Model Tsunami

Cause a tsunami by erupting a canister full of bubbling gas underwater

Suitable for kids aged 10+ with parental supervision

CAUTIONThe canister lid comes off with a lot of force, stand back and be careful to stay right out of its way.

You Need:
  • Empty film canister with tight fitting lid or something similar
  • Plasticine
  • Alka-Seltzer tablet (available from the supermarket)
  • Tub or bucket (preferably transparent)
  • Water
What to do:
  1. Mould enough plasticine around the bottom of the film canister to give it the appearance of a volcano and enough weight to keep it down in the tub of water.
  2. Fill the transparent tub or bucket almost to the top with water.
  3. Fill the canister one third full of water.
  4. Break the Alka-Seltzer into quarters and drop one quarter into the canister of water.
  5. Quickly push the lid onto the canister firmly, then plunge the plasticine-canister into the bucket of water and stick it to the bottom making sure it stays put.
  6. Move back away from the bucket and canister, then wait for the action. After a minute or so the canister lid should fly off causing a tsunami-like wave. If the lid doesnt come off there is a possibility that gas is leaking around the edges of the lid make sure it is a tight fit.
  7. How big is the wave? Did the wave make it out of the bucket onto the table. Experiment with different quantities of water and tablets. Which mixture creates the biggest wave?

Why is it so?

Alka-Seltzer tablets contain citric acid and sodium bicarbonate, when these chemicals are mixed with water a chemical reaction takes place producing a new chemical carbon dioxide gas. The build-up of carbon dioxide gas in the film canister creates enough pressure to force the tight fitting lid off the canister. The resultant underwater disturbance pushes a relatively large volume of water to the surface creating a model tsunami.