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Physical Adsorption is one type of Adsorption. Physical adsorption is a very important concept of chemistry and questions often from this Concept come in not just only in board examinations but also come in competitive exams like UPSC examinations. Adsorption can be defined as the phenomenon associated with surface chemistry. Adsorption is usually the sticking of a particle to a surface. This sticking of particles can be permanent or could be removed through a chemical process like heating the surface. The extent of difficulty in leaving the surface by the particles will denote the nature of adsorption, whether it is chemical Adsorption or physical adsorption. Physical adsorption is a type of Adsorption that takes place when the substance comes in contact with a liquid or solid surface. The other name for physical adsorption is physisorption. In the following parts, adsorption will be defined more clearly. Two types of Adsorption are physisorption and chemisorption.
Define Adsorption
Adsorption can be defined as a Concept of Surface Chemistry that is focused on the fact that the solid surface always tends to retain and attract the molecules of a phase when it comes in contact with them. These molecules stick on the outer parts of the surface and they don’t at the inner parts or in bulk. The molecules of the species are gathered at the surface on the outer parts and they never go into the bulk of the surface. This process is known as Adsorption. Generally, two types of adsorption take place one is physisorption or Physical Adsorption, and the other one is chemical Adsorption or chemisorption. They are as follows:-
- Physisorption or Physical Adsorption – If the gathering of gas on a solid surface takes place based on weak van der Waals forces, then this type of adsorption will be considered physisorption or Physical Adsorption. In simple words, physisorption takes place when a substance naturally comes in contact with a liquid or solid surface.
- Chemical Adsorption or chemisorption – So whenever a gas or atom is reserved to the solid surface due to any kind of chemical bond, this phenomenon is considered to be chemisorption or chemical Adsorption. This process includes high energy activation therefore it is also termed activated adsorption.
Difference Between Physisorption and Chemisorption
In the previous parts, the definition of physisorption and chemisorption was shown in simple words very briefly. Now let’s discuss points of differentiation between physisorption and chemisorption.
Physisorption or Physical Adsorption | Chemisorption or Chemical Adsorption |
Physisorption takes place with the help of weak van der Waals forces. | It takes place due to some kind of chemical bond. |
Physical adsorption is not specific. | Chemical Adsorption is highly specific. |
This process is of reversible tendency. | Chemisorption is irreversible. |
It usually relies on the tendency of gas. The more liquefiable gas there is, the more easily it will get adsorbed. | This also depends on the nature of the gas, but gases that will affect the adsorbent will show chemisorption more clearly. |
Physisorption always requires low temperatures. Usually, it decreases as the temperature increases. | On the other hand, chemisorption requires High temperature, it increases as the temperature increases. |
New compounds are not formed in the process of physical adsorption. | On the other side, new compounds are formed in the chemical Adsorption process. |
One example of physisorption can be multilayer adsorption. | One example of chemisorption can be monolayer adsorption. |
Conclusion
This article was a complete brief on the understanding of physical adsorption. Physisorption and Chemisorption are two types of Adsorptions. This article has briefly shown the difference between physisorption and chemisorption processes. Adsorption can be defined as a Concept of surface chemistry that works on the fact that a solid surface has the nature to attract or retain the molecules of phase when it comes in contact with the Surface. Physical adsorption or physisorption is a very important concept of chemistry. It is not only important for board examinations but questions often from this Concept come in competitive exams like UPSC examinations.
