Question

The enthalpy change for the adsorption process and micelle for mation respectively are

• A. \(∆H_{ads} < 0\ and\ ∆H_{mic} < 0\)
• B. \(∆H_{ads} > 0\ and\ ∆H_{mic} < 0\)
• C. \(∆H_{ads} < 0\ and\ ∆H_{mic} > 0\)
• D. \(∆H_{ads} > 0\ and\ ∆H_{mic} > 0\)

Hint:

Adsorption is exothermic (releases heat); micelle formation is endothermic (ab sorbs heat)

Answer 1

The Correct Option is C

The question involves understanding the enthalpy changes associated with two processes: adsorption and micelle formation. Let's examine each process: 

1. Adsorption:

Adsorption is the process where molecules from a gas or liquid phase accumulate on a solid or liquid surface. This process generally involves the release of energy, making it an exothermic process. Thus, the enthalpy change \( ∆H \) for adsorption is less than zero (\( ∆H_{ads} < 0 \)).

1. Micelle Formation:

Micelle formation occurs when surfactant molecules in solution organize into spherical structures at concentrations above the critical micelle concentration (CMC). Maintaining the micelles requires energy to be absorbed to overcome the repulsive forces among the hydrophilic heads of the surfactants. Consequently, micelle formation is an endothermic process, with the enthalpy change \( ∆H \) being greater than zero (\( ∆H_{mic} > 0 \)).

Given these explanations, we can conclude that for the adsorption and micelle formation processes:

• \( ∆H_{ads} < 0 \) since adsorption is exothermic.
• \( ∆H_{mic} > 0 \) since micelle formation is endothermic.

Therefore, the correct answer is: \(∆H_{ads} < 0\ and\ ∆H_{mic} > 0\).