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How do Elephants Brush Their Teeth? Ask a chemist.

Look!  My hand made a cameo!

Note: Do not use this to brush your teeth.

Outreach is becoming one of the most important aspects of undergraduate, graduate, and professional chemistry. Reaching out to kids at a young age and helping them get in to chemistry is a priority.  This is also one of the main focuses of the ACS’s International Year of Chemistry (IYC) 2011.

I remember in my first chemistry class when my teacher showed us the classic demo where she turned water to wine, then wine to milk, then the milk to beer. To me and my classmates, it seemed like magic.  It was pretty much the coolest thing since, well, the power rangers.  Or the Offspring.  Anyway, we now have a much different perspective.  These chemistry demonstrations utilize relatively simple chemistry to produce really fun and exciting results.  Does that mean that all the magic is gone?  I don’t think so.  A few weeks ago, I had the chance to do some of these demos to a crowded audience of elementary school kids.  Needless to say, I had a blast.  The kids did too.  Over the next couple weeks, I’m going to be profiling a couple of the demos I did, and how to do them for your friends, neighbors, or chemistry classes.  We all know that chemistry is fun:  other people just need some help remembering.

Today, I’m profiling one of my favorites:  The elephant’s toothpaste.  Here’s how it’s done:

What you need:

  1. One (1) Graduated cylinder, as large as you can find it.  Really, the bigger the better.  I used a 2.o L guy I found lying around in my lab,  but I imagine that doing this with a 4 L or 8 L would make some kid’s day.
  2. 150 mL of dish soap.  Really doesn’t matter what kind
  3. 150 mL 30% Hydrogen Peroxide.  This is dangerous – it’s an irritant and will hurt if you get it on you.  Wear gloves, a lab coat, and goggles.
  4. Food coloring (be very generous)
  5. ~5mL of saturated KI.  I do this by putting a lot of KI into a 50mL falcon tube and adding water.  Then I shake until I’ve dissolved all I can, and add 5mL

This is how it’s done:

  • Put the peroxide, soap, and food coloring (again, be generous)
  • Add some KI
  • Watch it happen

This demo is really fun.  Just don’t forget to lay down some newspaper so cleanup is a easier.  Also, a note about safety:  because of the peroxide, don’t be staring down the tube as you pour the KI in.  First, you’ll get burned by peroxide, then you’ll get majorly stained by KI.  Neither of these things will be enjoyable, I promise.  If you’re prepared correctly and introduced the demo in a fun and interesting way, this should go off great and be a highlight of your chemistry show!  Enjoy!

-Sidechain

P.S:  The recipe above is optimized for a 2 L graduated cylinder.  If you want to use bigger or smaller, scale up or down respectively.

4 Comments

  • May 4th 201118:05
    by B_geoq

    Is this the same experiment Sheldon (The Big Bang Theory) used to prank Kripke for revenge?

  • May 4th 201119:05
    by Sidechain Bob

    One and the same

  • May 6th 201122:05
    by Jay Banks

    How fast does it work? Do you think it is a good trick for the Chemistry classroom?

  • May 7th 201119:05
    by Sidechain Bob

    It works so fast that I would advise moving away from the graduated cylinder pretty much as you pour the KI in. It is a very exciting demonstration and great for a classroom. Just make sure to put newspaper down underneath the demo, or you have quite the cleanup on your hands.

    For an idea of how long it takes, check out this video!

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