sites

Langmuir isotherm provides information about homogeneity of adsorption sites
It is failed to explain adsorption at high pressure.It is also failed to explain adsorption at high pressure.
It does not tell any thing about adsorption and desorption. His theory is totaly based on adsorption and desorption equilibrium.




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