Heat — Question 24

The following experiment demonstrates that liquids expand on heating:

1. Take an empty bottle with a tight fitting cork with a hole drilled in its middle, a drinking straw, two bricks, a wire gauze and a burner.
2. Fill the bottle completely with water. Add few drops of ink to make it coloured.
3. Fix the cork in the mouth of the bottle. Pass the drinking straw through the cork. Put some molten wax around the hole to avoid leakage of water.
4. Pour some more water in the drinking straw so that water level in the straw can be seen. Mark the water level in the straw as shown in figure.
5. Place the bottle on the wire gauze kept over the two bricks. Heat the bottle using a burner as shown in figure.
6. Look at the level of water in the straw.

Conclusion — When water is heated more and more, the level of water in the drinking straw rises. This shows that water expands on heating.