Comparison between Physisorption and Chemisorptions

Comparison between physisorption and chemisorptions

 

Physisorption

(Vander Waal's adsorption)

Chemisorption

(Langmuir adsorption)

Low heat of adsorption usually in range of 20-40 kJ/mol

High heat of adsorption in the range of 50-400 kJ/mol

Force of attraction are Vander Waal's forces.

Forces of attraction arechemical bond forces.

It is reversible

It is irreversible

It is usually takes place at low temperature and decreases with increasing temperature.

It takes place at high temperature.

It is related to the case of liquefication of the gas.

It is not related.

It forms multimolecular layers.

It forms monomolecular layers.

It does not require any activation energy.

It requires high activation energy.

High pressure is favourable. Decrease of pressure causesdesorption

High pressure is favourable. Decrease of pressure does not cause desorption.

It is not very specific.

It is highly specific.

 

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