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Surface Chemistry — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistrySurface Chemistry3 Marks
Question
Give three points of difference between physisorption and chemisorption.
✓

Answer

S. No.
Physisorption
Chemisorption
1.
Happens due to van der Waal forces.
Caused by a chemical bond.
2.
It's not specific in nature and reversible in nature.
Highly specific in nature and irreversible.
3.
It depends on the nature of the gas. More liquefiable gas is adsorbed easily.
Depend on the nature of the gas. those gases can react with the adsorbent show chemisorption.
4.
Enthalpy of adsorption is low around 20-40kJ/ mol.
Enthalpy if adsorption is high around 80-240kJ/ mol.
5.
Low temperature required.
High temperature is required.
6.
It depends on the surface area. Higher the area high in the process rate.
High activation energy is needed sometimes.
7.
Results in multimolecular layers on the adsorbent surface.
Result is unimolecular.

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