| Physical adsorption | Chemical adsorption |
| Weak van der Waals forces are present between adsorbate and adsorbent. | Strong chemical (covalent) bonds are formed between adsorbate and adsorbent. |
| It has low heat of adsorption (20 to 40 kJ/mol). | It has high heat of adsorption (40 to 200 kJ/mol). |
| Multilayers of adsorbed particles are formed. | Monolayer of adsorbed particles is formed. |
| It is not specific in nature. | It is specific in nature. |