Try This

Fun with bubbles

Objective
Have fun experimenting with the properties of surface tension.

Age Range
This activity is enjoyed by all ages

Materials

• 1 large clean bucket, pail, or storage bin (3-5 gallon capacity)
• 1 cup liquid dish soap (Lemon Joy or Lemon Dawn recommended)
• 3-4 tablespoons of liquid glycerine (optional, obtain from a pharmacy)
• 10 cups clean, cold tap or distilled water (add more if the air is dry)
• Bubble wand materials (see procedure steps below): string, drinking straws, wire coat hanger, pliers, plastic 6-pack holder (from soda cans/bottles)

In Advance

1. Measure 10 cups of cold water into the bin. Slowly add dish soap.
2. Add the glycerine - in most atmospheres the addition of glycerine makes the bubbles more durable by reducing evaporation.
3. Gently stir. Avoid vigorous movement - you do not want the mixture to foam at the top because this tends to break your bubbles. If you get froth, simply skim it off with your hand.
4. For best results, let your solution sit for 24 hours before use. This will allow the ingredients to fully dissolve in the water. Bubble solution can be stored in an airtight container for several weeks.
   

Procedure

1. Bubble Wand A: Slide 2 straws on a piece of string about 4-5 times longer than one straw. Tie a knot in the ends. Using the straws as "handles" dip the wand into a cookie sheet filled with bubble solution. Fully open the frame then carefully lift it up out of the solution. As you pull it back towards you slowly flip the frame up or down to release the bubble. Practice.
2. Bubble Wand B: Bend a wire coat hanger into a smooth circle. Using pliers, remove the kink near the base of the twisted section that makes the hook. The hook will serve as a handle. Dip the loop into a shallow pan of bubble solution. Wave the wand gently through the air and rotate it to complete the bubble.
3. Bubble Wand C: Drop a 6-pack beverage holder (that clear plastic thing with lots of holes) into the bubble solution. Wave it around in the air to create clusters of smaller bubbles.
4. Bubble Wand D: This wand simply requires your two bare hands. Form a diamond shape by pressing your index fingers and thumbs together. Maintaining this shape, dip your hands into the bubble solution and slowly pull out. The trick is to blow a steady, controlled stream of air into the diamond shaped opening with your hands extended away at your full arms length. To release the bubble from your hands, you have to close the opening by gently sliding your hands over one another.

 

A Word of Caution: Keep soap out of your eyes and
quickly clean up any spills to avoid slips and falls.

Activity Extension

Make 5-gallons of bubble mixture and pour it into a plastic kid's swimming pool. Use a hula-hoop as the wand to encase a child inside a giant tube-shaped bubble. Great for festivals and large-scale public events.

The Science Behind Bubbles

Bubbles form and hold their shape due to surface tension. The easiest way to visualize surface tension is to imaging that any body of water, from the Mediterranean Sea to a spoon full, is covered by a thin elastic skin. You can see this skin most clearly in a dripping faucet. Each drop hangs from the faucet, suspended by its "skin" until its own weight becomes too much and it falls. (Don't take this visualization too seriously though, you can't peel the "skin" off water as you could an orange. The surface of water behaves like skin, but it is not really a skin.

So why is the surface of water different from the bulk of it? The answer is found on the molecular level. Water molecules are made up of two Hydrogen atoms and one Oxygen atom. Every water molecule is electrically balanced, but the three atoms are oriented in such a way that one end of the molecule has a slight positive charge, and the other end has a slight negative charge. As a result, the water molecule is uneven.

Since electrical opposites attract, the result of this slight imbalance causes water molecules to nest together forming a tight group, one molecule's negative end held by the prostitute end of another molecule.

Imagine a swimming pool full of these clinging molecules. Inside the swimming pool, the molecules are oriented randomly since each molecule is surrounded on all sides by other molecules and thus finds itself pulled in all directions equally. But on the surface of the pool, things are different. Those molecules on the surface of the pool are being pulled in all directions except up, because there's nothing above them except air. These molecules form an extremely tightly-knit group, or skin that is technically called surface tension.

But water is not the only ingredient you need in bubble making. Water by itself makes lousy bubbles because it evaporates quickly and its molecules are too thin to stand up to gravity. Soap reduces the water's surface tension just enough to help it overcome gravity.

Tips for Better Bubbles

Bubbles are fascinating, dynamic, and temperamental. The really big bubbles only appear when the environment is right. Big bubbles like little to no wind, high humidity, cool temperatures, and indirect light. The finest bubble days are foggy or overcast. Regardless of what today's weather offers, you can usually find pools of air that are damp, cool, or still enough to make impressive bubbles.

Great bubbles need high humidity conditions to really perform. Pick up a humidity gauge at your local hardware store or consult the weather forecast. You will find that you will get bigger bubbles on days with 65% humidity or higher (90% is optimum, you will find these conditions immediately following a rain shower).

On dry days (50% humidity or lower), look for pockets of humid air near large bodies of water or trees. Trees, bushes, grass, anything with green leaves transpires water vapor into the air.

On hot days, cool your bubbles in the shade of a tree or tall building. The simple act of moving your bubble into a shadow can make an enormous difference. Also try early mornings or late evenings when air tends to be cool and calm (you'll see more colors in your bubble too!) For frosty fun, try it on a day when temperatures drop below 40 degrees Fahrenheit. These frozen bubbles can really hold their shape!

Wind can be a problem to something as fragile as a bubble. Look out the window when you get the bubble urge. If the trees are quiet, you're in luck. Even if they are rustling, you'll still find quiet pockets of air behind buildings or in the woods. And every neighborhood has a courtyard, cu-de-sac, or two where air is magically still, even on a windy day.

Activity Source
The Groundwater Foundation with references from The Unbelievable Bubble Book by John Cassidy, published by Klutz Press.