Problem 170 - A Complete Resource Book in Chemistry for JEE Main

Question

$$ \begin{aligned} &\text { Match the following }\\\ &\begin{array}{ll} \hline \text { Column-I } & \text { Column-II } \\ \hline \text { (a) Dialysis } & \text { (p) Cleansing action of soap } \\ \text { (b) Peptisation } & \text { (q) Coagulation } \\ \text { (c) Emulsification } & \text { (r) Colloidal sol formation } \\ \text { (d) Electrophoresis } & \text { (s) Purification } \\ \hline \end{array} \end{aligned} $$

Step-by-Step Solution

Answer

(a) - (s), (b) - (r), (c) - (p), (d) - (q)

Step 1: Understanding the Terms

To match the terms from Column-I with those in Column-II, we need to understand the meaning of each term. Dialysis refers to a process used to separate small molecules from colloids, mainly for purification. Peptization is a process of converting a precipitate into a colloidal sol by adding an electrolyte. Emulsification is the process of making an emulsion, a colloidal-sized mixture of two immiscible liquids, often assisted by soaps. Electrophoresis is the movement of colloidal particles under the influence of an electric field for properties like coagulation.

Step 2: Matching Dialysis

Dialysis is a process of purification used to remove impurities and separate small molecules in solution. This matches with the term 'purification' in Column-II, which is represented by (s). Thus, (a) Dialysis - (s) Purification.

Step 3: Matching Peptisation

Peptization involves the formation of a colloidal sol from a precipitate by adding a suitable electrolyte. This matches with the term 'colloidal sol formation' in Column-II, which is represented by (r). Thus, (b) Peptisation - (r) Colloidal sol formation.

Step 4: Matching Emulsification

Emulsification is the process where two immiscible liquids are mixed to form a colloidal solution, like soaps create emulsions for cleansing. This matches with the term 'cleansing action of soap' in Column-II, which is represented by (p). Thus, (c) Emulsification - (p) Cleansing action of soap.

Step 5: Matching Electrophoresis

Electrophoresis refers to the coagulation and movement of charged colloidal particles in an electric field. This matches with the term 'coagulation' in Column-II, which is represented by (q). Thus, (d) Electrophoresis - (q) Coagulation.

Key Concepts

Dialysis

Dialysis is an essential process used for separating small molecules from larger colloidal particles. Think of it as a purification technique. During dialysis, a porous membrane is used, which allows only smaller molecules and ions to pass through, while larger colloidal particles are retained. This makes it an efficient method for removing impurities such as salts from colloidal solutions. In practical applications, dialysis is widely used:

• In medical treatments for patients with kidney failure, where it helps remove waste and excess substances from the blood.
• In laboratories when purifying proteins.

By understanding dialysis, we gain insight into its crucial role in both biological and industrial settings.

Peptisation

Peptisation is a fascinating phenomenon where a precipitate is transformed into a colloidal sol. This transformation is induced by adding a small amount of an electrolyte, which enhances the stability of colloidal particles. Here's how it works:

• The precipitate, often composed of aggregates, relies on the added electrolyte to disperse into fine colloidal particles.
• These particles are stabilized by the adsorbed ions from the electrolyte, preventing them from recombining.

Peptisation is significant because it explains how colloidal solutions form and stay in a dispersed state. Understanding this concept helps in crafting stable colloids for various applications, including paints and medicines.

Emulsification

Emulsification is the process of mixing two immiscible liquids, like oil and water, to form a stable emulsion. In this process, a third substance known as an emulsifier (often soaps or detergents) is crucial. Here’s what happens during emulsification:

• The emulsifier reduces the surface tension between the liquids, enabling them to mix and form tiny droplets.
• These droplets are stabilized by the emulsifier, which has a hydrophilic (water-attracting) and a hydrophobic (water-repelling) end.
• This dual nature allows the emulsifier to interact with both liquids, keeping them dispersed.

Emulsification is fundamental in various products like:

• Food items - mayonnaise and creams.
• Cosmetics - skin lotions and creams.
• Cleansing products - soaps utilize emulsification for effective cleaning.

Electrophoresis

Electrophoresis involves the movement of charged colloidal particles through a fluid under the influence of an electric field. This process is instrumental in separating particles based on their charge and size. During electrophoresis:

• Particles acquire a charge by adsorbing ions from the surrounding medium.
• When an electric field is applied, these charged particles migrate towards the electrode of opposite charge.

Electrophoresis is prominent in various applications, especially in the field of biochemistry:

• It is used for the separation of DNA, RNA, and protein molecules during laboratory analysis.
• In water treatment, it helps in removing charged particles from colloidal suspensions.

This process exemplifies the interplay of chemistry and physics, making it a robust tool in scientific analysis.

Coagulation

Coagulation is the process of bringing together colloidal particles to form a less stable and larger form called a "floc." This often leads to the separation or settling of particles from the dispersion medium. Key aspects of coagulation:

• Coagulation is induced by adding electrolytes that neutralize the charge on the colloidal particles, causing them to aggregate.
• This is crucial in water purification, where suspended particles are removed to achieve clear water.
• Coagulation also finds its use in the food industry for products like cheese, where milk proteins are coagulated to form the final product.

Coagulation is an essential step in many industrial processes, ensuring the efficient separation of dispersed particles from mixtures.