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प्रश्न
Give two important characteristics of physisorption.
What are the important characteristics of physical adsorption?
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उत्तर
- It is reversible; adsorbed gas can be easily removed by lowering pressure or increasing temperature.
- Heat of adsorption (enthalpy) is low, about 20-40 kJ/mol.
- The forces involved are weak van der Waals’ forces of attraction.
- It increases with an increase in pressure.
- It forms multilayers of adsorbate on the adsorbent surface.
- It is non-specific; almost any gas can be physically adsorbed.
- Adsorption decreases with an increase in temperature.
- Gases with higher critical temperatures (easily liquefiable) are adsorbed more readily.
- The process has almost zero activation energy and occurs rapidly.
Notes
Students should refer to the answer according to their questions.
संबंधित प्रश्न
For Freundlich isotherm a graph of log `"x"/"m"` is plotted against log p. The slope of the line and its y-axis intercept respectively corresponds to ____________.
Which of the following is incorrect for physisorption?
Which one of the following characteristics is associated with adsorption?
If x is the amount of adsorbate and m is the amount of adsorbent, which of the following relations is not related to adsorption process?
Differentiate physisorption and chemisorption.
In case of chemisorption, why adsorption first increases and then decreases with temperature?
Which will be adsorbed more readily on the surface of charcoal and why? NH3 or O2?
Heat of adsorption is greater for chemisorptions than physisorption. Why?
Why is desorption important for a substance to act as a good catalyst?
Which one of the is not a surfactant?
