Question

What is the enthalpy of adsorption?

Answer 1

Let us understand that adsorption is commonly referred to as a surface phenomenon in which particles adhere to the top layer of a material. It usually involves the molecules, atoms, or even ions of a dissolved gas, liquid, or solid adhered to the surface. And the measurement of energy or heat in a thermodynamic system is enthalpy. And the enthalpy of adsorption refers to the measure of heat released during adsorption.

Complete answer:
Enthalpy of adsorption is the heat emitted or consumed during the adsorption process in thermodynamic terms. In the vast majority of cases, adsorption is an exothermic mechanism, making it thermodynamically advantageous.
Molar Heat or Molar Enthalpy of Adsorption is the quantity of heat released when a $1$ mole of an adsorbate is adsorbed on the surface of an adsorbent.
The enthalpy or heat of adsorption can be mathematically described using the Van't Hoff equation.
Note: It must be noted that adsorption causes London Dispersion Forces, a form of Van der Waals Force that happens between molecules. The force functions in the same way that magnetic forces do between planets. Chemisorption has a higher enthalpy of adsorption because it necessitates the formation of chemical bonds. Absorption requires two components known as adsorbent and absorbent.

Note:
We need to know that adsorption is generally known to be of two types, physical adsorption and chemical adsorption. Physical adsorption is due to weak van der waal forces between adsorbate and adsorbent. On the other hand, chemical adsorption is caused by strong chemical bonding between adsorbate and adsorbent.