Blowing the Best Bubbles
IntroductionIf you have ever tried to make bubbles using plain water, you may have seen that it does not work. This is because the surface tension of water is too high. When detergent is added to water, it lowers the surface tension so that bubbles can form. Other things can be added to this mixture, such as corn syrup or glycerin, to make a solution that is even better for creating bubbles. In this science activity, you will find out which solution creates the best bubbles!
- Permanent marker
- Masking tape
- Pipe cleaners (3)
- Large cups or jars with a wide opening (3)
- Measuring cups
- Tablespoon measurers
- Liquid dishwashing soap, e.g. Dawn or Joy
- Distilled water. This is available at grocery stores.
- Glycerin (small bottle). This is available at a drugstore or pharmacy.
- Light corn syrup
- Make a pipe cleaner wand by pinching a pipe cleaner in the middle and bending half of it into a circle, twisting a little bit of the end to secure it. Make two more pipe cleaner wands this way, making sure their diameters are all the same.
- Take three cups and label them "Detergent Only," "Glycerin," and "Corn Syrup" using the permanent marker and masking tape.
- To all three cups add 1 cup of water and 2 tablespoons (Tbsp.) of detergent. To the "Detergent Only" cup add an extra 1 tbsp. of water.
- Mix the detergent in each cup. You should see small bubbles forming as you mix in the detergent.Why do you think you need detergent in every solution?
- To the "Glycerin" cup add 1 tbsp. of glycerin and to the "Corn Syrup" cup add 1 tbsp. of corn syrup. Mix the "Glycerin" and "Corn Syrup" cups.What is the consistency of the glycerin and corn syrup? Does one seem more viscous (thick and sticky) than the other, or do they have about the same viscosity?
- Go outside and blow a bubble from one of the solutions. Try to catch the bubble on your wand and time how long the bubble lasts before it pops. This can be difficult to do, so you may need to practice this first. Also, it may be helpful to have another person time you.
- Catch and time at least four bubbles from each solution.Which solution makes bubbles that last the longest? Which solution makes the shortest lived bubbles? Why do you think this is?
What Happened?Detergent lowers the surface tension of water enough so that bubbles can form. The solution with only water and detergent probably made smaller, shorter-lived bubbles overall compared to the solutions with glycerin or corn syrup. When the water in a bubble evaporates, the bubble pops. Glycerin and corn syrup form bonds with the water and this makes the bubbles take longer to evaporate, which improves the lifespan and durability of the bubble. Glycerin makes stronger, longer-lasting bubbles, but corn syrup is often substituted in bubble solutions because it is less expensive.
In a container of water, the tiny water molecules are attracted to each other, and consequently they are always pulling on each other. At the surface of the water these water molecules are attracted to the water molecules around and below them, but have no water molecules above them to be attracted to (since it is just air). This is what creates surface tension. The water molecules at the surface of the water do not want to move up, away from other water molecules, which makes water have a high surface tension. In fact, it is too high to form bubbles.
When detergent is added to water, it lowers the surface tension so that bubbles can form. The detergent molecules increase the distance between water molecules and reduce the water molecules' ability to interact with other water molecules. This reduces the pull that the water molecules exert on each other and lowers the surface tension of the solution. A bubble formed from a solution with water and detergent is a spherical layer of water molecules that is surrounded on either side by a layer of detergent molecules. Parts of the detergent molecules are attracted to water (they are hydrophilic) and other parts do not want to be near water (they are hydrophobic). Consequently, the detergent molecules in the bubble become oriented so that their hydrophilic parts touch the water and their hydrophobic parts face outward, touching the air.
Ask an Expert
For Further Exploration
- How does the concentration of glycerin or corn syrup in the bubble solution change how long the bubbles last? You can try this activity again but using different concentrations of glycerin or corn syrup in the solutions. How little is too little, and how much is too much to add? Can you make a bubble solution that results in bubbles that last longer than the ones in the original activity?
- Do bubbles always make a spherical shape? Try twisting pipe cleaners into different shapes, such as stars, squares, or triangles. What shape are the bubbles made from these differently shaped pipe cleaner wands?