Density & Bouancy-Ice in Alcohol (Paul DeCunzo)

• 8b. Students know how to calculate the density of substances (regular and irregular

• solids and liquids) from measurements of mass and volume.

• 8c. Students know the buoyant force on an object in a fluid is an upward force equal

Target response:

Density: "It will float."Materials that are less dense than water (or have a density lower than 1.00 g/cm3) will float in water, while materials that are more dense than water (or have a density greater than 1.00 g/cm3) sink. The same is true of any liquid, such as ethyl alcohol with a density of 0.79 g/cm3. Materials less dense than ethyl alcohol will float in it, while materials more dense will sink. Therefore as observed in this demonstration, ice with a density of 0.92 g/cm3 will float in water but will sink in ethyl alcohol.

Bouyancy: the weight of water displaced is greater than the weight of the ice cube. The weight of the alcohol displaced is less than the ice cube so the alcohol cannot support the ice and the ice sinks

Soubility: Food coloring is soluble in water but not the alcohol.

Extension Demonstrations

The ice will float between layers and after melting will drip to the bottom.

References

Reference 1:

Flinn Scientific Demo Directions

Reference2:

Phet Simulation-Sink or Float) Bouancy Lesson Handout