Teaching IS Rocket Science

You wouldn’t think that a couple of packets of Alka Seltzer, a film canister, and some water would be so much fun. That’s probably because you have never made an Alka Seltzer Rocket. I recently introduced a group of teachers to this simple, but highly addictive science experience. Never heard of Alka Seltzer Rockets?! Here is a very quick explanation. I will leave the experimenting to you!Here is what you will need:

• One Film Canister - I recommend the plastic Fuji Film canisters, but you should experiment with others. Where do you find film canisters in the age of the digital camera? Check you local photo shop or anywhere that develops film. If you mention that you are a science teacher, the person behind the counter will happily give you a bag full of canisters.
• Water - Since rockets are best launched outside, I usually fill a couple of two liter bottles and take them with me.
• 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 (optional) - They make great launch tubes!

Here is how you build a basic 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. Remove one Alka Seltzer tablet from the packet 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 (remember the old commercial…plop, plop, fizz, fizz…oh what a relief it is). 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 and wait…wait…wait…

What happened? Hopefully, your film canister POPPED and launched into the air. If you want to direct the flight of your rocket, try using the paper towel or toilet paper roll. After you have put in the Alka Seltzer and closed the top, drop you canister, top-down, into the roll. Place your hand on the bottom of the roll so that the canister doesn’t fall out. Aim the roll away from you, your friends, and anybody else in the area. Once again…wait…wait…wait. Make sure you have plenty of Alka Seltzer! This is one of those things you have to do more than once. They can be very addictive.

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 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!

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?
• Do some film canisters work better than others?
• Does the rocket work better with different liquids (warning: this can get messy)?

These are just some of the question you may want to answer. There are many, many more. Keep playing with your rockets. You never know what you may discover!