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Why heat of chemisorption is more than h...

Why heat of chemisorption is more than heat of physisorption?

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In chemisorption, molecules of adsorbate are held to the surface of the adsorbent by chemical bonds. On the other hand, in physisorption, adsorbate molecules are held by the weak van der Waals forces. Hence, more energy is released during chemisorption as compared to physisorption.
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Which of the following statements is not true? a. Both physisorption and chemisorption are exothermic. b. Physisorption occurs with increase of free energy. c. Physisorption requires low activation energy but chemisorption requires high activation energy. d. The magnitude of chemisorption increases and that of physisorption decreases with rise in temperature.

The correct statement(s) pertaining to the adsorption of a gas on a solid surface is(are) (i) adsorption is always exothermic (ii) physisorption may transform into chemsisorption transform into chemisorption at high temperature (iii) physisorption increases with increasing temperature but chemisorption decreases with increasing temperature . (iv) chemisorption is more exothermic than physisorption , however it is very slow due to higher energy of activation.

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Write three distinct features of chemisorptions which are not found in physisorptions.

Write three distinctive features of chemisorption which are not found in physisorption.

Why actinoid contraction is more than lanthanoid contraction

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ICSE-SURFACE CHEMISTRY -EXERCISE (PART-II ( DESCRIPTIVE QUESTIONS )) (VERY SHORT ANSWER QUESTIONS)
  1. Why all adsorptions are exothermic in nature ?

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  2. Why heat of chemisorption is more than heat of physisorption?

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  3. What is meant by positive and negative adsorptions?

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  4. Why activated charcoal is a better adsorbent than ordinary charcoal ?

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  5. How will you prove the selective nature of adsorption ?

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  6. How is adsorption of a gas related to its critical temperature?

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  7. Out of the following gases which will be adsorbed more readily on the ...

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  8. Why is ferric chloride preferred over potassium chloride in case of a ...

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  9. What happens when a colloidal sol of Fe(OH)3 is mixed with that of As2...

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  10. What happens when persistent dialysis of a colloidal solution is carri...

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  11. What happens when a beam of light is passed through As2S3 sol?

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  12. KCl is added to Fe(OH)3 sol?

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  13. What is the main cause of charge on a colloidal solution?

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  14. How are gold number and protective power of colloid related?

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  15. What is demulsification ?

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  16. Give four uses of emulsions.

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  17. What are micelles ? Give an example of a micellers system.

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  18. How does soap help in washing clothes?

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  19. What modification can you suggest in the Hardy-Schulze law?

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  20. Why is it essential to wash the precipitate with water before estimati...

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