Physics – 2.2.1 Thermal expansion of solids, liquids and gases | e-Consult

Here's a description of an experiment to demonstrate the difference in expansion between a solid, a liquid, and a gas when heated equally:

Materials:

• Three identical containers (e.g., glass jars or flasks)
• A small amount of water (liquid)
• A small amount of polystyrene foam (solid)
• Air (gas)
• A heat source (e.g., a hot plate or Bunsen burner)
• Thermometer
• Measuring cylinder
• Stopwatch

Procedure:

1. Measure Initial Volumes: Measure the initial volume of water, polystyrene foam, and air in their respective containers using a measuring cylinder. Record these initial volumes.
2. Heat the Containers: Place each container on the heat source and heat them equally for a set period (e.g., 5 minutes). Monitor the temperature of the containers using a thermometer. Ensure the temperature is the same for all three containers.
3. Measure Final Volumes: After the heating period, carefully measure the final volume of water, polystyrene foam, and air in their containers using the measuring cylinder. Record these final volumes.
4. Calculate Volume Changes: Calculate the change in volume for each substance by subtracting the initial volume from the final volume.
5. Compare Results: Compare the volume changes observed for the solid, liquid, and gas. You should observe that the gas undergoes the largest expansion, followed by the liquid, and then the solid undergoes the smallest expansion.

Observations:

• The polystyrene foam will expand, but its expansion will be minimal.
• The water will expand, but its expansion will be less than that of the gas.
• The air (gas) will expand significantly, resulting in a large increase in volume.

Conclusion: This experiment demonstrates that gases expand significantly more than liquids, and liquids expand more than solids, when heated equally. This is because the particles in gases have more freedom of movement and are less strongly bound together than the particles in liquids and solids.