Question

Match the following | Column-I | | :--- | | (a) Butter | | (b) Pumice | | stone | | (c) Milk | | (d) Paints | Column-II (p) Dispersion of liquid in liquid (q) Dispersion of solid in liquid (r) Dispersion of gas in solid (s) Dispersion of liquid in solid

Short answer

(a) Butter - (s), (b) Pumice - (r), (c) Milk - (p), (d) Paints - (q)

Step-by-step solution

Understanding Scientific Terminology

Read the items in both columns. 'Dispersion' refers to a mixture of two or more different states of matter. Recognize that when studying colloids, dispersion mediums range from liquids, solids, or gases.

Match Column-I with Column-II

Identify each substance in Column-I to see which type of colloidal dispersion it represents. For example, butter and paints are dispersions of liquid in solid and liquid, respectively; milk is a dispersion of liquid in liquid; pumice stone is a solid foamy material, implying dispersion of gas in solid.

Evaluate Individual Matches

For (a) Butter - recognize it's a solid fat with liquid dispersed in solid, aligning it to (s). For (b) Pumice stone - recognize gas pockets in solid, aligning to (r). (c) Milk is an emulsion of fats in water, aligning to (p). (d) Paints usually have solids in liquid, aligning to (q).

Correctly List the Matches

Based on the evaluations, the matches are: (a) Butter - (s) Dispersion of liquid in solid (b) Pumice stone - (r) Dispersion of gas in solid (c) Milk - (p) Dispersion of liquid in liquid (d) Paints - (q) Dispersion of solid in liquid

Key concepts

Dispersion in Colloids

Colloids are fascinating mixtures where one substance is dispersed evenly throughout another. The particle sizes in colloids tend to be quite small, usually ranging between 1 and 1000 nanometers. This unique quality leads to interesting properties, such as the scattering of light known as the Tyndall effect.
In colloids, the dispersed substance can appear in various states:

• Liquid in Liquid: Often called emulsions, an example is milk, where fat droplets are dispersed in water.
• Solid in Liquid: Paints exemplify this type, where solid pigment particles are distributed evenly throughout a liquid.
• Gas in Solid: Seen in pumice stones, where gas bubbles are trapped within a solid matrix.
• Liquid in Solid: Butter is a great example, where water droplets are dispersed in a solid fat.

Recognizing the type of dispersion helps in identifying the nature of the colloid, as seen in various everyday examples around us.

States of Matter

Matter primarily exists in three states: solid, liquid, and gas. Each state has distinctly different properties due to the arrangement and energy of the particles. Understanding these states is crucial in explaining colloidal dispersions.

• Solids: Particles are tightly packed, often making them rigid. Examples include salt and pumice.
• Liquids: Particles have more freedom to move, but still stay closely packed, as seen in milk and water.
• Gases: Particles are widely spaced, moving freely and filling the entire volume of any container, like the air we breathe.

Colloidal dispersions demonstrate combinations of these states. For example, a solid like butter contains liquid particles, showcasing the interaction and transitional nature of matter states.

Emulsions

Emulsions are a special type of colloidal system where liquid droplets are dispersed within another liquid. These systems often require emulsifying agents to stabilize them.
In an emulsion:

• The liquid dispersed is in small droplets, which doesn’t easily mix with the continuous phase.
• Common examples include milk (an emulsion of fat in water) and mayonnaise.

Emulsions can be of two types:

• Oil in Water (O/W): Oil droplets dispersed in water, commonly seen in milk.
• Water in Oil (W/O): Water droplets in oil, as seen in butter.

Emulsions are critical in food science, cosmetics, and pharmaceuticals, as they allow components to mix that otherwise remain separate.