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Project Summary

Difficulty	1  –  2
Time required	Very Short (a day or less)
Prerequisites	None
Material Availability	Readily available
Cost	Low ($20 - $50)
Safety	No issues

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Sponsor

Sponsored by a generous grant from the Camille and Henry Dreyfus Foundation

Abstract

Objective

In this experiment you will test if adding glycerin or corn syrup will improve a mixture of bubble solution.

Introduction

Everybody loves bubbles! But what makes bubbles form, and float up in the air until they pop?

A soap bubble (Wikipedia Commons, 2006).

The secret to a good bubble is something called surface tension, an invisible bond that holds water molecules together. Water is a polar molecule, so it has plus and minus ends just like magnets that attract each other. When the water molecules align with each other they stick together, creating surface tension.

You might think that it is the surface tension of the water that holds the skin of a bubble together. Actually, the surface tension of water is too strong to make a bubble. You can try yourself to blow a bubble with plain old water, it just won't work! A good bubble solution has a detergent added to it to relax the surface tension of the water, allowing it to have more elastic, stretchy properties. Now it can act more like the skin of a balloon, stretching out nice and thin, trapping air inside of the bubble like a liquid balloon.

What do you need to make a good bubble solution at home? The basic ingredients are water and detergent. In this experiment, you will add glycerin or corn syrup to see if they can help you make better bubbles. Which solution will make the biggest bubbles? Which bubbles will last the longest?

Terms, Concepts and Questions to Start Background Research

To do this type of experiment you should know what the following terms mean. Have an adult help you search the Internet, or take you to your local library to find out more!

• Water molecule
• Polar molecule
• Surface tension
• Physical properties
• Elastic properties
• Detergent

• What are the basic ingredients of a bubble solution and what do they do?
• How do the physical properties of the bubbles change when the ingredients change?
• What mixture makes the best bubble solution?

Bibliography

• Read all about bubbles on this website from the Exploratorium Museum in San Francisco, developed by Exploratorium scientist Ron Hipschman:
  Hipschman, R., 1995. "Bubbles," The Exploratorium Museum, San Francisco, CA. [accessed June 6, 2007] http://www.exploratorium.edu/ronh/bubbles/
• This article explains the components of a bubble formula and the history of bubbles:
  Pepling, R., 2003. "What's That Stuff? Soap Bubbles," Chemical and Engineering News, Volume 81, Number 17, pp. 34, publication of the American Chemical Society (ACS). [accessed June 6, 2007] http://pubs.acs.org/cen/whatstuff/stuff/8117sci3.html
• Read this interesting article about how thin films of water and surface tension are different in space:
  Phillips, T., 2003. "Saturday Morning Science: Elastic Water on the ISS," Science@NASA, Marshal Space Flight Center, National Aeronautics and Space Administration (NASA). [accessed June 6, 2007] http://science.nasa.gov/headlines/y2003/25feb_nosoap.htm
• Here is more information about soap bubbles from Wikipedia:
  Wikipedia contributors, "Soap bubble," Wikipedia, The Free Encyclopedia. [accessed June 6, 2007] http://en.wikipedia.org/w/index.php?title=Soap_bubble&oldid=138169585

Materials and Equipment

• Glass mason jars with lids (recycled jars work great)
• Measuring cups and spoons
• Distilled Water
• Liquid dishwashing soap (e.g. Dawn®)
• Glycerin, small bottle (available at a drugstore or pharmacy)
• Light corn syrup
• Pipe cleaners
• Permanent marker
• Stopwatch

Experimental Procedure

1. First, make your bubble solutions, and store them in clearly labeled glass mason jars. Use one jar for each different solution and label with the formula using a permanent marker. Here are three basic solutions to try, but notice that the total volume of the solution is kept consistent:

   Ingredient	Solution #1 detergent only	Solution #2 detergent + glycerin	Solution #3 detergent + corn syrup
   Water	1 cup (240 mL) + 1 Tbsp (15 mL)	1 cup (240 mL)	1 cup (240 mL)
   Detergent	2 Tbsp (30 mL)	2 Tbsp (30 mL)	2 Tbsp (30 mL)
   Glycerin	-----	1 Tbsp (15 mL)	-----
   Corn Syrup	-----	-----	1 Tbsp (15 mL)

2. Now make a pipe cleaner wand for each solution. Pinch a pipe cleaner in the middle and give it a kink. Bend one half of the pipe cleaner into a circle and twist together at the center. Repeat with the other two pipe cleaners, and check that all three circles are the same diameter.
3. Go outside and test your bubble solutions. Blow a bubble and catch it on your wand. Immediately start the stopwatch and time how long the bubble lasts. This will take some practice, so try it out on some extra solution before you start!
4. Repeat the experiment as many times as possible for each solution.
5. Record your data in a data table:

   	Solution #1 - Bubble Time (secs)	Solution #2 - Bubble Time (secs)	Solution #3 - Bubble Time (secs)
   Trial 1
   Trial 2
   . . . . . . .
   Trial 20
   TOTAL
   Average Bubble Time in Seconds

6. For each bubble solution, calculate the average time in seconds that the bubbles lasted. Do this calculation by adding up all of the data for a solution, and dividing by the number of trials for that solution.
7. Make a graph of your data. For each solution, make a bar of the average time in seconds that the bubble lasted.
8. Analyze your data. Which formula worked the best?

Variations

• In this experiment, you investigated the presence or absence of an additive like glycerin or corn syrup. What about the concentration? If you are good at timing bubbles, you can try this experiment using different concentrations of glycerin or corn syrup in your solutions. How little is too little, and how much is too much to add?
• Do bubbles always make a spherical shape? Try twisting pipe cleaners into different shapes, like: stars, squares, and triangles. What shape will the bubbles be?
• What happens when three or more bubbles come together? See if you can design an experiment to test the idea that three or more bubbles will always meet at a 120 degree angle.
• Have you ever tried Magic Bubbles? They are bubbles that resist evaporation, and are so stable that you can even touch them without popping. The secret to this formula is that a polymer (an elastic molecule) has been mixed into the solution which adds to the elastic properties of the bubble while helping to prevent evaporation. Try adding your own secret ingredients to your bubble mix. Does it change the physical properties of the bubble? Here are a few suggestions:
  • A small amount of glue, like white glue or gel glue
  • Different combinations of food coloring
  • Some scented oils

• For more science project ideas in this area of science, see Chemistry Project Ideas.

Credits

Sara Agee, Ph.D., Science Buddies