Short Answer TypeWrite three distinct features of chemisorptions which are not found in physisorptions.
Chemisorption is a kind of adsorption which involves a chemical reaction between the surface and the adsorbate.
Physisorption, also called physical adsorption, is a process in which the electronic structure of the atom or molecule is barely perturbed upon adsorption.
|
S. No. |
Point of difference |
Physiosorption |
Chemisorption |
|
(i) |
Specificity |
This is not specific in nature. |
This is highly specific in nature. |
|
(ii) |
Temperature dependence |
Low temperature is favourable for physiosorption. It decreases with increase in temperature. |
High temperature is favourable for chemisorption. It increases with the increase in temperature. |
|
(iii) |
Reversibility |
This is reversible in nature. |
This is irreversible in nature. |
|
(iv) |
Enthalpy change |
Enthalpy of adsorption is low. |
Enthalpy of adsorption is high. |
(i) Differentiate between adsorbtion and absorption.
(ii)Out of MgCl2 and AlCl3, which one is more effective in causing coagulation of negatively charged sol and why?
(iii)Out of sulphur sol and proteins, which one form multimolecular colloids?
Define the following terms:
i)Lyophilic colloid
ii) Zeta potential
iii) Associated colloids
Classify colloids where the dispersion medium is water. State their characteristics and write an example of each of these classes.
OR
Explain what is observed when
(i) An electric current is passed through a sol
(ii) A beam of light is passed through a sol
(iii) An electrolyte (say NaCl) is added to ferric hydroxide solWrite one difference in each of the following :
Homogeneous catalysis and Heterogeneous catalysis
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