Alka-Seltzer Rocket | Physics Tricks

An oldie but a goodie – guaranteed to impress audiences of all ages. Turn simple familiar household ingredients into an awesome rocket!


• empty film cannister
• Alka-Seltzer tablet
• water


1. Place the Alka-Seltzer tablet in the film cannister.
2. Add ~1cm of water.
3. Fit the lid on the cannister, making sure the seal is tight.
4. Turn the cannister upside-down and place it on a flat surface. Stand back!

How does it work?

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 cannister this gas is contained within an enclosed space. As more gas is given off the pressure inside the cannister rises until there is enough force to overcome the seal of the lid. The built up pressure exerts enough force to shoot the cannister into the air, forming the rocket.

Tips for Success

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

Serving Suggestions

This is a good demonstration for attracting people from far away as they can see and hear the rocket in action. It can be fairly messy so is either most suited to outside environments OR locations that are easily cleaned! It works with audiences of all ages.

Did You Know?

The Chinese began building chemically powered rockets as long ago as the 1150’s. One of the great pioneers of modern rocketry, N. I. Kibaltchich was executed in 1881 after manufacturing the bomb that was used to assassinate Tsar Alexander II.


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