For a physisorption process, which one of the following statements is NOT correct?a)There are van der Waals interactions between the adsorbate and the adsorbent.b)The process predominates at low temperaturec)The process cannot proceed beyond a monolayerd)The process is reversibleCorrect answer is option 'C'. Can you explain this answer?

Question

Answer

Physisorption Process

Physisorption is a type of adsorption in which the adsorbate molecules are held onto the surface of the adsorbent by weak van der Waals forces. It is a physical process that occurs at low temperatures and pressures. The following statements describe physisorption:

- Van der Waals interactions: There are weak attractive forces between the adsorbate and the adsorbent. These forces are van der Waals forces, which include London dispersion forces, dipole-dipole interactions, and hydrogen bonding. These forces are weaker than chemical bonds and do not involve the transfer of electrons.
- Low temperature: Physisorption predominates at low temperatures because the kinetic energy of the adsorbate molecules is low. At higher temperatures, the adsorbate molecules have more kinetic energy and are more likely to desorb from the surface.
- Monolayer: Physisorption cannot proceed beyond a monolayer because the adsorbate molecules are held onto the surface by weak forces. Once a monolayer is formed, the adsorbate molecules do not have enough energy to overcome the forces and form additional layers.
- Reversible: Physisorption is a reversible process because the adsorbate molecules are not chemically bonded to the adsorbent. The adsorbate molecules can be desorbed by increasing the temperature or decreasing the pressure.

Correct Statement

The statement that is NOT correct is: 'The process cannot proceed beyond a monolayer.' This statement is incorrect because physisorption can proceed beyond a monolayer if the pressure or temperature is increased. At higher pressures, the adsorbate molecules can overcome the weak forces and form additional layers. However, these layers are still held onto the surface by weak forces and can be desorbed by decreasing the pressure or increasing the temperature.

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