IS IT BOLLOCKS?

Film Buff investigates the facts behind outlandish movie plots.

Can you make gummy bears go boom or what?

Q In Logan Lucky, Daniel Craig’s Joe Bang creates an explosion using bleach pens, salt substitute and gummy bears twisted in a plastic bag. Big bang theory or bollocks?

A

PROFESSOR MARK LORCH

DEPARTMENT OF CHEMISTRY, UNIVERSITY OF HULL

The reaction used by Joe in Logan Lucky is a classic chemistry demo, sometimes known as the ‘Screaming Jelly Baby’. To perform it (and

don’t try this at home) you melt potassium chlorate and drop in your juvenile-shaped confectionery. The chlorate rapidly oxidises the sugar in an intense exothermic reaction, hence the great bit of chemistry theatre. So there’s the first bit of scientific truth in the scene. But Joe doesn’t use potassium chlorate, just bleach and salt substitute. He explains the potassium chloride in the salt combines with the sodium hypochlorite in the bleach to give potassium chlorate. That’s also good chemistry, so Joe gets another big tick from his chemistry teacher. But the reaction needs almost pure potassium chlorate. Bleach is only about 3-6% sodium hypochlorite, and the rest is water, meaning there’s no way Joe could get enough potassium chlorate from the bleach. And there’s an even bigger problem; to get a jelly baby to scream you need to drop it into really hot potassium chlorate. Online, you’ll see folks heating the apparatus with a Bunsen burner. Without the heat, the jelly baby would sit there doing, well, not a lot, and there’s no sign of anything heating up Joe’s bag of bleach, salt substitute and sugar, so I’m afraid the scene is bollocks. In case you’re tempted to prove me wrong, DON’T. Heating up bleach won’t cause an explosion, but it can go wrong in all sorts of other really nasty ways.