Alka Seltzer Rocket – Science Experiment

We’ve been meandering through Apologia’s Exploring Creation With Astronomy for a few months now. While reading the chapter on Saturn, we found an experiment demonstrating how a chemical reaction can launch a rocket. It looked fun, so we thought we’d try it!

Our first launch was immediately intercepted by the puppy and she mangled half of the rocket before we could get to her. That was okay though – the newly refurbished, and shorter, second design actually worked better!

The materials needed for this experiment are:

a plastic film canister (the type whose lid fits INSIDE the canister, rather than snaps on the outside of the rim)

Alka Seltzer Tablet

Warm Water

Paper, tape, scissors, crayons to make your ‘rocket’

Roll paper around the film canister. Make sure the canister is upside down at the bottom of the roll and that the lid can fit on and off easily.

Cut out a circle of paper for the top of the rocket. Cut 1/4 of the circle out (a triangle shape) so that it can fold into a cone. Tape to the top of your rocket. Cut three triangles out of paper and tape to the bottom of the rocket. Decorate any of these pieces as you wish with crayons, markers, etc.

Name your rocket, if you wish. Ours was called: “The Chicken Blaster!”

Turn the rocket upside down, put some warm water in the canister, drop the Alka Seltzer tablet in, replace the lid and QUICKLY set the rocket down (right side up) while moving away from it. We found the highest height & best result was achieved when we used 1 teaspoon of water and 1/2 of an Alka Seltzer tablet, but experiment yourselves to see what happens when you adjust the ratios.

I had to relinquish my camera to get this shot and this is the best we could get. But, at least you can see it flying through the air!

So, what’s the science behind this? Alka Seltzer contains both sodium bicarbonate (baking soda) and citric acid. When dropped in water, the acid reacts with the soda and produces carbon dioxide which keeps building up and building up and building up! until the pressure forces the lid off, sending the rocket flying through the air in the opposite direction. (A good time to talk about Newton’s Third Law!)

Use the usual precautions when dealing with science experiments that deal with explosive force, make sure an adult supervises, and have fun with this!