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Burnt to a custard

11 March 2020

Apple pie and custard. Bread pudding and custard. Bunsen burner and custard.

Don’t worry, our Dining Hall menu hasn’t been printed incorrectly! Instead pupils at our popular after-school science club have been creating custard powder fireballs, all in the name of science.

Our intrepid scientists were investigating how the surface area of fuel affects the way that fuel – in this case, custard powder - burns. After connecting a hosepipe to a custard powder filled funnel, our pupils then held their funnel next to a Bunsen burner flame. Keeping well back, and protected by safety goggles, they blew hard into the end of the hosepipe. As the custard powder was blown through the flame, it created an impressive fireball!

Custard powder burns rapidly as it has a high total surface area to volume ratio, which allows oxygen in the air to come into contact with the fuel (custard powder) easily. In contrast, a lump of wood would burn slowly, since oxygen can only touch the outside of the wood. However, if you were to turn that lump of wood into sawdust, that would increase the surface area of the fuel and mean the sawdust would burn quicker, almost like the custard powder.

As our pictures show, our young scientists were using Bird’s Instant Custard Powder, although other brands are available! This experiment should only be done in a science lab, under adult supervision. Our KS3 Science Club meets after-school every Tuesday and new members are always welcome.

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