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Bubblology Experiments

Posted: Sat Jul 26, 2008 7:48 am
by fwizard
Bubblology Experiments
to Share with Your Kids
By Aurora Lipper

This article teaches kids about the science of bubblology and gives a handful of totally fun activities to experiment with for their homeschool science learning (including bubble castles, light shows, and a kid-in-a-bubble). It’s also good for boy scouts working on a badge, or for any kids that love science experiments. These experiments are part of a homeschool science program that I teach, and I promise your kids will love it.

If you pour a few droplets of water onto a sweater or fabric, you'll notice the water will just sit there on the surface in a ball (or oval, if the drop is large enough). If you touch the ball of water with a soapy finger, the ball disappears into the fibers of the fabric! What happened?

Soap makes water "wetter" by breaking down the water's surface tension by about two-thirds. The force that keeps the water droplet in a sphere shape is called surface tension. It's the reason you can fill a cup of water past the brim without it spilling over. Water becomes "wetter" because without soap, it can't get into the fibers of your clothes to get them clean. That's why you need soap in the washing machine.

Soap also makes water stretchy. If you've ever tried making bubbles with your mouth just using spit, you know that you can't get the larger, fist-sized spit-bubbles to form completely and detach to float away in the air. Water by itself has too much surface tension, too many forces holding the molecules together. When you add soap to it, they relax a bit and stretch out. Soap makes water stretch and form into a bubble.

The soap molecule looks a lot like a snake – it's a long chain that has two very different ends. The head of the snake loves water, and the tail end loves dirt. When the soap molecule find a dirt particle, it will wrap its tail around the dirt and hold it there.

To make the best bubbles for teaching homeschool science, you'll first need to make the best bubble solution. Gently mix together 12 cups cold water in a shallow tub with one cup green Dawn (or clear Ivory) dish soap. If it’s a hot dry day, add a few tablespoons of glycerin. (Glycerin can be found at the drug store.) You can add all sorts of things to find the perfect soap solution: lemon juice, corn syrup, maple syrup, glycerin… to name a few. Each will add its own properties to the bubble solution. (When I teach this class, I have buckets of each variation along with plain dish soap and water so we can compare.)

The absolute best time to make gigantic bubbles is on an overcast day, right after it rains. Bubbles have a thin cell wall that evaporates quickly in direct sun, especially on a low-humidity day. The glycerin adds moisture and deters this rapid thinning of the bubble’s cell wall.

Tip for Teaching Homeschool Science: Keep a box handy with these items inside: paper clips (in two different sizes), rubber bands, dish soap (clear Ivory and green or blue Dawn), straws, string, plastic berry baskets, plastic water bottles, and wire coathangers. Label your box “Bubblology Experimentsâ€