Toothpaste collage

My daughter and I love to poke around the Intertubes for fun kitchen sink science experiments, and there’s one that’s always caught our attention.

It’s called Elephant Toothpaste because the end product is supposed to resemble toothpaste being squeezed out of a tube. But not just any toothpaste. Huge toothpaste — a big, oozy gush of foamy paste big enough for, say, an elephant. Hence the name.

To do this experiment, you need hydrogen peroxide. You may have some floating around your medicine cabinet.

But there’s a catch.

To really see some big results, you need a solution of hydrogen peroxide not ordinarily found in drug stores or supermarkets. In fact, you’ll probably have to go to the beauty supply store to get the hydrogen peroxide you need — 6 percent, instead of the 3 percent you can find in any store.

But who wants to do that?

I dislike special trips and extra purchases for experiments, because you can usually find what you need around the house to have cheap, easy, learning-experience fun with the kiddos.

I told my daughter Emme, a 7-year-old second grader and lover of all messy science things, about the special ingredients list, and she immediately questioned it. Suddenly we found ourselves at the kitchen counter, trying to determine whether, in fact, you could pull this off and get amazing results with the run-of-the-mill 3 percent solution you can find anywhere.

“We’ll just use bottles with long, narrow necks to give the foam fewer escape routes and force it more powerfully out of the bottle!” my daughter said.

How could I resist that? When your little scientist wants to prove or disprove science experiment, roll with it.

Here’s What You Need

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Here’s What You Do

The set up is pretty easy. Mix your yeast with about 3 tablespoons of warm water and let it sit while you then add a half cup of hydrogen peroxide to your bottle, followed by any food coloring you’d like and a healthy dose of dish soap.

When ready, use your funnel to add the yeast mix to the bottle and then quickly remove the funnel and stand back.

It’s really not too difficult. In fact, the kids can pull this off all on their own. By all means, use safety goggles and gloves if you’d like, but we never encountered a crazy eruption during the process — even with higher volume hydrogen peroxide.

Here’s Why It Works

You know what the molecular structure of good ol’ fashion water looks like, right? H2O? Well hydrogen peroxide is H2O2, or two hydrogen atoms and 2 oxygen atoms. When you add yeast to the mix, the fungi immediately aid in the decomposition of the hydrogen peroxide, stripping off that extra oxygen.

The extra oxygen becomes a gas — all those foam bubbles you see — while the rest is basically water again. The gas starts looking for an escape route and voila! A foamy, toothpasty gush out of your bottle.

Here’s another fun part. The reaction also creates heats, so it’s known as an exothermic reaction. It’s usually not too hot at these concentrations, but you can definitely feel heat emanate off the foam. It’s pretty neat and not too hot, so by all means, mess around with the foam and have fun!

Putting Science to the Test

With our experiments, we basically started out with a big bottle and 3 percent hydrogen peroxide and then started to shrink the size our bottles, hoping a narrower escape route will create a more powerful foamy ooze.

With the biggest bottle, we were … not impressed. Yes, it foamed out but then it just sort of toppled over. Still fun to play with, however!

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With a regular sized glass soda bottle, we saw a neat cascading effect you might find in a chocolate fountain. The foam sort of went everywhere.

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With our smallest bottle, a test tube, the hydrogen peroxide and yeast must not have had a chance to mix well in the smaller container. This was our least impressive attempt, we agreed.

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Finally, looking for some serious paste, I caved and headed to the beauty supply store and bought the 6 percent solution. (The percentages have to do with how much oxygen will be released during decomposition, so the higher the number, the bigger the foam! Beauty supply stores sell it as a hair bleaching agent.)

With this higher volume solution, we definitely saw the results we had seen online and called it a day, but not before splashing food dye onto the ooze for fun.

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Whether you do this one time or try it multiple times with different combinations, it’s a fun, easy science experiment you can take to the next level depending on the demands and inquiries of your little science partner. If you’re anything like us, be sure to carve out some time for some fun tinkering.

More Adventures in Learning

About Mike Adamick

Mike Adamick

Mike Adamick is a stay-at-home dad, writer, inveterate tinkerer, and author of the best selling family craft book, "Dad's Book of Awesome Projects." He writes for the San Francisco Chronicle, New York Times, NPR and many other outlets when he's not sewing his daughter's clothes, woodworking, or training for crazy mud runs. His science book, "The Family Lab," is due in early 2014 and will feature scores of kitchen sink science experiments for the whole family.

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