Which of the following statement is not correct?
Show Hint
Physical adsorption is characterized by weak forces of attraction.
- Adsorption energy for chemical adsorption is generally greater than that of physical adsorption
Physical adsorption is due to van der Waal forces
- Physical adsorption decreases at high temperature and low pressure
- Physical adsorption is irreversible
The Correct Option is D
Solution and Explanation
Adsorption is a process of deposition of molecules on the surface of another substance. It occurs in two ways:
- Physisorption
- Chemisorption
Physical adsorption is a reversible process. It occurs due to the non-covalent attraction between adsorbate and adsorbent. In Physisorption, the two molecules are held together by weak intermolecular forces i.e. van der Waal forces, hence it is reversible. With increase in temperature, physical adsorption of substances decreases. Since in physisorption, molecules are held together by weak forces of attraction, therefore its energy of adsorption is also low as compared to chemisorption. Hence, only the fourth statement is incorrect here.
In Chemisorption, the adsorbate and adsorbent are held together by strong covalent bonds, therefore this process is irreversible and requires high adsorption energy.
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Concepts Used:
Adsorption
Heinrich Kayser, the German physicist was the first to coin the term adsorption. Adsorption can be explained as a surface phenomenon where particles remain attached on the top of a material. Generally, it comprises the molecules, atoms, liquid, solid in a dissolved stage, even the ions of a gas that are attached to the surface. Much to our surprise, the consequence of surface energy i.e. adsorption is present in biological, physical, chemical, and natural systems and are used in many industrial applications.
