Problem 124 - A Complete Resource Book in Chemistry for JEE Main

Question

The term soption stands for (a) Adsorption (b) Absorption (c) Desorption (d) Both absorption and adsorption

Step-by-Step Solution

Answer

The term 'soption' stands for both absorption and adsorption.

Step 1: Understanding the Term

The term 'soption' refers to the process of attaching one substance to another. It is not a standalone process but a general term that can describe various types of interactions between phases, such as solids, liquids, and gases.

Step 2: Reviewing the Definitions

Let's consider the different processes: - **Adsorption** is when molecules stick to the surface of a solid or liquid. - **Absorption** involves the molecules being taken up into the bulk of a solid or liquid. - **Desorption** is the process by which a substance is released from or through a surface.

Step 3: Analyzing the Choices

Given the definition of 'soption,' it can encompass both adsorption (surface process) and absorption (bulk process) as they both involve the attachment or uptake of molecules. Desorption is the opposite of these processes.

Step 4: Identifying the Correct Answer

Based on the understanding that 'soption' includes both adsorption and absorption, the correct choice is the one which recognizes both processes together.

Key Concepts

Adsorption

Adsorption is a fascinating phenomenon where molecules from a gas or liquid accumulate on the surface of a solid or liquid. This process occurs when the attractive forces on the surface of the adsorbent draw in the adsorbate molecules. Adsorption is surface-based, meaning that only the molecules on the outermost layers of the solid are involved.
This process can be influenced by various factors, including temperature and pressure.

• An increase in pressure often encourages more adsorption, especially in gases, because more molecules are forced to come in contact with the adsorbent surface.
• Temperature, on the other hand, generally has the opposite effect. Higher temperatures provide more energy for molecules to move away from the surface, which can reduce adsorption.

Adsorption is crucial in many industrial applications, such as in catalysis and water treatment. In catalysis, for example, the reactants adsorb on the catalyst's surface, leading to enhanced reactions. In water treatment, activated carbon is a common adsorbent used to clean impurities due to its large surface area and ability to attract pollutant molecules.

Absorption

Absorption is often confused with adsorption, but the two are different. Absorption involves a substance being taken up into the volume or bulk of another phase, like a sponge soaking up water. In essence, absorption is a bulk phenomenon.
To visualize this, imagine pouring a liquid into a porous material. The liquid penetrates the interior, filling spaces within. This is absorption at work.

• In gases, absorption can involve a gas being dissolved into a liquid, such as carbon dioxide into water.
• For solids and liquids, the substance permeates, entering the interior structure of the absorbing material.

Temperature greatly influences absorption. For gases, lower temperatures often favor absorption into liquids because cooler conditions generally allow more gas to be dissolved.
Absorption plays a critical role in processes like digestion, where nutrients are absorbed into the bloodstream from food. Industrial applications include the use of absorbents to capture or contain substances, such as silica gel absorbing moisture in packaging.

Desorption

Desorption is the reverse of adsorption or absorption, where a substance is released from or through a surface. This process is significant when considering how to recover or recycle used materials.
For adsorption, desorption involves adsorbed molecules being liberated from the surface of a solid or liquid. Meanwhile, in absorption, it involves molecules leaving the bulk material.

• Desorption can be triggered by changing conditions, such as increasing the temperature, which provides molecules with the energy needed to break away from the surface or bulk.
• Lowering the pressure or introducing a chemical promoter can also assist in desorption, often used in industrial settings.

Desorption is integral to processes like temperature swing adsorption, commonly used in gas purification, where adsorbates are removed from adsorbent materials by altering temperature conditions. By understanding desorption, industries can enhance recycling and material purification processes, making them more efficient and sustainable.