Colloidal Solution in Chemistry | Class 9 Science Notes, Properties, Examples & Tyndall Effect pdf note
Class: 9 Science | Subject: Chemistry
A Colloidal Solution is a heterogeneous mixture in which the particle size lies between a true solution and a suspension. Colloids are very important in chemistry because they show unique properties such as the Tyndall Effect and Brownian Movement.
What is a Colloidal Solution?
A Colloidal Solution is a heterogeneous mixture containing two components:
- Dispersed Phase: The substance present in smaller quantity.
- Dispersion Medium: The substance in which particles are dispersed.
The particle size ranges from 1 nm to 1000 nm.
Characteristics of Colloidal Solution
- ✔ Heterogeneous mixture
- ✔ Particle size between 1–1000 nm
- ✔ Particles cannot be seen with naked eyes
- ✔ Stable in nature
- ✔ Do not settle down on standing
- ✔ Cannot be separated by ordinary filter paper
- ✔ Show Tyndall Effect
- ✔ Exhibit Brownian Movement
Particle Size Comparison
| Mixture | Particle Size |
|---|---|
| True Solution | Less than 1 nm |
| Colloidal Solution | 1 – 1000 nm |
| Suspension | More than 1000 nm |
Tyndall Effect
The Tyndall Effect is the scattering of light by colloidal particles.
When a beam of light passes through a colloidal solution, the path of light becomes visible because the particles scatter light.
Examples
- Milk
- Fog
- Smoke
- Mist
Brownian Movement
Colloidal particles move continuously in a random zig-zag motion.
This random movement is called Brownian Movement.
Brownian movement helps in maintaining the stability of colloidal solutions.
Properties of Colloidal Solution
- Particles remain suspended for a long time.
- Cannot be separated by ordinary filtration.
- Scatter light.
- Remain stable without settling.
Examples of Colloidal Solutions
- Milk
- Blood
- Tomato Sauce
- Ice Cream
- Whipped Cream
- Fog
- Clouds
- Mist
- Smoke
Coagulation
Coagulation is the process of making colloidal particles settle down.
It can be done by:
- Heating
- Cooling
- Adding a coagulating agent
Difference Between True Solution, Colloid and Suspension
| Property | True Solution | Colloid | Suspension |
|---|---|---|---|
| Nature | Homogeneous | Heterogeneous | Heterogeneous |
| Particle Size | <1 nm | 1–1000 nm | >1000 nm |
| Tyndall Effect | No | Yes | Yes |
| Settling | No | No | Yes |
| Filtration | No | No | Yes |
Frequently Asked Questions (FAQs)
What is a colloidal solution?
A colloidal solution is a heterogeneous mixture whose particle size ranges from 1 nm to 1000 nm.
What is the Tyndall Effect?
The scattering of light by colloidal particles is called the Tyndall Effect.
What is Brownian Movement?
Brownian Movement is the random zig-zag movement of colloidal particles.
Can colloidal particles be separated by filter paper?
No. Ordinary filtration cannot separate colloidal particles.
Summary
- ✔ Colloidal Solution is a heterogeneous mixture.
- ✔ Particle size ranges from 1 nm to 1000 nm.
- ✔ Shows Tyndall Effect.
- ✔ Exhibits Brownian Movement.
- ✔ Stable in nature.
- ✔ Cannot be separated by ordinary filtration.
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