Problem 83 - A Complete Resource Book in Chemistry for JEE Main

Question

Adsorption is a phenomenon, in which a substance (a) goes into the body of some other substance (b) accumulates on the surface of some other substance (c) remains close to some other substance (d) does not accumulate on the surface of some other substance

Step-by-Step Solution

Answer

Adsorption is described by option (b): accumulates on the surface of some other substance.

Step 1 - Understand the Problem

Read the question carefully to understand what is being asked. The question is asking about the definition of adsorption and which statement accurately describes this phenomenon.

Step 2 - Review Key Concepts

Adsorption is a surface phenomenon where molecules of a substance accumulate on the surface of a solid or liquid. This is different from absorption, where substances are taken into the body or volume of another substance.

Step 3 - Analyze Each Option

Evaluate each option based on your understanding of adsorption: - (a) goes into the body of some other substance: This describes absorption, not adsorption. - (b) accumulates on the surface of some other substance: This correctly describes adsorption. - (c) remains close to some other substance: This is vague and does not specifically describe adsorption. - (d) does not accumulate on the surface of some other substance: This is the opposite of adsorption.

Step 4 - Select the Correct Option

Based on the analysis, option (b) 'accumulates on the surface of some other substance' correctly describes adsorption.

Key Concepts

Surface Phenomenon

Adsorption is a classic example of what is known as a "surface phenomenon." This means that the process primarily takes place at the surface of a material, rather than throughout its whole body. In adsorption, the molecules of a substance, known as the adsorbate, stick to the surface of another material. The substance whose surface is being used is called the adsorbent.

This entire process is very different from what occurs in the body, such as absorbing nutrients in our stomach, which involves deeper interactions. In adsorption:

• The interaction is mainly at the material's surface.
• There is no significant penetration into the material's bulk.
• The strength of the interaction is crucial for how well a substance is adsorbed.

Adsorption is utilized in many applications, such as in water purification systems. Here, harmful molecules are "captured" from water by adsorbing them onto certain materials. The surface of the adsorbing material plays a central role and determines the efficiency of this process.

Adsorption vs Absorption

Adsorption and absorption may sound similar, but they describe two entirely different processes. Understanding the difference is key to grasping the concepts.

• Adsorption: This process involves substances accumulating on the surface. The adsorbate molecules do not penetrate deeply into the material they are on. For example, activated charcoal adsorbing toxins from water is a typical adsorption process. Here, the toxins cling to the surface of the charcoal.
• Absorption: In this case, the substance penetrates deeply into the body or volume of another substance. Think of a sponge soaking up water, where the water is absorbed into every pore of the sponge.

A simple way to remember the difference: Adsorption happens on the surface, while absorption involves moving into the volume. These differences are crucial in various fields like chemistry, environmental science, and industrial processes.

Adsorption Definition

The formal definition of adsorption describes it as a process where molecules from a gas, liquid, or dissolved solid collect on a surface. Unlike absorption, where a substance completely takes in another, adsorption only occurs at the interface.

Several factors influence adsorption:

• Nature of the adsorbate and adsorbent - Some materials naturally interact better with each other. This affects how well adsorption occurs.
• Surface area of the adsorbent - Larger surface areas provide more room for molecules to adhere.
• Temperature and pressure - Lower temperatures and higher pressures generally enhance adsorption.

Adsorption plays a significant role in everyday life and industrial applications. From air filters that capture odors and pollutants to drug delivery systems in medicine, understanding adsorption helps in designing better systems and solutions.