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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