It’s spring – an excellent time for experiments that need some space. That’s why today I have a fun and educational spectacle for you on the balcony and terrace (or inside): The elephant toothpaste!
The well-known experiment shows another important ability ( you can research fermentation here ) that yeast cells and our yeast cells protect themselves from oxidizing agents. And since it creates a lot of gas, you can use this ability for this fun experiment.
You need to
- Yeast: the easiest way to experiment is with dry yeast
- a vessel with a narrow opening: e.g., a 0.5l PET bottle or a test tube
- some warm water (lukewarm, as yeast likes it)
- some dishwashing detergent
- an oxidizing agent: hydrogen peroxide, as a solution (3 – 6%) from the pharmacy/drugstore
- Optional: food coloring
- A funnel that fits on the narrow vessel
- Protective goggles, if necessary, a laboratory coat/painting apron
- A baking sheet or tray as a base
That’s how it’s done
- Stir the dry yeast into the warm water until there are no more lumps.
- Fill the narrow container with hydrogen peroxide (until it is about a fifth (with 6% H 2 O 2 ) or two fifths (with 3% H 2 O 2 ) – use the funnel!) And mix food coloring and one Put in detergent.
- Put the container on the baking sheet.
- Pour the yeast water quickly into the vessel and step back! The reaction starts immediately!
Everything ready: Hydrogen peroxide solution in the test tube on the right (chemists like to use Latinized names of substances – here “Hydrogenii peroxidum,” which can sometimes lead to communication difficulties with shopping chemists) with red food coloring and washing-up liquid. You left a teaspoon of dry yeast in water. Now pour the left into the right, and off you go!
What you can observe
The mixture immediately starts bubbling and foaming violently. The foam oozes out of the vessel opening like a strand of toothpaste and pours out / meanders around on the outside of the baking sheet.
Toothpaste for dwarf elephants: For the sake of one of the chemists’ principles – as much as necessary, as little as possible – I chose the small scale in the test tube. In addition, “my” drugstore only had 3% H 2 O 2 solution in stock – 6% would probably produce even more foam. By the way: A good druggist or pharmacist asks what you intend to do with the solution. Don’t get confused and honest – they’ll give them out!
safety instructions make elephant toothpaste
Even if it often called that: the “elephant toothpaste” is not suitable for brushing your teeth! So could you not put them in your mouth?
Hydrogen peroxide has a corrosive effect on the skin and mucous membranes (the typical white injuries are sometimes only visible after a delay and sometimes only then hurt). If any of the solutions gets on your skin, rinse it off thoroughly with running water. If, despite all caution, something should splash in your eye, rinse your eyes very thoroughly with running water (10 minutes is laboratory standard!) And see an ophthalmologist if you have complaints!
Hydrogen peroxide can also bleach colored textiles. The laboratory coat or the painting apron should protect your clothes from this.
The “toothpaste” itself contains hardly any or no hydrogen peroxide and can therefore be handled safely.
Disposal makes elephant toothpaste.
The “toothpaste” and leftovers in the reaction container can dispose of down the drain with plenty of water. You can store the remaining hydrogen peroxide solution in the tightly closed original container in a dark cupboard and use it later for further experiments.
Protection against oxidation by cleaning up enzymes
When the cells of oxygen-breathing organisms (humans, animals, yeasts, …) obtain energy from oxygen, however, H 2 O 2 can arise in them as an undesirable by-product (as well as the well-thought-out reaction pathways, they are far from running correctly). So that this hydrogen peroxide does not oxidize wildly, the cells have a clean-up command that removes any H 2 O 2 that occurs as a result of errors as quickly as possible.
These enzymes called catalase. These are proteins that accelerate the natural decomposition of hydrogen peroxide. In water and oxygen many times over – by making the reaction much easier.
A biocatalyst facilitates the reaction process make elephant toothpaste
Because reactions are easier when less energy is needed to start them. A substance that can accelerate a reaction (without reacting off itself) by reducing the activation energy required to start the reaction is called a catalyst.
The catalytic converter is a metal surface on which toxic exhaust gases react to formless poisonous substances (you can find more about this here ). In living beings, the catalysts are called enzymes. Enzymes are proteins that facilitate and thus accelerate reactions. The catalases are among the fastest enzymes of all: A single catalase molecule is estimated to convert up to 10 million H 2 O 2 molecules per second! The consequence of this is that the rate at which hydrogen peroxide is broken down with catalase practically only depends on how much H 2 O 2 the enzyme can “grasp” in a given time.
Gas development thanks to catalase
This makes the catalase ideally suited to make hydrogen peroxide. That is produced by errors in other reaction processes that disappear again immediately. Or to release large amounts of oxygen gas in a very short time. From hydrogen peroxide that penetrates from the outside.
If we expose our yeast to (relatively) large amounts of H 2 O 2 by mixing with a hydrogen peroxide solution, these small molecules storm the yeast cells and immediately convert them into water and oxygen gas. If the cells burst or their outer walls broke and oxidized, the catalase comes into direct contact with the hydrogen peroxide solution and the gas create even faster.
Now gaseous substances need many times more space than liquid substances from the identical particles so that the oxygen gas expands very quickly. But since our mixture contains soap, the resulting oxygen portions are enclosed in tiny soap bubbles. Foam creat.
If you look at the “elephant toothpaste” up close, you can see the tiny bubbles.
And this foam, wet from soapy water and yeast cell residues. Oozes out of the vessel as an “elephant toothpaste” snake.
The “elephant toothpaste” consists of foam made of soap and oxygen. Which create by “overfeeding” the oxidation protection enzymes of yeast cells with hydrogen peroxide.
Human cells also have catalases. Which accelerates the breakdown of hydrogen peroxide in the same way: When hydrogen peroxide gets into our skin. Tiny oxygen bubbles develop in the tissue, which we can see as white injuries.
Important: The body’s protective enzymes are precisely designed to remove oxidizing agents created when there are the cell’s own processes. Other oxidizing reaching agents, especially dangerous chlorine compounds sold under the abbreviation “MMS” as “miracle cures,” are omitted! The human body has no protective measures of its own against such substances!
Also read: How to get rid of a yeast infection