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प्रश्न
Why is adsorption always exothermic?
उत्तर
ΔH is always negative because during adsorption, the surface energy decreases in the form of heat. Also, 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. So, 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
What is the difference between physisorption and chemisorption?
Give reasons for the following observations :
Powdered substances are more effective adsorbents.
Chromatography is based on the principle of ____________.
Which of the following is not a favourable condition for physical adsorption?
Physical adsorption of a gaseous species may change to chemical adsorption with ______.
In physisorption adsorbent does not show specificity for any particular gas because ______.
Why is it important to have clean surface in surface studies?
Which among the following is a false statement?
Which of the following statements is incorrect regarding physisorptions?
