Two beakers contain clear, colorless liquids - water and ethyl alcohol. An ice cube floats in the water but sinks in the alcohol because of the lower density of ethanol.

1. Fill one beaker with ~100 mL of water and another with ~100 mL of ethyl alcohol.
2. Show students two similar-sized ice cubes.
3. Place one ice cube into each beaker.
4. Observe: the ice cube floats in water but sinks in alcohol.
5. Ask students to propose hypotheses explaining why the outcomes differ.

Density - Ice in Alcohol & Water - Bond with James:

📄 Case of the Sunken Ice Cube - Flinn Scientific: https://www.flinnsci.com/api/library/Download/b5fd3e87e1b148e1a8eaf73296fb9d2f?srsltid=AfmBOop33Q9uNtq5gDs5tpRPz_Y64pRN6yLY0JwncSz1AuUw3SyfP1sx

• Mix water and alcohol in varying ratios to find the composition where the ice cube is suspended in the middle.
• Have students calculate the density of both liquids by measuring mass and volume.
• Compare with other liquids (oil, salt water, corn syrup).
• Discuss why ice floats in water, even though most solids are denser than their liquids.
• Explore seawater vs. freshwater densities (1.03 g/cm³ vs. 1.00 g/cm³) and buoyancy in lakes vs. oceans.

• Ethyl alcohol is flammable—keep away from flames and sparks.
• Wear chemical splash goggles and an apron.
• Handle glassware carefully to avoid spills and breakage.
• Dispose of liquids according to local regulations.

• Why does ice float in water but sink in alcohol?
• What role does density play in determining whether something floats or sinks?
• How does hydrogen bonding explain the unusual behavior of water when it freezes?
• Is it easier to float in freshwater or seawater, and why?