# Improving Elephant Toothpaste experiment

we are trying to perform the Elephant Toothpaste experiment involving the reaction of yeast and Hydrogen Peroxide for the students at school.

However, the results have been very underwhelming, likely because we have to use the 3% version of Hydrogen Peroxide.

My question is: What are some other ways to help create a stronger propulsion or thicker foam?

Some things I have been experimenting with are reducing the water mixed with the yeast, and swirling the bottle to mix the yeast and Hydrogen Peroxide. Any advice is much appreciated.

• You might try horseradish as a catalyst, rather than yeast. Use the fresh root, not the prepared sauce, and test a few different plants - some are more effective than others.
• Cosmetic supply stores stock 6% (20 volume) $\ce{H2O2}$, but that concentration is more likely to cause skin irritation or bleach fabrics.
• The most effective catalyst for decomposing $\ce{H2O2}$ that I've used is potassium permanganate, $\ce{KMnO4}$, but it has a few liabilities:
• It's a strong oxidant and can start a fire when mixed with organic chemicals.
• It stains skin and fabric anything from pinkish-purple to black. The stain can be removed with sodium bisulfite, $\ce{NaHSO3}$, sold as an iron-stain remover. That can be a fun demonstration but is not suitable for young students to use.

I spent a considerable amount of effort improving this demonstration and ended up with this (10 sec. video).

The best result I found was from the following:

1. Concentrate store-bought 3% $\ce{H2O2}$ to ~30% $\ce{H2O2}$ (or buy the food-grade 30-35% online). Meticulous method is here (6m video).
2. Make a solution of 1:1 $\ce{KI:H2O}$ by mass, e.g. 50g of each.
3. Add some dish soap and food coloring to a large Erlenmeyer flask, then add 100 mL of the 30% $\ce{H2O2}$ solution.
4. Add the 50g/50g solution of $\ce{KI}$ in water.

$\ce{KI}$ is easily purchased online. If you want more of a "toothpaste" effect than the "snowy" effect in the above video, mix the soap/food-coloring/$\ce{H2O2}$ thoroughly before adding $\ce{KI}$.

Safety notes: KI is mostly harmless -- but as in all cases, completely avoid contact with eyes/skin. The iodide will dye your skin brown-yellow (like the hospital stuff used for disinfecting the skin). Concentrated $\ce{H2O2}$ can be very nasty and oxidize your skin, turning it white for a few hours. So use gloves and goggles in all cases. The clean-up for the above video wasn't bad at all but we tossed the towels used to do it.