### Reaction Powered Car

Reaction Powered Car
Chelsey Chapman
Mallory Goff
Brian Livingston
Group Picture: Chelsey C, Mallory G, Brian L
Reaction Chemistry: Theoretical Predictions
• H3C6H5O7 (aq) + 3NaHCO3 → 3CO2 (g) + 3H2O (l) + NaC6H5O7 (aq)
• 1 Tablet of Alka-Seltzer contains 1 gram of citric acid and 1.916 grams of
sodium bicarbonate (baking soda)
• (1g citric acid)/(136 g/mol) = 0.00735 mol citric acid per tablet
• (1.916g baking soda)/(48g/mol) = 0.0400 mol baking soda per tablet
• Using 6 tablets:
– (6*0.00735 mol citric acid)/(3 mol CO2/1 mol citric acid) = 0.1323 mol CO2
– P=nRT/V P=(.1323 mol CO2)(.08205 L*atm/(mol*K))(273 K)/0.600 L = 4.94 atm
• Using 5.5 tablets, the pressure in the bottle is 4.53 atm
• Using 6.5 tablets, the pressure in the bottle is 5.35 atm
• Using 7 tablets, the pressure in the bottle is 5.76 atm
Car Design
Testing Results: Data + Plots
Distance Car Traveled (feet)
Practice Runs with 100 mL of Water
Practice Trials Data Table:
35
30
25
20
15
10
5
0
0
2
4
6
8
# of Alka-Seltzer
Tablets
amount of water used
(mL)
Distance
(ft)
8
8
7
6.5
6.5
6
100
100
100
100
100
100
30
4
28
18
22
15
10
# of Alka-Seltzer Tablets Used in Reaction
Testing Trials Data Table:
# of Alka-Seltzer Tablets amount of water used (mL)
Distance
6
100
180 in - out (9.8 ft)
6
100
out
6
100
out
Conclusion:
Performance and Re-Design Ideas
Performance:
In trial runs, our car perform fairly consistently with good results. On
the day of the finals, our car did not perform as it did previously. We
believe this is because the plastic had bent overnight beneath the
pressure of the water bottle and rubber bands. We re-designed it
towards the end of the finals but the new lightweight design could not
withstand the acceleration that our previous design could. Because we
were not able to practice consistently on this new design, it spun out of
control on all three runs during the competition.
Re-Design Ideas:
A lightweight design with the propel bottle positioned lower to the
ground. To compensate for the new design, less tablets and water
would need to be used. It would also be beneficial to make sure the
wheels could move freely and travel in a straight line by allowing them
more room to spin.