The main ingredients for the elephant toothpaste is:
– 3% hydrogen peroxide (the stuff you use on skin to prevent infection of minor cuts, scrapes, or burns. You can easily buy this from a nearby beauty supply stores, pharmacies, or hair salons)
– A clean 16 oz plastic soda bottle or water bottle (or you can create the same effect by using a conical flask that can focus the expansion of foam, so it looks way more impressive)
– Dry yeast (this acts as a catalyst for our expansion and can be found in most grocery stores. Another alternative you can use that creates a much more intense effect is potassium iodine)
– Warm water (note that the water should not be too hot, which can readily kill the yeast)
– A spoon to stir the mixture
– A small bowl for the mixture of yeast and warm water
– Dish soap.
– Don’t forget to wear a safety goggle because the unreacted hydrogen peroxide can irritate your skin and eyes.
- First, set the experiment in a sink or outdoors or some places where you won’t mind getting wet foam everywhere.
- Use a funnel or a steady hand to carefully pour ½ cup of hydrogen peroxide liquid into the bottle
- Add about 10 drops of your favourite food colourings into the bottles
- Add about 1 table spoon of liquid dish soap into the bottle and swish the bottle around to mix it
- Now, prepare for the yeast solution in a separate small bowl, combine a packet of dry, activate yeast with a little bit of warm water and mix them together for about 30 seconds.
- So, we have all the needed ingredients prepared. Now, when we started pouring the yeast mixture into the solution, the chemical reaction will occur instantly and produce a large expansion of colourful foam.
Usually, hydrogen peroxide liquid (H2O2) used is a reactive molecular substance that can easily break down, or decompose, into water (H2O) and oxygen (O) when you leave it exposed to the air outside. The chemical equation of this reaction is expressed as:
- 2H2O2 → 2H2O + O2 (g)
However, in this demonstration, we include the yeast which acts as a catalyst for the decomposition to proceed much more rapidly as you can see the foam rises almost instantly when you start pouring the yeast into the solution.
The reason why dishwashing detergent is the key ingredient for the elephant’s toothpastes is because it creates a foamy effect as the solution rises. This is resulted from the released oxygen gets captured by the soap that makes lots and lots of foam and bubbles.
In addition to being a great demo of a decomposition reaction, this experiment also indicates a reaction called ‘Exothermic Reaction’, which is the process releasing heat. You should notice when the expansion of foam starts proceeding, the bottle gets warm, but not hot enough to cause burn.
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