Pop Rocket

Ready... set... blast-off! A push in one direction can make something move in the other direction. Use carbon dioxide gas to make a rocket fly!

Australian Curriculum links

  • Science > Chemical Sciences > Year 5 > ACSSU077
  • Science > Chemical Sciences > Year 6 > ACSSU095
  • Science > Chemical Sciences > Year 8 > ACSSU225
  • Science > Chemical Sciences > Year 9 > ACSSU179

You'll need

  • plastic cup
  • teaspoon
  • sodium bicarbonate (baking soda)
  • water
  • film canister
  • vinegar
  • decorations (e.g. coloured paper, cellophane)

Try this

  1. Place one teaspoon of sodium bicarbonate 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, packing 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.

Further investigation

Try this activity using a fizzy tablet such as Berocca or Alka-Seltzer. Fill the canister half way with water then drop half of a tablet inside the canister, push the lid down quickly and stand back. What happens? Why does the lid pop off? Try this activity again with a whole tablet or different amounts of water.

What's happening?

In this activity, mixing the vinegar and sodium bicarbonate starts a chemical reaction which produces carbon dioxide gas. The gas expands quickly and puts pressure on the lid of the film canister. The pressure is so strong that eventually the pressure of the gas pushes the lid off the film canister.

The chemical reaction between sodium bicarbonate and vinegar is an example of an acid-carbonate reaction. The acetic acid in the vinegar reacts with the sodium bicarbonate to produce sodium acetate (a type of salt) and carbonic acid. The carbonic acid is unstable and continues to break down to form carbon dioxide gas and water.

As the reaction progresses, more carbon dioxide gas is released. The film canister has a fixed volume so pressure builds 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!

Real world links

To get into the Earth’s orbit, a space shuttle travels from 0 to 28,163 kilometres per hour in just 8.5 minutes, using almost 2 million litres of super-cold liquid hydrogen and liquid oxygen as fuel! Learn more from the NASA Facts web site.