Write the differences between physisorption and chemisorption with respect to the following: (i) Specificity (ii) Temperature dependence (iii) Reversibility and (iv) Enthalpy change

Physisorption Chemisorption

1. Physisorption is non- specific in nature due to Van der Waal's forces
2. Chemisorption is highly specific in nature due chemical bond between adsorbate and adsorbent
3. On increasing temperature chemisorption increases.
4. Physisorption decreases with temperature
   3.Physisorption is reversible in nature
5. Chemisorption is irreversible in nature
6. In case of physisorption enthalpy change is small. For example, 20-40 kJ mol⁻¹ (approx)
7. In case of chemisorption enthalpy change is high. For example, 40-400 kJ mol⁻¹ (approx)