Floating Coin on Water

Aluminum coins, though denser than water, can be floated on the water’s surface due to surface tension.

1. Fill a clean bowl or beaker with water.
2. Add a drop of food coloring to the water to make the water surface more visible.
3. Gently set an aluminum coin (such as a yen or old French franc) on on the surface with a tissue or fork.
4. Observe the curvature of the water surface around the coin from the side view.

Floating Coins Experiment - Taras Kul:

How to float coins on water - Suhani Sharma:

📄 Floating Coins - University of Waterloo: https://uwaterloo.ca/chem13-news-magazine/september-2013/feature/floating-coins

• Try floating coins made of different metals to test how density and thickness affect floating.
• Use other small lightweight objects, such as paper clips or needles, to demonstrate surface tension.
• Measure the maximum size or weight of coin that can still float on water.
• Repeat the experiment with liquids other than water (such as ethanol or saltwater) to compare surface tension.

• No hazardous chemicals are used, but spills should be cleaned immediately to avoid slippery surfaces.
• Handle coins carefully to avoid dropping them into glassware, which may crack or break.

• Why can aluminum coins float on water even though their density is greater than that of water?
• How does surface tension differ between water and other liquids?
• What might happen if soap is added to the water? Why?