Soda Bottle Science Experiments, by John Cowens

Here are some additional experiments that use recycled two-liter soda bottles as miniature science labs.

Experiment #1: Liquid Fireworks
Water is denser than oil and the two will always separate from each other. Since food coloring is made mostly of water, it will drop through the oil and finally disperse into the water. This experiment produces "liquid fireworks."

Materials:

  • Baby oil
  • Small bottle or small plastic prescription vial
  • Tablespoon
  • Two-liter bottle with top 7.5 cm removed (save this part to use as a funnel)
  • Water

Procedure:

  1. Place 1 tablespoon of baby oil into the small bottle or plastic prescription vial.

  2. Add 2-3 drops of each different food coloring into the bottle or vial (example: 2-3 drops of red, 2-3 drops of blue, 2-3 drops of green and 2-3 drops of yellow).

  3. Secure the lid and shake until the all the ingredients have mixed together.

  4. Fill the two-liter bottle almost full with tap water.

  5. Pour the food coloring and baby oil mixture from the small bottle through the funnel and into the container of water.

  6. Observe the interactions of the liquids.

Explanation:
When the bubbles sink, their oil coating rises back to the surface. The color seems to disappear because the drops of coloring are not powerful enough to change the color of the water.

Experiment #2: Bubble Machine
Bubbles can be a thin, ball-shaped film of liquid that has a gas trapped inside. Air inside the bubble pushes outward against the watery "skin." Simultaneously, Earth's atmosphere pushes inward on the outside of the liquid "skin." This equal balance of two forces creates a shape with boundaries at an equal distance from the center and produces only one shape – a sphere. Here's a fun way to make bubbles.

Materials:

  • Medium-size bowl
  • Water
  • Blue or green liquid dishwashing soap
  • Granulated white sugar
  • Top half of a two-liter soda bottle (cut to resemble a funnel without the cap)
  • Teaspoon

Procedure:

  1. Fill the medium-size bowl halfway with water.

  2. Add several squirts of liquid dish soap and one teaspoon of sugar to the water.

  3. Stir the mixture thoroughly and vigorously until small bubbles appear. Add more liquid soap if needed.

  4. Dip the nozzle of the funnel into the soap solution. Lift it up and blow through the large opening toward the inside of the nozzle. If no bubbles appeared, repeat and/or add more liquid soap to the bowl of water.

  5. Dip the large open end of the funnel into the soap solution and blow through the nozzle.

Which end of the funnel produced the best bubbles?

Experiment #3: Waltzing Raisins
Drop raisins into a bottle of clear-colored soda and watch them rise, fall and hover for several minutes. This experiment is what I call "variation on a theme."

Materials:

  • Two-liter soda bottle
  • Water
  • Vinegar
  • Baking soda
  • Box of raisins
  • Tablespoon

Procedure:

  1. Fill the two-liter bottle half-full of water.

  2. Add 4 tablespoons of vinegar and 3 tablespoons of baking soda into the water. (You'll observe a chemical reaction as vinegar and baking soda interact – carbon dioxide bubbles will be produced.)

  3. Drop a few raisins into the bottle of water. The raisins may sink at first, but will "waltz" around soon thereafter.

Explanation:
The vinegar and baking soda produce carbon dioxide bubbles, which gather under the raisins until there's enough to make the raisins rise to the surface. When the raisins reach the surface, the bubbles burst, causing the raisins to sink. The process of lift-and-sink may repeat several times.

To read John Cowens' related article "Soda Bottle Science" click here.


John Cowens teaches sixth grade at Fleming Middle School in Grants Pass, OR.


Science