School Science/Screaming jelly babies
Screaming jelly babies is a chemistry demonstration which is practised in schools all over the United Kingdom. It is often used at open evenings to demonstrate just how much fun secondary school science can be.
This demonstration nicely shows just how much energy there is in a "jelly baby". Potassium chlorate is a very strong oxidizing agent that oxidises the sugar in the jelly baby all at once. The following text gives an explanation of how to perform the experiment. This should only be done by an experienced chemist or chemistry teacher.
Safety
[edit | edit source]- Make sure test tube is completely clean. Any trace of an oxidisable material can cause an explosion.
- Surround the apparatus with safety screens.
- Ensure the pupils/audience are seated several metres away and that they are wearing eye protection.
You will need
[edit | edit source]- Jelly babies
- Large test tubes
- Clamp Stand (retort stand)
- Potassium chlorate
- Tongs
- Access to a fume cupboard
- Bunsen burner
- Safety goggles
- Fire resistant surface
Method
[edit | edit source]1)Put 12-15g potassium chlorate in large test tube. 2)Clamp the tube in a clamp stand at approx. 60° (just off the vertical) then melt the powder with a Bunsen burner. Make sure you are wearing safety goggles. 3)Turn the Bunsen off, then, using tongs and wearing heat resistant gloves stand to the side of your boiling tube, drop in the jelly baby and stand well back.
Results
[edit | edit source]If you follow the instructions above precisely then the jelly baby should burst into flames with a strange, high pitched noise (screaming). There will also be a lot of smoke so open a window. Do NOT touch the boiling tube for at least 5 minutes unless you have protection on.