Goal: TLW be able to follow the scientific method in designing an experiment.
TLW be able to explain the laws of volume and pressure.
TLW be able to identify what a limiting reagent is and why it is important in a chemical reaction.
TLW be able to distinguish between fossil fuels and renewable energy sources.
This activity is used at the beginning of the year. The students are given a challenge to design a rocket that can launch itself and leave the surface of the Earth. The student that gets theirs the highest wins a King Size Snicker bar.
Problems students will have to solve:
What ingredients can be used - limit them to just a few (alka seltzer and water works much better then vinegar and baking soda).
Why do some canisters just pop while others go 20 feet in the air? (Fuji film canisters have an internal seal while Kodak ones seal at the edge. This makes the Fuji ones hold much more gas pressure.)
How do we determine the height.. (students must decide on a way to measure height.. Usually, they decide to set them off next to an exterior wall and count the bricks)
What is a fossil fuel and why is it important?
Introduction/review of the Scienctific method. Near the end of the period, while still reviewing, I take a Fuji film cannister and place a piece of Alka Seltzer (1/4 tablet works well) and about 5 ml of water in it. I cap it and place it cap-side down in a bucket on the floor. I set this away from the students, but where it can be seen. We continue talking until the canister explodes and hits the ceiling. The students are very interested in what I did. They are instructed that the following day they will receive more information on what happened.
Students are given a flyer instructing them that they are now part of a research team that must design a type of rocket to blast off but it cannot use any fossil fuels. I give them a list of materials on the handout which includes the above along with various other items like a 2 liter pop bottle, vinegar, baking soda, sugar, life savers, soda pop. They are given 15-20 minutes to draw and write out what they think will happen. The last 20 minutes of class are spent outside testing their rockets. Remember to have students wear eye protection.
Students are paired off today and given the chance to work in pairs now. Each pair must decide what they agree on and how to build their rocket. The pairs should each have a schematic of their rocket and a way to determine fuel efficiency. Most of the class is spent outside testing and re-testing their rockekts (they will need to decide how much of each chemical to use and have to give an exact amount in their lab report).
At the beginning of class, three students are selected to be the record keepers and brick counters. Students sign up to be in the order they want to compete. We move outside, students carry their materials (rockets) with them. We set them off. When things don't go as planned, the students are given a chance to correct any error and retry once. We return to the classroom where the lab report is begun.
We review the design of the winning rocket and decide why it worked the best. Students are exposed to air pressure and volume and the associated laws. The different combinations of reactants are discussed and we graph how much water gives the best height based on a given amount of alka seltzer. We also discuss why these rockets are not based on fossil fuel (they are running out and won't be around much longer )