Scientist takes Mentos and Coke Craze Into Schools

The Coke and Mentos fountain experiment has grabbed worldwide attention, with thousands of people tuning into Eepybird.com (www.eepybird.com) to watch the explosive results of mixing the sweets with the fizzy drink.

Such is the interest in the video – which shows hundreds of large bottles of Diet Coke erupting in sequence – many Internet users have done the experiment themselves, created their own videos and posted them on video sharing site YouTube (www.youtube.com).

Dr Sarah Heath, who is Outreach Director for the School of Chemistry at The University of Manchester, goes into school in the Greater Manchester area to give exciting science demonstrations on solids, liquids and gases.

And after seeing how the video has captured the imagination of children, she is planning to capitalise on this interest and introduce the spectacular foaming fizzy fountain into her repertoire.

She said: “I mentioned to my daughter that I was looking at doing the Mentos and Diet Coke experiment, and she said all her friends at her school had been talking about it.

“I think it’s a great thing because it’s got children interested in science. We can talk about the chemistry that lies behind it later, but the important thing is to capture their attention in the first place.

Dr Heath already demonstrates how to make flat water fizzy by dissolving carbon dioxide into it. She feels the Coke and Mentos fountain fits nicely into her existing presentation, as it shows the gas coming out again.

The visuals are not dissimilar from an experiment she already performs for pupils, where oxygen is released from hydrogen peroxide to produce a spectacular mass of foaming bubbles.

Scientists and chemists have so far put forward various theories on why Diet Coke reacts so violently when Mentos are added, but Dr Heath feels the rough surface of the sweets plays a big part.

“If you drop anything into a fizzy drink you will get bubbles. For example, with ice you get bubbles but they don’t go mad and shoot out of the glass. If you poor a fizzy drink into a dirty glass, bubbles form around what we call nucleation sites. If the glass is cleaner and smoother, it doesn’t fizz as much.

“When you look at a Mento under a microscope you will see that it’s quite pitted and therefore has lots of nucleation sites, which causes the carbon dioxide to be released. There is probably also a chemical reaction occurring but there is a lot of debate about this.”

On the subject of what would happen to someone who drunk Diet Coke and then ate Mentos, Dr Heath says: “When you open a bottle of Coke and drink it, most of the gas escapes so the reaction would not be as violent. But you might find that you burped more than usual.

“I must stress that people should not try this under any circumstances, but if you drunk a lot of Diet Coke and swallowed a whole packet of Mentos without chewing, that could certainly produce an interesting reaction.”

At present Sarah has only been able to find fruit Mentos to recreate the experiment – but has discovered they work just as well.

Teachers interested in Dr Heath’s science demonstrations should email Sarah.L.Heath@manchester.ac.uk.