Chemistry - Surface Chemistry Question with Solution | TestHub

(a) In the process of adsorption, a bond is formed between adsorbate and adsorbent, hence always exothermic. (b) Physisorption require very low activation energy while chemisorption require high activation energy. Therefore a physisorption may transform into chemisorption but only at high temperature. (c) It is wrong statement as at higher temperature, physically adsorbed substance starts desorbing. (d) In physical adsorption, van der Waals' force hold the adsorbate and adsorbent together which is a weak electrostatic attraction. In chemisorption, strong chemical bond binds the adsorbate to the adsorbent. Therefore, chemisorption is more exothermic than physical adsorption.