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KCET · Chemistry · Surface Chemistry

Which of the following statements is incorrect w.r.t. Physisorption ?

  1. A The forces involved are van der Waal's forces,
  2. B More easily liquifiable gases are adsorbed easily.
  3. C Under high pressure it results into Multi-molecular layer on adsorbent surface
  4. D \( \Delta H_{\text {adsorption }} \) is low and \( +V e \)
Verified Solution

Answer & Solution

Correct Answer

(D) \( \Delta H_{\text {adsorption }} \) is low and \( +V e \)

Step-by-step Solution

Detailed explanation

Physisorption is an exothermic process but, its enthalpy ofadsorption is low, because attractive forces between
adsorbent and the adsorbate molecules are weak (i.e., van der Waals forces) and therefore, molar enthalpy ( \( \Delta \mathrm{H} \) ) of
adsorption is low and is of the order of \( 20-40 \mathrm{~kJ} \mathrm{~mol}^{-1} \). Maximum of gas is adsorbed when pressure is increased as
the volume of gas decreases. The gases which are easily liquefied are adsorbed readily, because van der Waals forces
are stronger near the critical temperature.