Name______Date______Block______
Army Raft Design Challenge
As you have researched, in WW2 the Army (what would become the Air Force) stored safety rafts in their planes in case of emergency landings in the oceans during war. In 1943, Louis Zamperini and his crew’s plane was attacked by Japanese fighter pilots. The plane went down in the middle of the Pacific Ocean with no land in site. Thankfully the men had a raft which was easily inflated by the creation of CO2 gas.
You are now given the task to recreate these Army rafts. The winner of this challenge will be the raft that holds the greatest mass without sinking.
Acetic Acid and Sodium Bicarbonate
The next step of this will be determining how acetic acid and sodium bicarbonate react with each other. You must determine the ideal amount of acetic acid to react with sodium bicarbonate and create a large enough amount of gas to cause the raft to inflate and keep as many army men on the raft without sinking. As with any problem, engineers will face numerous challenges throughout the design process.
Engineering Challenge #1:You will only be given 25 mL of acetic acid for the reaction to cause the air bag to deploy. But the sodium bicarbonate amount can be ANY amount, you have to determine which amount will cause the right amount of reaction to produce the perfect amount of gas to keep your army men afloat.
Engineering Challenge #2:Chemicals cost money. Sodium bicarbonate costs approximately 3¢ per gram. Determine an amount of sodium bicarbonate so that the chemicals for your mock air bag will be as cheap as possible.
Engineering Challenge #3:The zip-seal bag (your mock raft) must inflate, but not pop open.
Engineering Challenge #4:Your mock army raft must be inflated enough so that they float, but also don’t fall off.
Day 1: Raft Design and Construction and First Round of Data Collection and Redesign
Day 2: Second Round of Data Collection
Day 3: Reflection
Day 1: Raft Design and Construction
The basic design of this will be to use a plastic bag and just place the sodium bicarbonate and acetic acid within the bag. However…..we are engineers here and must expand upon our planning. Are you going to want a multiple bag raft? Yes, you can do this if you can design a way for the reaction to happen so it benefits the army man. Another engineering hurdle is cost. You will have a budget of $30.00 for the whole project including the redesign and all your chemical reaction tests.Side note: this is $30.00 fake money…not real. Each supply item will be given a price, this includes your chemicals of sodium bicarbonate and acetic acid. You can only use the supplies provided.
Materials Price ListPlastic Bags / $3
Straws / $2
Sodium Bicarbonate (Baking Soda) / $.30 per gram
Acetic Acid (Vinegar) / $.50 per 25 mL
Masking Tape / $.50 per inch
Initial Design
Budget…how much money do you have left?Item and Cost / $30.00
Using the table below test the amounts of sodium bicarbonate (in grams). THESE ARE FACTORED INTO YOUR BUDGET!!! You don’t get free stuff as an engineer.
Amount of sodium bicarbonate used (grams) / Description of test: How did you test it? Did you change anything from the previous test? / Did the acetic acid react for this test?(Yes or No) / Do I need to add more or less sodium bicarbonate? / How did the raft float?
Based on the data I have gathered, I can conclude that I should use ______grams of sodium bicarbonate per 25 mL of acetic acid.
Provide evidence to support your reasoning on why that amount of sodium bicarbonate is the best for raft inflation?
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Day 1: First Round of Data Collection
Now gather data on your raft support the mass of the army men. Start small and work your way up in mass. .
Mass of the Army Men / State of the RaftNow you have some qualitative data on the effectiveness of your raft. Revisit your original design. Do you need to change anything? Perhaps the chemical reaction didn’t produced enough energy to create enough gas to inflate properly….if so what should you change? Did you use more than one bag? Did those other bags fill properly? Think through this.
** Remember the $30.00 was for the whole project. You may have to reuse some items due to constraints.
RedesignDay 2: Second Round of Data Collection
It’s the final test. The plane has crashed and we must bring these men to safety!!! How many army men can your raft can hold.
Mass of the Army Men / State of the RaftWhat were some successful aspects of your fellow classmates’ air bags? (Engineers share what went well and what did not frequently with each other to compare findings and come up with better solutions together)
Pros/Cons of My Army Raft ( My Thoughts) / Pros/Cons of My Army Raft (Others Thoughts)Day 3: Reflection
Name______Date______Block_____
Assessment:
Construct an explanation of how your raft as either successful or unsuccessful using the points below. All points have to be addressed in the explanation but not in any particular order. You can even address them multiple times in different ways.
SEP: Design a Solution to a Problem- Construct a design solution that uses an endothermic or exothermic reaction to solve a problem (raft)
DCI: Endothermic and Exothermic Reactions
- State the differences between endothermic and exothermic reactions
- Describe the flow of energy in endothermic and exothermic reactions
CCC: Energy
- Analyze the flow of energy and cycling of matter in a given system during an endothermic or exothermic reaction
- Describe using evidence the role of energy in endothermic and exothermic reactions and how it causes change to the surrounding area
Student Reflection/Self Score / Teacher Feedback/ Final Score
Name: ______Date: ______Block: ______
Army Raft Design Challenge
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