Short Answer

A suspension is a type of mixture in which solid particles are spread throughout a liquid but do not dissolve in it. The particles in a suspension are large enough to be seen with the naked eye and can settle down when the mixture is left undisturbed. Examples include muddy water, flour in water, and chalk powder in water.

Suspensions are not uniform mixtures, and their particles can be separated by filtration. When shaken or stirred, the particles spread out evenly, but after some time, they settle at the bottom due to gravity. Suspensions are commonly found in nature, homes, and industries.

Detailed Explanation

Suspension

A suspension is a heterogeneous mixture that contains solid particles spread throughout a liquid. Unlike solutions, where the solute dissolves completely, the solid particles in a suspension remain separate and visible. This gives suspensions their unique characteristics such as cloudiness, ability to scatter light, and settling of particles. Suspensions are common in daily life, nature, and industries, making them an important topic in chemistry.

In a suspension, the solid particles are usually larger than 1000 nanometres. Because of their large size, they do not dissolve; instead, they stay floating in the liquid for some time and eventually settle down. This behaviour distinguishes suspensions from solutions and colloids.

Suspensions are useful in many products such as medicines, paints, and food items. Understanding how suspensions form and behave helps us use them properly in different activities and industries.

Characteristics of a suspension

Suspensions have several important features:

1. Heterogeneous mixture

A suspension does not look uniform throughout. Different parts of the mixture may have different amounts of solid particles.

Example: Muddy water looks darker at the bottom where more soil settles.

2. Large particle size

The particles are large enough to be seen without a microscope. This makes the mixture appear cloudy or opaque.

3. Settling of particles

Suspended particles settle down when the mixture is left undisturbed due to gravity. This is called sedimentation.

Example: Soil settles at the bottom of muddy water after some time.

4. Scattering of light

Suspensions scatter light because of their large particles. This is known as the Tyndall effect.

5. Can be separated by filtration

Since the particles are big, they can be removed using filter paper or a sieve.

Example: Filtering muddy water removes sand and soil particles.

6. Need stirring to mix well

Suspensions must be shaken or stirred before use to spread the particles evenly.

Example: Some medicines need to be shaken before taking.

Examples of suspensions

Suspensions are found everywhere. Some common examples include:

• Chalk powder in water
• Sand in water
• Muddy river water
• Flour mixed with water
• Paints used for walls
• Certain medicines like antacid syrups
• Dust particles in air

These mixtures show the typical properties of suspensions.

How suspensions are formed

A suspension forms when a solid does not dissolve in a liquid but breaks into fine pieces that stay spread throughout the liquid for some time. Several factors affect how well a suspension forms:

1. Particle size

Larger particles settle faster, while smaller particles stay suspended longer.

2. Stirring or shaking

Stirring helps spread the particles evenly, but they will still settle after some time.

3. Density difference

If the solid is denser than the liquid, it settles more quickly.

4. Temperature

Higher temperature may increase or decrease settling depending on the solid and liquid properties.

Suspensions in daily life and industry

Suspensions play a useful role in many areas:

1. Medicines

Liquid medicines like antacids or some antibiotics are suspensions. They must be shaken before use to get the correct dose.

2. Food items

Mixtures like soup, juice with pulp, and batters (such as dosa batter) are suspensions.

3. Cosmetics

Face masks, lotions with scrubbing particles, and some creams are suspensions.

4. Construction

Cement-water mixtures and paints are examples of suspensions used in building work.

5. Environment

Rivers carry suspended soil, giving water a muddy appearance during rainfall.

Difference between suspension and solution

Understanding suspensions becomes easier when compared to solutions:

• In a solution, particles dissolve completely; in a suspension, they do not.
• Solutions are clear; suspensions are cloudy.
• Solutions cannot be filtered; suspensions can be filtered.
• Solutions do not settle down; suspensions settle down on standing.

These differences show why suspensions are considered heterogeneous mixtures.

Conclusion

A suspension is a heterogeneous mixture in which solid particles are spread throughout a liquid but do not dissolve. The particles are large, settle on standing, scatter light, and can be separated by filtration. Suspensions are common in nature, homes, industries, and medicines. Understanding suspensions helps us recognize how mixtures behave and how they can be used or separated in different situations.