This demonstration shows the thermal expansion of metals. A metal ball can pass through a ring at room temperature, but when heated, it expands and no longer fits. Cooling the ball in water allows it to contract and pass through again.

1. Begin with the ball and ring apparatus at room temperature; pass the ball through the ring to show it fits.
2. Heat the metal ball evenly with a Bunsen burner while rotating it for a few seconds.
3. Attempt to pass the heated ball through the ring; it will no longer fit because of expansion.
4. Cool the ball by placing it in a beaker of water.
5. After cooling, try passing the ball through the ring again; it will now fit.

Heat - Ball and Ring - Ong SK 1984:

Ball and ring expansion experiment - Chemistry with Mrs V:

📄 Ball and ring experiment - Sage: https://study.sagepub.com/chamberssouter3e/student-resources/chapter-8-types-of-matter/ball-and-ring-experiment

• None

• Safety glasses required when working with open flames.
• Be cautious of hot metal and boiling water when cooling the ball.

• Why does the ball no longer fit through the ring when heated? (Because metals expand when heated due to increased particle motion.)
• Why does cooling the ball allow it to fit again? (Cooling reduces particle motion, causing contraction.)
• What real-world examples use thermal expansion? (Expansion joints in bridges, bimetallic strips in thermostats.)