| Experiment 1: ice and water. | Place a piece of ice in a glass of water at room temperature. Ice is a solid with a fixed shape. When it melts it becomes a liquid that takes the shape of the glass. This shows that the same substance (water) changed its physical state without changing its chemical composition | Placepieceglassroom |
| Experiment 2: diffusion in air. | Put a few drops of perfume in one corner of a room. After a few minutes you can smell it in the opposite corner. The reason is that the perfume vapour particles spread between the air particles through their random motion | dropsperfumecornerroom |
| Experiment 3: compression. | - Fill a syringe with air
- close its nozzle with your finger and push the plunger. The air volume decreases easily. Repeat the test with water and the plunger becomes very hard to push
- and the water volume hardly changes. This shows that gases can be compressed and liquids cannot be compressed in a noticeable way
| Fillsyringeclosenozzle |