Q1.
Complete Table 5.1 and review what you have learnt about solutions, suspensions and colloids.
Answer
Table 5.1: Properties of different types of mixtures
| S. No. | Property | Solution | Suspension | Colloid |
|---|---|---|---|---|
| 1. | Nature (homogeneous / heterogeneous) | Homogeneous | Heterogeneous | Heterogeneous, though it looks homogeneous |
| 2. | Particle size | Less than 1 nm | More than 1000 nm | 1 – 1000 nm |
| 3. | Visibility | Particles not visible; the mixture is transparent | Particles visible to the naked eye | Particles not visible; the mixture looks uniform |
| 4. | Separation by filtration | Cannot be separated | Can be separated — leaves a residue | Cannot be separated |
| 5. | Settling | Does not settle | Settles on standing (sedimentation) | Does not settle |
| 6. | Tyndall effect | Not shown | Shown | Shown |
Examples: solution — salt or sugar in water, vinegar, brass; suspension — chalk powder in water, muddy water, sand in water; colloid — milk, blood, smoke, ice cream, cloud.
The single idea behind all six rows: particle size. Below 1 nm the particles are so small that they neither settle, nor get caught by filter paper, nor scatter light — everything about a solution follows. Above 1000 nm they are heavy enough to settle, big enough to be trapped by filter paper and visible to the eye. In between, a colloid inherits half of each list: it behaves like a solution when you filter it or let it stand, and like a suspension when you shine a beam of light through it.