Types of Mixtures and Their Properties
Mixtures are classified into three main types based on the size of particles and their behavior in a dispersing medium: Solutions, Colloids, and Suspensions.
1. Solutions (True Solutions)
A solution is a homogeneous mixture in which one substance (solute) dissolves completely in another (solvent). The particles are too small to be seen with the naked eye and do not settle down.
Components of a Solution
Solute: The substance that dissolves in a solvent. (e.g., Salt in saltwater)
Solvent: The substance in which the solute dissolves. (e.g., Water in saltwater)
Properties of True Solutions
✅ Homogeneous in nature (uniform composition).
✅ Particles are very small (less than 1 nm).
✅ Transparent and does not scatter light (no Tyndall effect).
✅ Solute particles do not settle down.
✅ Cannot be separated by filtration but can be recovered by evaporation.
Examples of True Solutions
🔹 Sugar dissolved in water
🔹 Saltwater
🔹 Air (a mixture of gases like oxygen and nitrogen)
Concentration of a Solution
The concentration of a solution refers to the amount of solute dissolved in a given amount of solvent. It can be classified as:
Dilute Solution: Contains a small amount of solute.
Concentrated Solution: Contains a large amount of solute.
Saturated Solution: Contains the maximum amount of solute that can dissolve at a given temperature.
2. Colloids
A colloid is a heterogeneous mixture in which tiny particles of one substance are dispersed in another. The particles are larger than those in a solution but smaller than those in a suspension.
Properties of Colloids
✅ Heterogeneous in nature but appears homogeneous to the naked eye.
✅ Particles do not settle down.
✅ Exhibits the Tyndall effect (scatters light).
✅ Cannot be separated by filtration but can be separated by special techniques like centrifugation.
Examples of Colloids
🔹 Milk (liquid in liquid)
🔹 Fog (liquid in gas)
🔹 Blood (solid in liquid)
🔹 Jelly (solid in liquid)
| Dispersing Medium | Dispersed Phase | Example |
|---|---|---|
| Gas | Liquid | Fog, Mist |
| Gas | Solid | Smoke, Dust in air |
| Liquid | Gas | Foam (Shaving cream) |
| Liquid | Liquid | Milk, Mayonnaise |
| Liquid | Solid | Paint, Ink |
| Solid | Liquid | Jelly, Butter |
| Solid | Solid | Coloured Glass, Alloys |
3. Suspensions
A suspension is a heterogeneous mixture in which the solute particles are large and do not dissolve in the solvent. The particles are visible to the naked eye and settle down over time.
Properties of Suspensions
✅ Heterogeneous in nature.
✅ Particles are large enough to be seen.
✅ Particles settle down over time.
✅ Blocks light but does not show the Tyndall effect.
✅ Can be separated by filtration.
Examples of Suspensions
🔹 Sand in water
🔹 Flour in water
🔹 Muddy water
🔹 Chalk powder in water
Comparison of Solutions, Colloids, and Suspensions
| Property | Solution (True Solution) | Colloid | Suspension |
|---|---|---|---|
| Particle Size | Very small (<1 nm) | Intermediate (1-100 nm) | Large (>100 nm) |
| Nature | Homogeneous | Appears homogeneous, but is heterogeneous | Heterogeneous |
| Settling of Particles | Does not settle | Does not settle | Settles down over time |
| Tyndall Effect | No | Yes | No |
| Filtration | Cannot be filtered | Cannot be filtered | Can be filtered |