JEE Main 2023 — Surface Chemistry Question with Solution

Adsorption is the process of a substance (adsorbate) being attracted to a surface (adsorbent). The enthalpy change for adsorption, $\mathrm{\Delta }{\mathrm{H}}_{\mathrm{ads}}$, is negative because the adsorbent and adsorbate are brought closer together, which releases energy.

Micelle formation is the process of surfactant molecules clustering together in water to form micelles. The micelles have a hydrophobic (water-repelling) core and a hydrophilic (water-loving) surface. The enthalpy change for micelle formation, $\mathrm{\Delta }{\mathrm{H}}_{\mathrm{mic}}$, is positive because the surfactant molecules are moving from a state of high entropy (dispersed in water) to a state of low entropy (clustered together).

Here is a table summarizing the enthalpy changes for adsorption and micelle formation: