Problem 12 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

Among the colloids cheese (C), milk (M) and smoke (S), the correct combination of the dispersed phase and dispersion medium, respectively is:(a) \(\mathrm{C}\) : liquid in solid; \(\mathrm{M}\) : liquid in solid; \(\mathrm{S}\) : solid in gas (b) \(\mathrm{C}\) : liquid in solid; \(\mathrm{M}\) : liquid in liquid; \(\mathrm{S}\) : solid in gas (c) C : solid in liquid; M : liquid in liquid; \(\mathrm{S}\) : gas in solid (d) \(\mathrm{C}\) : solid in liquid; \(\mathrm{M}\) : solid in liquid; \(\mathrm{S}\) : solid in gas

Step-by-Step Solution

Answer

The correct option is (b).

Step 1: Understanding Colloids

A colloid is a mixture where one substance of microscopically dispersed insoluble particles is suspended throughout another substance. Colloids have two phases: a dispersed phase (the particle) and a dispersion medium (the continuous phase).

Step 2: Identifying Colloid for Cheese

Cheese has a dispersed phase of liquid (fat or protein micelles) within a solid matrix (water, fat-soluble vitamins, and minerals). Therefore, cheese is categorized as a colloid where liquid is dispersed in a solid medium.

Step 3: Identifying Colloid for Milk

Milk consists of fat globules dispersed in a water-based continuous medium, making it a liquid in liquid colloid, as both phases are in the liquid state.

Step 4: Identifying Colloid for Smoke

Smoke consists of solid particles dispersed within a gas, which makes it a colloid described as solid in gas.

Step 5: Compare Options

Review the combinations given in options: Option (b) is the only set that accurately describes cheese as liquid in solid, milk as liquid in liquid, and smoke as solid in gas.

Key Concepts

Dispersed Phase

In colloids, the dispersed phase refers to the substance that is scattered or distributed as fine particles or droplets within another substance. These particles don't settle out quickly, distinguishing colloids from ordinary mixtures. The dispersed phase can be solid, liquid, or gas, depending on the type of colloid. For instance:

• In milk, the dispersed phase consists of fat globules scattered throughout the liquid.
• In cheese, liquid droplets like fats and proteins form the dispersed phase within a solid matrix.
• In smoke, tiny solid particles are the dispersed phase distributed in the air (a gas).

Understanding the nature of the dispersed phase helps identify and categorize colloids effectively.
Recognizing how these particles remain dispersed without settling is crucial for applications in food, medicine, and industry.
It provides insight into the behavior and characteristics of colloidal systems.

Dispersion Medium

The dispersion medium, or continuous phase, is the substance in which the dispersed phase is suspended. This phase provides a supportive environment that allows the particles of the dispersed phase to remain distributed throughout the mixture. Like the dispersed phase, the dispersion medium can also be solid, liquid, or gas.

• In cheese, the dispersion medium is solid, containing water, vitamins, and minerals.
• For milk, the dispersion medium is liquid, primarily water.
• In smoke, air acts as the gaseous dispersion medium.

The interactions between dispersed and continuous phases determine the stability and properties of a colloid.
Different combinations of dispersed and dispersion mediums result in various types of colloids, affecting their appearance and functional characteristics.
Understanding the dispersion medium is vital for manipulating and employing colloids in practical applications.

Types of Colloids

Colloids are classified based on the states of their dispersed phase and dispersion medium. Recognizing these types helps understand their properties and applications. Here are some key combinations:

• Liquid in Solid: Cheese is an example, where a liquid dispersed phase exists in a solid matrix, making it a "gel" type of colloid.
• Liquid in Liquid: Milk demonstrates this as an "emulsion," with liquid fat globules in a liquid water-based medium.
• Solid in Gas: Smoke represents an "aerosol," comprising solid particles distributed in a gaseous environment.

Familiarity with these types helps identify product formulations and predict how colloids will behave in different conditions.
These distinctions make it easier to apply colloidal principles to areas like food science, pharmaceuticals, and environmental science.
Each type of colloid possesses unique properties that affect its use and effectiveness in various scenarios.