Alka Seltzer Boom!

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Materials Needed:

  • One film canister (white ones work best)
  • One alka seltzer tablet
  • An area with a high ceiling (or just go outside!)



  1. Fill the film canister half way up with water
  2. Place tablet into the film canister and quickly seal it with the lid
  3. Flip the film canister upside down and step back! Safety tip: point it AWAY from you.
  4. Observe how the film canister shoots off the lid and flies into the air!


How Does it Work?

The molecules in a gas are very spread out and need a lot of space to move around so when a gas is created inside a sealed container, pressure is created due to the gas expanding and needed more space. The film canister can’t expand and give the gas more space so the weakest point (the lid) will be forced to open which results in the rocket-like boom!