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Enthalpy of chemisorption is as high asK...

Enthalpy of chemisorption is as high as_________`KJmol_(-1)` .

A

`400`

B

`240`

C

`80`

D

`40`

Text Solution

Verified by Experts

The correct Answer is:
A
Enthalpy of chemisorption is high `(80-240kJmol^(-1))` as it involves chemical bond formation.
in exceptional cases, chemisorption may be endothermic if less energy is released during adsorption than what is required to break bonds in adsorbate. Fopr example, `H_(2)` adsorbs endothermically on glass. However, the `DeltaS` in the process, `H_(2)(g)rarr2H` (glass), is sufficiently positive to overcome the small positive enthalpy change. Similarly highly hydrated solutes, when adsorbed on solid have positive `DeltaH` but are accompanied by large positive `DeltaS` due to release of water molecules on adsorption
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