Chapter 2: Is Matter Around Us Pure?
Suspensions & Colloids
What is a Suspension?
A suspension is a heterogeneous mixture where solute particles do not dissolve but remain suspended.
Properties of Suspension
| Property | Description |
|---|---|
| Type | Heterogeneous |
| Visibility | Particles visible to naked eye |
| Light | Scatters light (path visible) |
| Stability | Unstable — particles settle |
| Filtration | CAN be filtered |
Examples: Chalk in water, muddy water, flour in water
What is a Colloid?
A colloid is a heterogeneous mixture that appears homogeneous because particles are very small.
Properties of Colloid
| Property | Description |
|---|---|
| Type | Heterogeneous (appears homogeneous) |
| Particle Size | 1 - 1000 nm |
| Visibility | Cannot see particles |
| Light | Scatters light (Tyndall effect) |
| Stability | Stable |
| Filtration | Cannot be filtered |
💡 The Tyndall Effect - Diagram
How to Draw for Exam:
SOLUTION (No Tyndall) COLLOID (Tyndall Effect)
┌─────────────────┐ ┌─────────────────┐
│ ──────────→ │ │ ──•──•──•──→ │
│ (clear) │ │ (visible │
│ Light beam │ │ path) │
│ NOT visible │ │ Light SCATTERS │
└─────────────────┘ └─────────────────┘
📝 Exam Tip: Show scattered dots around beam in colloid, straight line in solution
Where We See Tyndall Effect:
- 🌲 Sunlight through forest canopy
- 🏠 Light beam in a dusty room
- 🌫️ Car headlights in fog
Components of Colloid
| Component | Description |
|---|---|
| Dispersed Phase | Solute-like particles |
| Dispersion Medium | Solvent-like medium |
Types of Colloids - Table for Exam
| Dispersed Phase | Medium | Type | Example |
|---|---|---|---|
| Liquid | Gas | Aerosol | Fog, clouds |
| Solid | Gas | Aerosol | Smoke |
| Gas | Liquid | Foam | Shaving cream |
| Liquid | Liquid | Emulsion | Milk |
| Solid | Liquid | Sol | Mud, paint |
Visualizer
Particles diffusing in Colloid
Particles move from high concentration to low concentration
Interactive Visualization