“Elephant Toothpaste” Awesome Chemistry Demo: “Elephant Toothpaste” This is a great chemistry demo to use to spark students’ interest and grab their attention. It is called “Elephant Toothpaste” only because of the appearance and should not be used on your elephant!* Although you may want to wait to tell students this until the end of the demonstration so that they can appreciate why it is called “Elephant Toothpaste”. I have used this every year with Science 10 students and they love it! *IT IS NOT EDIBLE WHATSOEVER!!

Supplies needed: RED and GREEN food coloring Regular dish soap 30% Hydrogen Peroxide (H2O2) Potassium Iodide NOTE: 30% hydrogen peroxide and potassium iodide can be purchased through a chemistry supply distributor such as Boreal Northwest http://www.boreal.com/hydrogen-peroxide/p/IG0015288/ http://www.boreal.com/potassium-iodide/p/IG0015475/

Equipment needed: Graduated cylinder (500 mL)* Large pan or container Small beaker (250 mL) Scoopula Goggles Lab coat or apron Rubber gloves *If you do not have a large graduated cylinder, a large Erlenmeyer flask (1 L) will work just as well. The large pan or container is simply to collect the mess. Alternatively you could spread some paper or plastic over the work surface.

Safety Considerations Goggles, lab coat/apron, and rubber gloves must be worn because: H2O2 can bleach skin/clothing. H2O2 may cause burns to eyes/skin. Iodine leaves stains. LEAVE GLOVES ON FOR CLEAN UP! It is important to remember that this is 30% H2O2 is a very strong oxidizer and is much stronger than the 3% Hydrogen Peroxide that you buy at the drugstore.

Procedure Measure out approximately 20 mL of Hydrogen Peroxide (H2O2) using the small beaker. Pour it into the large graduated cylinder. Squeeze a reasonable amount of dish soap into the cylinder and swirl to mix. Drizzle a few drops of RED food coloring down the inside wall of the cylinder, and GREEN down the inside wall opposite it. The measurements for this demonstration do not have to be exactly precise, but keep in mind that larger quantities produce larger messes! The amount of dish soap that you would use for a sink full of dishes would be an appropriate amount. The purpose of the dish soap is simply to trap the oxygen produced during the reaction to make it visible. The food coloring is simply for effect…to make it look more like toothpaste!

The Fun Part! Make sure the large graduated cylinder is sitting in the pan, or on a flat, washable and stain resistant counter. Use the scoopula to take out a heaping scoopful of Potassium Iodide. Quickly add the Potassium Iodide to the prepared graduated cylinder and stand back! If this is your first time doing this demonstration, you may want to measure out the Potassium Iodide so you know approximately how much you should be using. Use a scale and measure out 5 grams. This should be a sufficient amount. It is also recommended that you watch this video: http://www.youtube.com/watch?v=tnB-uU3w6g8 The above link will take you to a video that will show you what to expect, particularly in a high school chemistry lab setting.

“Elephant Toothpaste”! What just happened? Hydrogen peroxide naturally breaks down into water and oxygen. The potassium iodide simply acts as a catalyst making the reaction occur much more quickly! The soap simply traps the oxygen being released. The bubbly mess shoots out of the cylinder very quickly and looks like a large tube of toothpaste, hence the name: You have got to try it! It is really fun! “Elephant Toothpaste”!

Teaching Points This is an exothermic reaction. H2O2 naturally breaks down into water (H2O) and O2 overtime. KI acts as a catalyst. This is an example of a decomposition reaction. Chemical equations must be balanced. There are many topics you could discuss using this demonstration. I often talk about all of the above terms at the beginning of the unit, even though the students do not have knowledge of many of them, and at the end of the unit we revisit this demonstration and they realize how many terms and concepts they have learned! It is assumed that you (the reader) are familiar with the concepts listed. These are just a small selection of examples. Even if you are not a chemistry teacher, you could use this demonstration to get students asking questions and to inspire some inquiry based learning.

More Teaching Points! The Law of Conservation of Mass can be explained using the balanced equation: 2H2O2 = 2H2O + O2 Naming of ionic compounds and covalent (molecular) compounds. The occurrence of diatomic elements is illustrated in O2. There is certainly many concepts to explore with Science/Chemistry students using this demonstration…or it is simply a fun, random demonstration that the students will love! It really never gets old. My students frequently ask if we can do it again! Have fun and remember to follow the safety considerations!