5 Activity: Alka-Seltzer Rocket

Supplies per student:

Film canister (can be ordered online)

1 tbsp water

Half tablet Alka-Seltzer tablet (or other brand)

Question: What do you think will happen when we add water to the canister with a tablet inside then put the cap back on?

Directions: Do this outside. Place a half tablet of Alka-Seltzer in the canister and add a small amount of water. Immediately replace the cap and advise the students to quickly set the canister down in a designated and step away. The canister should build up enough gas pressure to pop the cap off. Repeat multiple times with a fresh half tablet and water each time.

Theory:  The water reacts with the baking soda and citric acid in the tablet. This creates water, sodium citrate, and carbon dioxide. The build-up of gas pressure forces the cap off the canister.

Grades: 3rd – 4th grades

Time: 15 minutes

Clean-up: Wash the canisters for reuse.

Notes and Hints:  The caps can be a little tricky to remove and place back on, so it may be challenging for earlier grades. There is an element of danger as well if there are too many students crowding around.

Image Credit: https://www.fizzicseducation.com.au/150-science-experiments/force-movement-experiments/film-canister-rockets/