Shoot a Projectile Using a Chemical Reaction

Prompt

How far can you shoot a projectile using a chemical reaction? Build a system that shoots some object (ie a cork, ping pong ball, bottle rocket) powered solely by a chemical reaction. Have the students showcase their devices and whoever shoots the projectile highest wins. Examples of chemical reactions include Mentos and Diet Coke, baking soda and vinegar, and heating isopropyl alcohol in an enclosed bottle. The students should describe in writing or during a presentation the science behind the chemistry powering their device, how they built their system, and why they did what they did.

Authors: Rose Solow and Orian Sneor

Final Design

We built a baking soda and vinegar bottle rocket using a plastic soda bottle as the body of the rocket, a cork as the stopper, and pencils to keep it standing. We duct taped three pencils to the outside of the bottle to give it upright stability. We poured vinegar into the bottle and then added a packet of baking soda. Next, we inserted a cork into the mouth of the bottle, shook it up, and placed the rocket on the ground. The vinegar and baking soda reaction produced a build up of gas pressure which propulsed the bottle rocket when that gas escaped.

Big Idea

 The goal of this project is to engage students in chemistry. We hope to do this by:

  • Making chemistry interesting and exciting
  • Involving students in a goal-based engineering project

To complete this project, students must be able to:

  • Understand and explain expanding chemical reactions
  • Imagine, plan, and build a device that makes use of chemistry to launch something in the air
  • Work in groups
Ask

When we were coming up with a design prompt for chemistry, we knew we wanted a project where the students would have to build some kind of device and incorporate their chemistry knowledge into the building of that device. We started with the question, what did we find most exciting about chemistry? The classroom experiments we enjoyed the most when we learned chemistry were examples of chemical reactions. Seeing chemicals react was the best way for us to understand their processes. The most fun chemical reactions for students to watch are reactions involving a significant change, such as rapid color change, expansion, or explosion. Along these lines, we decided that we could have the students use a chemical reaction to propel some object into the air. The students could choose which object to shoot, and how. Students could shoot a small projectile (such as a cork or a small ball) or they could choose to project their entire device (such as a bottle rocket). 

Key questions:

What is the best chemical reaction to propel our object?
What kind of object do we shoot?
What kind of device do we build?

Brainstorm
Plan
Create and Test the Coke and Mentos Device
The Reaction of Coke and Mentos
Create the Baking Soda and Vinegar Bottle Rocket
Test Baking Soda and Vinegar Bottle Rocket Launch

Launching the bottle rocket at first proved difficult. We had problems with the baking soda packet releasing the soda to allow for the reaction to take place. Unfortunately, our efforts did not go as planned. We tried over and over again, but either the baking soda reacted to quickly and the cork would not go in, or the baking soda reacted too slowly and then all at once and the rocket blew up in our hands. Finally, on the fifth try, it worked. We decided that white paper was too thick and we then used a napkin. We still had to shake the bottle a little before launch. 

The Chemical Reaction of Baking Soda and Vinegar
Improve

We tested both devices, and the baking soda and vinegar bottle rocket was much more successful than the Coke and Mentos device. We believe that the Coke and Mentos device would be vastly improved if we used a 2 L bottle rather than a 16 oz bottle to increase the amount of carbon dioxide in the interaction, and did not make a slit in the neck of the bottle, which let a lot of pressure escape. The bottle rocket worked successfully, but we had to go through a few iterations of paper packet choices (thinner rather than thicker paper) for the baking soda before it was completely successful.

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