Here’s What You Need
- One Film Canister - I recommend the plastic Fuji Film canisters (avoid the black canisters with the gray tops). Where do you find film canisters in the age of the digital camera? Check your local photo shop or anywhere that develops film. They are usually more than willing to share a couple with you.
- Alka Seltzer Tablets - Save some money and go for the store brand. They work just as well as the actual Alka Seltzer brand.
- Safety Glasses - Remember, good science is safe science.
- Paper Towel or Toilet Paper Roll/PVC pipe (optional) - They make great launch tubes!
Here’s What You Do
Let’s start by preparing the materials you will use to launch your rocket. If you are using a launch tube (PVC pipe, toilet paper roll, etc), you will want to cover one end with tape to keep the rocket from falling out. You should also break your Alka Seltzer tablet into fourths. This is usually all you will need to launch your rocket. Of course, you should feel free to explore using more or less Alka Seltzer.
OK…let’s build a rocket. First things first, put on your safety glasses. Now, open the film canister and pour in some water until it is about half full (you may want to experiment with the amount of water you use in the rocket). The next part takes a little coordination. Grab a piece of the Alka Seltzer tablet and drop it into the film canister. Notice anything? Most likely, you will see a lot of tiny bubbles on the surface of the water. Now, quickly put the top back on the canister. Make sure it is on tight and there is no leakage. Place your canister, top-down, on the ground (or in your launch tube). If you are using a launch tube, make sure you point it away from yourself. Now, wait…wait…wait…
What happened? Hopefully, your film canister POPPED and launched into the air. Make sure you have plenty of Alka Seltzer! This is one of those things you have to do more than once. Alka Seltzer rockets can be very addictive.
Now that you have created a basic rocket, here are some things you may want to investigate:
- How high can you get your rocket to fly?
- How far can you get your rocket to fly?
- Can you predict how long it will take, after you put in the Alka Seltzer, for your rocket to launch?
- Does the temperature of the water make a difference in the performance of the rocket?
- Does the rocket work better with different liquids (warning: this can get messy)?
The Science Behind The Rockets
Take a look at the ingredients on the package of Alka-Seltzer. The tiny tablets are made up of citric acid and sodium bicarbonate or baking soda. When you drop Alka Seltzer into water, a chemical reaction takes place between the citric acid and the baking soda react. The result of this reaction is a gas - carbon dioxide. As the gas is produced, it bubbles to the top of the water. That’s where the famous fizz comes from. Usually, when you drop Alka Seltzer into water the gas is released into the air. In the closed film canister, however, the gas has no where to go. As more gas is produced, the pressure inside the canister grows and grows and grows until…POP…the canister is launched into the air!