Alka Seltzer Rockets

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What You Need:

  • Alka-Seltzer-Rocket-edit3Plastic cups
  • Film canisters
  • Water
  • Alka Seltzer pellets
  • Pre-drawn construction paper


What Do You Do?

  • Add either 1/4, 1/2, or 3/4 of the canister with water.
  • Place the Alka-Seltzer tablet in the film canister.
  • Fit the lid on the canister, making sure the seal is tight.
  • Quickly turn the canister upside-down and place it on a flat surface. Stand back!
  • Which canister went the furthest?  1/4, 1/2, or 3/4?
  • Take home the construction paper so that you can now decorate your rocket!

What Happened?

When water is added to the Alka-Seltzer tablet, bubbles of carbon dioxide gas are given off. When the lid is fitted tightly to the canister this gas is contained within an enclosed space. As more gas is given off the pressure inside the canister rises until there is enough force to overcome the seal of the lid. The built up pressure exerts enough force to shoot the canister into the air, forming the rocket.

Tips for Success

Make sure the film canister lid is tightly fitting or you will only get a disappointing ‘fizz’. You should also clean the canister lip and lid between demonstrations so that no pieces of Alka-Seltzer get stuck between them, ruining the seal.

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