Mimic a volcano eruption with household chemicals?

Question

How can one mimic a volcano eruption using household chemicals safely?

We've tried it in a testing tube with baking soda and vinegar. This wasn't quite as impressive as expected.

On the web we've found recipes that add food coloring (red) and dish washing liquid to the mix. I guess the latter is for some bubbling effect.

What we have:

• A volcano made from paper-mâché (classic volcano cone form, perhaps a bit steeper than natural)
• Center hole big enough to fit a 1.5 liter water bottle

Note: this is supposed to be done with kids, so please don't propose any method that would generate poisonous fumes or similar.

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Meanwhile tried a soda ($\ce{NaCO_3}$, i.e. not baking soda $\ce{NaHCO_3}$) solution poured into a dish washing solution, then adding a citric acid solution. It was pretty good, but a bit too quick. Vinegar seems to work better than citric acid, too. Also I used warm water to dissolve the reagents.

Answer 1

The 'elephant's toothpaste' experiment with hydrogen peroxide decomposition works well to produce large amounts of foam and might be suitable for what you are looking for. Low concentration hydrogen peroxide solutions are readily available and not dangerous provided you don't get it in your eyes or drink it or anything silly.

Fill the bottle with some hydrogen peroxide solution, add a few drops of orange food colouring and some dish washing liquid and then add something to catalyse the decomposition. You could use something like potassium iodide or manganese dioxide to give you a very rapid decomposition but if you want a slightly less violent and more sustained reaction then apparently dried yeast dissolved in warm water works quite well (yeast contains good amounts of catalase, an enzyme which catalyses the decomposition of hydrogen peroxide).

Having never done this experiment, I can't tell you exactly what quantities to use so you should probably test it before doing it as a demonstration. However, there are some descriptions of the experiment on the internet to give you a good starting point.

http://www.sciencebob.com/experiments/toothpaste.php http://www.stevespanglerscience.com/lab/experiments/elephants-toothpaste

Answer 2

Safety is a critical issue here, and it is very possible to simulate eruption safely, with a simple combination of household items.

A couple that I have seen and tried with some of my younger relatives - quite surprising some of them:

Ketchup and Baking Soda Volcano, this takes a bit of trial and error to get the consistency right. Mix some detergent and water with the ketchup - then react it with baking soda. (Be sure to read the ingredients list on the ketchup first). The reason the eruption occurs is due to:

The ketchup contains vinegar, which is dilute acetic acid. The acetic acid reacts with the baking soda to produce carbon dioxide gas. The gas bubbles expand and rise through the liquid, bubbling out the ketchup.

We also tried adding vinegar (acetic acid) to ketchup for an eruption. Once again, trial and error is needed to get the best consistency required.

The classic Mentos in Coca Cola is a good one as well, but can be too fast and messy (use diet coke to avoid sticky residue). This may or may not be viable due to its lack of viscosity.