Pop rocket

Science concepts

Mixing vinegar and bicarbonate of soda produces carbon dioxide gas.
A push in one direction can make something move in the opposite direction.

Special instructions

3–2–1– BLASTOFF! With a simple chemical reaction you can build your own rocket.

Teachers should conduct their own risk assessment of this activity.

Class time required: 45 minutes

Materials

• Plastic cup
• Teaspoon
• Bicarbonate of soda
• Water
• Film canister
• Vinegar
• Decorations (e.g. coloured paper, cellophane)

What to do

1. Place one teaspoon of bicarbonate of soda in the plastic cup. Add a few drops of water and mix to form a thick paste.
2. Put some of the paste inside the lid of the film canister and pack the paste in tightly.
3. Pour a small amount of vinegar into the film canister so it is about one-third full.
4. Carry the lid and canister separately to an open space (outdoors is best as this experiment is messy).
5. The next part has to be done carefully and quickly:
   ........Hold the canister in one hand away from your body and use your other hand to put the lid on.
6. Quickly place the canister upside down on level ground and stand back!
   How high does the film canister fly?
   Where does the energy come from to make the canister move?
7. Clean and dry the film canister.
8. Decorate the canister to turn it into a rocket and then try the experiment again.

What’s happening?

Mixing vinegar and bicarbonate of soda starts a chemical reaction which produces carbon dioxide gas. The gas expands but the film canister has a fixed volume. Pressure builds up until the lid isn’t strong enough to hold the gas inside the canister.

When the canister bursts open, the gas is pushing in all directions, up and down and to the sides. The lid is pushed down onto the ground and the canister is pushed up by the gas, making it fly into the air!