Matter-Buoyancy: Levitating Bubbles (Megan Whitaker)

Author

Megan Whitaker

Principle(s) Illustrated

1. Matter that can not be seen still has mass and takes up space.

2. Lower Density substances will float on higher density substances.

Standards

• 8.8.c- Students know the buoyant force on an object in a fluid is an upward force equal to the weight of the fluid the object has displaced.

• 8.8.d- Students know how to predict whether an object will sink or float.

• 8.3.d- Students know the states of matter (solid, liquid, gas) depend on molecular motion.

• 8.5.a- Students know reactant atoms and molecules interact to form products with

• different chemical properties.

• Questioning Script

Prior knowledge & experience:

1. Bubbles are filled with air and will float on the breeze.

2. Bubbles start off rising but will eventually sink to the ground.

3. Objects with lower density will float in fluids with a higher density.

4. Combining vinegar and baking soda will create bubbles.

Root question:

What is in the container that allows the bubbles to levitate and not sink to the bottom of the container? How is the density of the bubble different from the density of the substance in the container?

Target response:

The bubbles released by the baking soda and vinegar releases a gas into the container. This gas (carbon dioxide) is more dense than the surrounding air and sinks to the bottom of the container. When the bubbles are blown into the container the air inside them is less dense than the carbon dioxide and the bubbles will "float" on the surface of the carbon dioxide gas.

Common Misconceptions:

If a container appears to be empty, there is no matter in it.

Bubbles float in air because the gas inside the bubbles is lighter than air.

Gases are not a fluid, only liquids are fluids.

Supplies

1. Large clear sided tank or container

2. Wide low container (should fit inside the tank)

3. Baking Soda (Sodium Bicarbonate)

4. White Vinegar (Acetic Acid)

5. Bubbles

Photographs and Movies

Put all photos in the class Picasa Album and reference here. Do not upload the photos directly to this wiki as there is not enough memory in the website.

References

Reference 1 (give the title of the page and insert a link. Don't just paste URL)

Reference 1 (give the title of the page and insert a link. Don't just paste URL)