Adsorption is a surface phenomenon where particles of a substance accumulate on the surface of a solid or liquid. Several factors influence the extent and efficiency of adsorption. Understanding these factors is essential for students preparing for competitive exams like JEE Main.
The extent of adsorption increases with an increase in surface area. Finely divided and porous materials provide more surface for adsorption to occur.
The ability of an adsorbent to attract and retain adsorbate particles is influenced by its composition and structural properties. For example, activated charcoal and silica gel are highly effective adsorbents.
The type and concentration of the substance being adsorbed (adsorbate) play a significant role. Compared to noble gases, substances like ammonia and hydrogen chloride are adsorbed more easily because of their stronger intermolecular attractions.
Adsorption is generally exothermic. Thus, physical adsorption decreases with an increase in temperature, while chemical adsorption may initially increase and then decrease due to bond formation.
In the case of gases, an increase in pressure generally increases the extent of adsorption, especially for physical adsorption, following Freundlich's adsorption isotherm.
Activation techniques such as heating, chemical treatment, or increasing surface roughness enhance the adsorbent’s efficiency by increasing its surface area or reactivity.
For solutions, the pH of the medium can affect the ionization of solutes and surface charges of the adsorbent, thus influencing adsorption behavior.
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