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प्रश्न
Why is adsorption always exothermic?
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उत्तर
ΔH is always negative because during adsorption, the surface energy decreases in the form of heat. Furthermore, ΔS is negative because when a gas is adsorbed on a solid surface, its movement is restricted; this leads to a decrease in the entropy of the gas. Now, for a process to be spontaneous, ΔG should be negative.
∴ ΔG = ΔH − TΔS
Because ΔS is negative, TΔS becomes positive. Therefore, ΔH has to be highly negative for the spontaneous process to make ΔG negative. Hence, adsorption is always exothermic.
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संबंधित प्रश्न
Write the differences between physisorption and chemisorption with respect to the following:
(i) Specificity
(ii) Temperature dependence
(iii) Reversibility and
(iv) Enthalpy change
Distinguish between the meaning of the terms adsorption and absorption. Give one example of.
Give reason why a finely divided substance is more effective as an adsorbent.
Write one similarity between Physisorption and Chemisorption
Chromatography is based on the principle of ____________.
Why is chemisorption referred to as activated adsorption?
Why do physisorption and chemisorption behave differently with rise in temperature?
What is the role of diffusion in heterogenous catalysis?
What is the role of adsorption in heterogenous catalysis?
Assertion A : Activated charcoal adsorbs SO2 more efficiently than CH4.
Reason R : Gases with lower critical temperatures are readily adsorbed by activated charcoal.
In light of the above statements, choose the correct answer from the options given below.
