ï»¿ Define physical and chemical adsorption. from Chemistry Surface Chemistry Class 12 Nagaland Board

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Class 10 Class 12
Define physical and chemical adsorption.

If the adsorbate is held on the surface by weak Van der Waal’s forces, the process is called physical adsorption.

When an adsorbate is held on the surface of the adsorbent by chemical forces, it is called chemical adsorption.
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Why does physisorption decrease with the increase of temperature?

It is because physical adsorption involves weak forces of attraction between adsorbent and adsorbent molecules, generally of Vander Waal's type. These forces decrease rapidly with increase in temperature.
1705 Views

Why is the ester hydrolysis slow in the beginning and becomes faster after sometime?

Ester + water ---> Acid + Alcohal
The acid produced in the reaction acts as a catalysis and makes the reaction faster.

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Why are powdered substances more effective adsorbents than their crystalline forms?

Powderded substance are more effective adsorbent than their crystalline forms because when a substance is powdered its surface area increase and physisorption is directly proportional to the surface area of adsorbent,
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In Haber's process, hydrogen is obtained by reacting methane with steam in presence of NiO as catalyst. The process is known as steam reforming. Why is it necessary to remove CO when ammonia is obtained by Haber’s process?