2009 Chemical Reaction Car

1. Cameron Glasscock Evan Eichelberger Hannah Niestradt 2009 Chemical Reaction Car

2. Car Chemistry • The reaction we used was baking soda and hydrochloric acid. The chemical reaction that released carbon dioxide gas was calculated with this formula: • In order to figure out how much pressure we would be producing from the reaction we used the PV=nRT equation. R = 0.08205 atm*L/(mol*K) Volume bottle = 0.7 L HClMolarity = 12.1 mol/L • In all runs hydrochloric acid will be the limiting reactant. Through trials we were able to figure that we wanted about 5.5 atmospheres of pressure to move our car 25 feet. By plugging in 5.5 for the pressure we were able to solve for the moles of CO2 we wanted to produce, and because CO2 is a 1:1 ratio with HCl we would be able to calculate how much hydrochloric acid we needed, putting in excess baking soda for the reaction. 𝐻𝐶𝑙(𝑎𝑞)+𝑁𝑎𝐻𝐶𝑂3 (𝑠)→𝑁𝑎𝐶𝑙(𝑎𝑞)+𝐻2O(l)+C𝑂2(g)

3. Car Design The “Big Wheel”

4. Results Close, but not close enough...

5. Conclusions Our car ended up performing well, but the process was a frustrating one for our group. We started experimenting with baking soda and vinegar the first day and our car went a maximum of 5 feet (and most of the time it didn’t move at all). We then started using baking soda and hydrochloric acid, and we found that gave us better results. Now our car would go either not far enough or a lot further than was needed. So at this point, it was all about experimenting with different amounts of baking soda and hydrochloric acid. After many trials, we then thought of using water in addition to the original two reactants. The addition of water really made the difference in our car and finally we got our distance to around 24-26 feet. Then it came to the day of the competition and for some reason, our car would not perform. It either went way further than 25 feet or not far enough (our closest was about 3 feet). Our group concluded that the performance of the car was based on what we did at the starting line (how long we let the reaction go before we opened the cap). We came to this conclusion because we would put the same amount of baking soda, hydrochloric acid, and water each trial, but each trial we would get very different results. I think that if we were more consistent with what we did at the starting line, then our cars’ distance would have been more predictable. So, yes our car did perform (it moved forward in every trial and we were able to control the spew) but it could have been more consistent every run.

6. Redesign Ideas When we first built our car we built it so that the propel bottle was tilted up and this design proved to be unsuccessful; so we changed our design so that the bottle would lay flat. In our design, we had two small wheels in the back and one large wheel in the front. Something we could have changed would be we could have used 4 small wheels which would be less weight and less friction than the one large wheel. We wouldn’t change our reaction that we used because it made the car go and it produced little or no spew. But something that we could have improved upon is the amount of time we let the reaction build up in the bottle. It would be a matter of testing the car many times to get the timing just right, but I think this is definitely one of our errors that caused inconsistency with our cars’ distance. We probably should have timed the amount of time that we let the reaction build up and also we could have come up with a better method of putting the baking soda into the bottle.