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Science LinXScience Experiments

Smother a fire with baking powder

Episode 5

You don’t always need a big laboratory for exciting experiments... Use baking powder and vinegar to do a fun party trick – or commit murder.

As a young man, the chemist Jacobus van ’t Hoff carried out scientific experiments in his living room. He did these experiments in front of paying visitors, and used the money he earned to buy materials, such as pipettes, test tubes, etc., to carry out new experiments. The following sounds a bit like a motivational ad: In 1901, Van ’t Hoff won the first-ever Nobel prize for chemistry. But it does show you where a bit of tinkering about in the living room can get you!

However, tinkering in the living room has been getting more and more difficult recently. There isn’t a publisher left who would dare to burn their fingers (no pun intended) on a good book with interesting experiments, and even if you were to find such a book second-hand (I can recommend Chemistry at Home or The Golden Book of Chemistry Experiments), the chemicals required are nowhere to be found. Try to get hold of potassium ferricyanide (K4Fe(CN)6) for example, an ingredient often used in old chemistry books. I would truly be amazed if anyone could find it.

About the only chemical compound you are likely to find is sodium bicarbonate (NaHCO3), i.e. baking powder. Baking powder is used in cooking to make bread and cakes rise; however, in the Cogito ergo boom! lab the possibilities are endless – you can use baking powder to launch a rocket, isolate DNA, smother a candle or... commit murder.

First a little theory: when baking powder comes into contact with water or, even better, vinegar, a reaction is caused during which carbon dioxide (CO2) is released. Here is a simplified version of the equation for enthusiasts:

NaHCO3 + CH3COOH ->

NaCH3COO + CO2 + H2O

Sodium acetate (in solution) and water are also formed alongside carbon dioxide, but in the following experiment it’s the CO2 we’re interested in. Take a tall lemonade glass, empty a sachet of baking powder into it and carefully pour in a dash of vinegar. Leave the glass to stand while the baking powder and vinegar react. After it has finished fizzing, carefully take the glass and hold it at an angle above another glass, as if you were pouring it out...

which is exactly what you are doing! There is a layer of CO2, a gas which is heavier than air, above the liquid in the glass. When you hold the glass at an angle, the heavier CO2 pours into the second glass. And how do you know that the second glass contains CO2 and not air? By pouring it out over a burning tealight. The candle is temporarily deprived of oxygen and thus is extinguished.

You would think this would be a fun party trick, but if you scaled it up it could have lethal consequences. With a few kilograms of baking powder and a few buckets of vinegar you could produce enough CO2 to kill your worst enemies in their sleep – when your victims are lying in their beds you only need to fill the lower half of the room with gas. Be warned though; carbon dioxide poisoning is always considered by the coroner during an autopsy, so maybe you should find another way to get the deed done.

In 1986, at Lake Nyos in the north-west of Cameroon, more than 1800 people were killed when CO2 was released from the crater lake as a consequence of volcanic activity. The heavy gas rolled down the side of the volcano and surprised the inhabitants in the surrounding villages like a silent killer. A long vertical pipe has now been placed in the lake to control the release of the carbon dioxide gas. On the internet you can find photos and films of the pipe, spouting a 21 metre high fountain into the air – the world’s biggest Mentos fountain. But Mentos fountains are a subject for a possible future episode, as are baking powder rockets and the isolation of DNA.

Author: Ernst Arbouw

Last modified:11 October 2017 2.43 p.m.
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