Launching Rockets with Fizz

I don’t think that I can say ‘Rockets aren’t cool’. I know all the words on their own but in that order, they just make no sense to me. This experiment is one of my ‘go to’ experiments to have on any table for a science show because even if you’ve seen them launched a hundred times it’s still exciting waiting for the ‘pop’.

What you’ll need

  • A container with a ‘push on’ lid like a film canister or a bottle with a cork
  • Something that will produce gas – fizzy tablets or sodium bicarbonate (baking soda)
  • Vinegar (the distilled stuff is cheaper and works just fine!)
  • Water
  • Be prepared for some splashes of liquid as the rocket launches!

How to set things up

The general idea here is to put your “fizz-maker” into a container, pour in your vinegar and get the lid on as fast as possible. I wish that I could tell you a foolproof recipe for any container but unfortunately the precise amounts of each ingredient depend on how big your container is, how tightly your lid clips on and how much gas your fizzy tablets make!

Tips and Tricks

  • With just a cork in the top of a bottle this size, you need to check what’s above the bottle! The cork here hit our ceiling which is 3 m high – something to bear in mind!
  • If you add too much vinegar then it can foam out of the top before you can get the cork on!
  • The fastest launch will happen when you use bicarbonate of soda (remember that increase in surface area means a faster rate of reaction, friends!) but the tablets are much easier to work with. I’ve found that fizzy vitamin tablets don’t work quite as well as other fizzy tablets – perhaps because of the extra flavouring added to them which might make the mix quite goopy – but if you can get them into the flask then they will still work! I just had a nightmare with them getting stuck in the neck of the flask.
  • I like to use a glass bottle with a rubber bung in the top. The bottles I use came from Home Sense as a pack of ‘assorted bottles’ – they look interesting and actually work really well! They came with corks made of… well, cork – and these worked out okay but the real winner was buying some rubber bungs. The rubber makes for a better seal and makes the launch a bit more reliable.
  • A classic container for this experiment is just to use a film canister but, admittedly, these are becoming more and more rare these days so amongst people who do Science Shows, film canisters are the treasure they would save from a house fire.

Let’s see it in action

This bottle is about 100 mL in total and I’ve found that half a teaspoon of bicarbonate of soda and 10 mL of vinegar works best for this size.

Pour in the bicarb, pour the vinegar in and quickly get the cork in nice and tight…. then wait….

And Boom!

The cork flew totally out of shot from one frame to the next in this video, so it’s really quick!

So for my friends with low ceilings who want to stop a cork knocking the light out of the sockets, one tip is to make the cork a bit heavier. You could do this with plasticine or by making a rocket out of paper.

I used some copper wire to attach the rocket in this video to the cork. The rocket was launched about a metre and a half into the air.

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