Reaction-Powered Car Project

1. Reaction-Powered Car Project Group Members: Kelly Gutierrez, Nick Young, Travis Anderson & Alex Clemens

2. Reaction Chemistry (1/3) • Reaction 1: Baking Soda & Vinegar

3. Reaction Chemistry (2/3) • Reaction 2: Baking Soda & Hydrochloric Acid

4. Reaction Chemistry (3/3) • Reaction 3: Decomposition of Hydrogen Peroxide with Potassium Iodide as a Catalyst [used for competition] • After testing, we decided to reduce the amount of Hydrogen Peroxide used to 55 mL to 60 mL, instead of 76 mL, to reduce the amount of pressure contained in the bottle. • After using 20% Hydrogen Peroxide, we decided to mix the KI in some water because it reacted too fast. We later stuck with 10% Hydrogen Peroxide, still mixing the KI with water.

5. Car Design (1/2) • Design 1

6. Car Design (2/2) • Design 2 [used for competition]

7. Testing Results (1/2) For the first two reactions, we never recorded any valid results. We had many problems with holding the pressure in the bottle as we waited for the chemicals to react. Significant amount of pressure would always leak and our car never really moved. Since good bottles were limited, we decided to switch to a reaction where it reacted much quicker so we could open the nozzle before a significant amount of pressure was lost. That is why we decided to use the decomposition of hydrogen peroxide to produce oxygen gas with the use of potassium iodide as a catalyst. This reaction occurred very rapidly. 3% Hydrogen Peroxide used up a lot of solution. We needed one that was stronger like 20%, so we can use less. Using 20% Hydrogen Peroxide and Potassium Iodide reacted too fast, so we started mixing the KI in water beforehand and we stuck with 10% Hydrogen Peroxide.

8. Testing Results (2/2) The last 4 results were taken from the actual competition. Our car only went 10 ft, so we increased the amount of hydrogen peroxide by 10 mL. We lost a lot of pressure, so we tried it again. Our car went 50 feet, so we decided to cut it down to 40 mL and were careful with containing pressure. I made sure there was very limited pressure leak and our car went 22 feet. So the problem we’ve been having with consistency is due largely to the amount of pressure leaking from the bottle as we waited for the reaction to complete. We didn’t want to use 20% hydrogen peroxide, because we felt that a reaction that was too rapid was dangerous, because it exploded the first and only time we tried it.

9. Conclusions For our first car design, Dr. Skip said he noticed that our car didn’t run as smoothly as the other cars. We also had problems with keeping the bottle/vessel secure, because if it was loose, the car wouldn’t move as much as it’s suppose to. We completely redesigned our car and came up with a more compact design that was stronger and it ran much more smoothly. The bottle was also pretty well in tact and the car would have to be disassembled to take it out. After testing this new design, we added a couple pieces to make it a little bit stronger, because the bottle would slightly expand when the pressure was building up inside. For our car’s performance, we ran into the problem of pressure leaking. It was hard to completely solve this problem, because bottles were limited. We realized that the tape used to seal the bottle when we screw the lid back on only helped a little. Working with baking soda reactions took too long, whether we used hydrochloric acid or vinegar as the other reactant. As we waited for the chemicals to react, significant pressure should be lost. Therefore, we needed a reaction that would take occur much more rapidly. Our answer was the decomposition of hydrogen peroxide with potassium iodide as the catalyst. We first tried used 3% hydrogen peroxide. It was much more successful than our previous reactions. However, we used up a lot of solution each time since the solution was only 3% hydrogen peroxide. We tried out 20%, but the reaction took place as we were still pouring the KI in and it exploded. We then used 10% hydrogen peroxide and started mixing our KI in some water. Our inconsistency was due to the amount of pressure lost in that short amount of reaction time. If we were good at holding the pressure in, 4 atm of pressure was too much. So we reduced the pressure to about 3 atm. Again, it was hard to be consistent due to the pressure leak. On our last trial, we held the pressure in nicely and used only 40 mL of hydrogen peroxide to produce about 2 atm of pressure and our car went 22 feet, the closest to 25 feet its ever gotten.