Colloids & Suspensions
Q10: Explain colloids and suspensions as mixtures and give examples of each.
Suspension
Definition
A suspension is a mixture where solid particles spread through a liquid but do not dissolve.
Examples
- Chalk and water
- Muddy water
- Milk of magnesia
- Sand in water
- Flour in water
Properties
- Particles are large and visible.
- Can be separated using filtration.
- Particles settle over time.
- Suspensions scatter light (Tyndall effect).
Study Example
Shaking chalk powder with water creates a milky suspension. The chalk settles over time, and filtration separates it from water. A light beam scatters in the suspension.
Colloids
Definition
A colloid is a mixture where the solute particles are smaller than in suspensions but larger than in solutions.
Examples
- Soap solution
- Starch solution
- Milk
- Ink
- Blood
- Jelly
Properties
- Looks uniform but is actually heterogeneous.
- Particles are too small to see.
- Passes through filter paper.
- Particles do not settle over time.
- Scatters light (Tyndall effect).
Study Example
Shaking soap powder in water forms a stable colloidal solution. The particles do not settle, cannot be filtered out, and scatter light.
Tyndall Effect
The Tyndall effect is when light scatters in a colloid but not in a true solution.
Comparison
| Property | Solution | Colloid | Suspension |
|---|---|---|---|
| Particle Size | Less than 1 nm | 1 - 100 nm | Greater than 100 nm |
| Visibility | Not visible | Not visible | Visible |
| Filtration | Passes through | Passes through | Does not pass |
| Stability | Stable | Stable | Unstable |
| Tyndall Effect | No | Yes | Yes |
3. Write down the difference between a solution, a colloid, and a suspension, including the particle sizes and properties of each.
Types of Mixtures
Solution
A solution is a uniform mixture where one substance dissolves in another. The particles are super tiny (less than 1 nanometer). Solutions look clear and never separate. Example: saltwater.
Colloid
A colloid is a mixture with small particles spread throughout. The particles are between 1 nanometer and 1 micrometer in size. Colloids look cloudy but don't settle. They also show the Tyndall effect (light scattering). Example: milk.
Suspension
A suspension is a mixture where bigger particles float in a liquid or gas. The particles are larger than 1 micrometer. Suspensions look cloudy, and the particles settle over time. Example: muddy water.
4. Provide real life examples of a suspension and explain why its particles settle over time.
Suspension Example
Ans: Muddy water.
Explanation: In a suspension, the particles are big and heavy. They do not dissolve. Over time, gravity pulls them down. This makes them settle at the bottom. They are too large to stay floating forever.
Colloids, Suspensions, and Their Comparison
I. Colloids
- A. Definition: Heterogeneous mixtures with solute particles larger than true solutions but not visible to naked eye
- B. Characteristics:
- 1. Particle size: 1-1000 nm
- 2. Remain dispersed without settling
- 3. Scatter light (Tyndall effect)
- C. Examples: Starch, albumin, soap solutions, blood, milk, ink, jelly, toothpaste
II. Suspensions
- A. Definition: Heterogeneous mixture of undissolved solid particles in a liquid medium
- B. Characteristics:
- 1. Particle size: < 1000 nm
- 2. Visible to naked eye
- 3. Settle over time
- C. Examples: Chalk in water, paints, milk of magnesia
III. Comparison of Solutions, Colloids, and Suspensions
| Characteristic | Solution | Colloid | Suspension |
|---|---|---|---|
| Homogeneity | Homogeneous | Heterogeneous | Heterogeneous |
| Particle size | < 1 nm | 1-1000 nm | > 1000 nm |
| Visibility | Not visible | Not visible | Visible |
| Filtration | Particles can pass through normal as well as ultra-filter paper | Passes normal filter paper, not ultra-filter paper | Cannot pass filter papers |
| Light scattering | No | Yes (Tyndall effect) | Yes |
| Separation | Does not separate | Does not separate | Separates when stationary |
| Example | Salt Water | Soup Water | Muddy water |
IV. Key Points Summary
Summarizes main concepts from the provided content
V. Review Questions
Includes multiple-choice and short answer questions
VI. Think Tank and Project
- A. Analytical questions about solutions and colloids
- B. Poster project on forms of matter in everyday environment