Q1.
Can you think of any heterogeneous mixtures with a gas as one of the components?
Answer
Yes. Gases mix freely with one another, so a mixture of gases is almost always homogeneous — but if the other component is a solid or a liquid spread through the gas, the mixture is heterogeneous.
| Mixture | What is dispersed in the gas | Type |
|---|---|---|
| Smoke | Fine solid carbon and ash particles in air | Heterogeneous |
| Fog, mist, clouds | Tiny liquid water droplets in air | Heterogeneous |
| Dust in the air | Solid dust particles in air | Heterogeneous |
| Air freshener spray, an aerosol | Liquid droplets in air | Heterogeneous |
| Hydrogen and oxygen (rocket fuel) | Gas mixed with gas | Homogeneous |
Why most gas mixtures are homogeneous: Gas particles are very far apart and move freely in every direction at high speed, so within moments they spread evenly through the whole container and no part differs from any other. But a solid or a liquid particle floating in air is a separate phase with a visible boundary — you can point to where the smoke is and where it is not — so such mixtures are heterogeneous.