Difference between Adsorption and Absorption
| Adsorption | Absorption |
| It is a surface phenomenon. | It concerns with the whole mass of the absorbent. |
| In it, the substance is only retained on the surface and does not go into the bulk or interior of the solid or liquid. | It implies that a substance is uniformly distributed, through the body of the solid or liquid. |
| In it the concentration of the adsorbed molecules is always greater at the free phase. | In it the concentration is low.
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| It is rapid in the beginning and slows down near the equilibrium. | It occurs at the uniform rate. |
Examples : (i) Water vapours adsorbed by silica gel. (ii) NH3 is adsorbed by charcoal.
| Examples : (i) Water vapours absorbed by anhydrous CaCl2 (ii) NH3 is absorbed in water forming NH4OH |