Floating soap bubbles
The materials required for this science fair project:
- 2 empty aquariums
- 100 grams of soap powder
- 1 liter of water
- bubble blowing toy
- small plastic container to mix the soap powder with water
- 200 ml of vinegar
- 100 ml of sodium bicarbonate
- 1 glass bowl
- 1 stopwatch
1. For this experiment, the independent variable is the air density (amount of carbon dioxide) in the aquarium. The dependent variable is the length of time the soap bubble stays afloat. This is determined by recording the time using a stop watch. The constants (control variables) are the volume of the tank, the soap water mixture and the size of the bubbles.
2. The 2 water tanks are labeled as “carbon dioxide” and “air”. Both tanks are placed overturned on a flat table.
3. The 200 ml of vinegar and 100 ml of sodium bicarbonate is mixed in the glass bowl. The mixture will fizzle and produce carbon dioxide. The bowl is immediately placed under the tank labeled carbon dioxide until the chemical reaction stops. The tank labeled “carbon dioxide” is now filled with carbon dioxide.
4. The soap and water is mixed in the plastic container. Using the bubble blowing toy, practise blowing a few bubbles first.
5. Gently blow 5 bubbles into the tank labeled “carbon dioxide”. Record the time for all 5 bubbles to drop and touch the table surface. Repeat the test 5 times to obtain the average time. Record the readings in the table given below.
6. Similarly blow 5 bubbles into the tank labeled “air” and record the time for the bubbles to touch the table surface. Repeat the test 5 times and record the readings in the table below.
Handle the glass tanks carefully.