Which one of the following is not an application of adsorption?

Homogeneous catalysis

The correct answer is option 3. Homogeneous catalysis.

Let us explore each option in detail to understand how adsorption applies or does not apply in these contexts:

1. Separation of Inert Gases

Application of Adsorption: Adsorption can be used for separating gases, although it's more common for gases with different chemical properties. Inert gases like helium and neon are often separated using methods such as cryogenic distillation or membrane technologies. However, adsorption can still play a role in certain specialized separation processes where the differences in adsorption affinities are exploited.

2. In Curing Diseases

Application of Adsorption: Adsorption is indeed used in medicine, especially in the case of activated charcoal. Activated charcoal is a material with a very high surface area, making it effective at adsorbing toxins and drugs in the digestive system. This process helps to prevent the absorption of harmful substances into the bloodstream, making it a valuable tool in treating poisonings and overdoses.

3. Homogeneous Catalysis

Not an Application of Adsorption: Homogeneous catalysis involves catalysts that are in the same phase as the reactants, typically in a liquid phase. In this process, the catalyst facilitates a chemical reaction by interacting directly with the reactants. The key characteristic of homogeneous catalysis is that the catalyst and the reactants are uniformly mixed, which means there is no distinct solid phase where adsorption could occur.  In contrast, adsorption involves the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface. This process is a key feature of heterogeneous catalysis, where the catalyst is in a different phase (e.g., solid) from the reactants (e.g., liquids or gases). In heterogeneous catalysis, adsorption on the surface of the solid catalyst is crucial for the reaction to occur.

4. Chromatographic Analysis

Application of Adsorption: Chromatography is a technique that separates components of a mixture based on their differential interactions with a stationary phase. In adsorption chromatography, the stationary phase is a solid adsorbent (e.g., silica gel or alumina). Components of the mixture adsorb to varying degrees depending on their chemical properties, leading to separation. This separation is based on how strongly each component interacts with the adsorbent.

Summary

Homogeneous Catalysis is not an application of adsorption because the catalyst is in the same phase as the reactants, and adsorption is not a central mechanism in this process. Instead, adsorption is a significant feature in heterogeneous catalysis (where the catalyst is in a different phase) and in applications such as chromatographic analysis and curing diseases (e.g., using activated charcoal)