Summary

In this project, students will design and build a soda bottle boat with the goal of having the fastest boat to get to the other end of the rain gutter racetrack. Students will have to complete stoichiometric calculations to determine an appropriate amount of “fuel” (baking soda + vinegar) to power their boat.

Grade Level

High School

NGSS Alignment

This project will help prepare your students to meet the performance expectations in the following standards:

• HS-PS3-3: Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy.
• HS-ETS1-2: Design a solution to a complex real-world problem by breaking it down into small, more manageable problems that can be solved through engineering.
• Scientific and Engineering Practices:
  • Using Mathematics and Computational Thinking
  • Constructing Explanations and Designing Solutions

Objectives

By the end of this project, students should be able to:

• Create, test, and refine the design of a soda bottle boat powered by the chemical reaction between baking soda and vinegar.
• Perform stoichiometric calculations and carry out test reactions to determine the appropriate amount of “fuel” (baking soda + vinegar) for their soda bottle boat.

Chemistry Topics

This project supports students’ understanding of:

• Stoichiometry
• Balancing chemical equations

Time

Teacher Preparation: 30-120 minutes (once the rain gutter racetrack is constructed, it can be reused in future years and will significantly cut down on prep time)
Lesson: 120-240 minutes over 2-4 days for calculations, development, and refinements, and 45-60 minutes to race the boats

Materials

Instructor use/construction:

• Two 10-foot rain gutters capped at both ends marked in 1 ft increments
• Waterproof sealant for attaching end caps
• Hardware tools, such as cordless drill or similar, to make modifications to bottles to create a gas outlet to propel boats.

Student boat construction (students may not choose to use all the materials on this list):

• at least one plastic bottle (16-24 oz) with its cap, supplied by students
• baking soda (1 lb. Box)
• vinegar (1 qt Bottle)
• string
• tissue (single-ply toilet paper seems to work best for students that want to encase baking soda)
• scissors
• straws
• pipettes
• other basic craft supplies (anything you might normally find in a classroom)

Optional supplemental materials:

• some type of sealant (fast setting waterproof super glue or hot glue gun)
• weights (such as modeling clay or small rocks)
• other equipment at students’ request, as approved by instructor

Safety

• Always wear safety goggles when handling chemicals in the lab. (There is a large possibility that the reaction mixture will spray out of the bottle at an aggressive rate.)
• Students should wash their hands thoroughly before leaving the lab.
• When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.
• Hardware tools, if used, are either used only by the instructor or with close supervision.
• Verify a gas outlet to prevent severe pressure buildup and possible bottle rupture.
• If students are not actively using the test track, have them move to a clear area so they are not in the way of another group’s tests.
• Students should wear lab coats or lab aprons to prevent reactants from getting on clothes.

Teacher Notes

• This project is a hands-on way to combine chemical reactions, stoichiometry, and engineering practices. Since it will take several days to complete (and should be done outside in reasonably comfortable weather), it could be a fun post-AP exam or end-of-year project. Students should work in teams of 3-5.
• The instructor will need to construct (2) 10-foot rain gutter racetracks with end caps secured with waterproof sealant as testing and competition tracks. Any local hardware store will have the materials. You will want to mark them in 1-ft increments for students to have a measurement of how far boats are traveling if they are not traveling the full 10 ft. For best results with testing and racing, fill gutters halfway with water and try to level out with shims.
• The instructor will need to supply hardware tools, i.e., cordless drill, drill bits, and hot glue gun, for boat modification if students are to modify in class. These should be used by the instructor or with close supervision.
• Due to the high likelihood of the reaction mixture spraying out of the bottle boats, it is strongly recommended that the testing and racing part of this project take place outside.
• Depending on the boat design and the number of reactants used, boats may fly off the track, so be sure to complete this activity in an open area where no one is at the end of the track.
• The gutter tracks should be placed on a fairly level surface so the water level in the gutter tracks is consistent. The surface should also tolerate getting messy, such as a parking lot or a grass field, as the reaction mixture is likely to spray outside of the gutter tracks.
• Make sure tracks are free of debris and materials before each trial or race.
• The boat designs will vary between groups, but should all include a small hole for a gas outlet to both power the boat and prevent the bottle from rupturing. Be sure this is part of students’ design before you approve it.
• Commonly, students’ designs involve putting one reactant into the bottle prior to testing/racing, then as they are given the “go” they add the second reactant (either directly in the mouth of the bottle before putting the cap on, or through a secondary opening they put in the side of the bottle, possibly with a funnel). They then cap or cover the larger opening directing the gas flow through a smaller opening (usually in the cap) which propels the boat in a specific direction down the track. Students tend to get the best results if they can close the cap before any reaction has occurred.
  • Other things students might try include hot-gluing “fins” of some sort to the bottle or using a tissue to encase the baking soda to make it easier to add all at once. (They will likely realize in their trials that the tissue could clog the gas outlet, which would need to be resolved for the final model.)
• You may wish to review the balanced equation of the baking soda and vinegar reaction with students ahead of time, or at least let them know that CO₂ will be one of the products. They may struggle to identify that one of the products, H₂CO₃, decomposes further to produce water and carbon dioxide. The production of the CO₂ gas is what will ultimately propel the boat.
• For a 16 oz bottle, about 14 g NaHCO₃ and approximately 190 mL of 5% vinegar solution should propel the boat down the track adequately if capped and designed with a small gas outlet. (See the Calculations worksheet answer key for sample calculations.)
  • Some students may strategize that if they use excess reactants, they will generate more gas and therefore more thrust. However, they will need to ensure it does not have too much thrust and fly off the track resulting in disqualification, which they may try to resolve by adding weights, such as modeling clay, small rocks, etc.
• There are various ways you could determine the “winners” of the race – you could set up two tracks and race two teams at a time with the winners of round 1 racing each other in round 2, and so on, in tournament-style brackets until you get one final winner. Alternatively, if you only want to set up one track to cut down on materials and prep time, you could do time trials for each boat one at a time, possibly using photogate timers if you have them, and the boat that goes the full length of the gutter in the fastest time wins.
• Ensure all groups get copies of the student activity sheet and the Calculations worksheet to keep track of their designs as they evolve. They will need these to write their final report.
• Students will submit a report (see student activity sheet for detailed requirements) that includes an introduction, their activity log describing what they did each day of the project, safety precautions, materials used, design schematics, calculations, trial data, and what they might change if they were to do it again. This should help them understand how scientists and engineers keep track of information related to their experiments and projects.
  • Alternatively, if you had time, you could have students give presentations to the class, rather than a written report, which would provide public speaking practice.
• Since students are working in teams, you may wish to have them evaluate their teammates throughout the process so that you can intervene if some students seem to be doing all the work or not allowing others on their team to participate fully.