Reaction Powered Car

By Josh Breen, Andrew Jeske, and Margaret Schneider

CBE 101 Dec. 7, 2009

The Team

From Left to Right: Andrew, Josh, and Margaret

The Reaction• Our Initial attempt for propelling our car was to use Alka-Seltzer and water:

C6H8O7(aq) + 3NaHCO3(aq) → 3H2O(l) + 3CO2(g) + Na3C6H5O7(aq)

This reaction was not able to create enough pressure to propel the car with a reasonable amount of materials.

• Next, we tried with baking soda and vinegar:NaHCO3(s) + CH3COOH(aq) → NaCH3COO (aq) + H2O(l) + CO2(g)

However, the amount required to make our car move caused our car to spewFinally, we tried using HCl and baking soda: NaHCO3(s) + HCl(aq) → NaCl (aq) + H2O(l) + CO2(g)

This propelled our car without any spewing.

CalculationsA sample calculation using 12 M HCl and excess baking soda:

12 mL HCl (1 L/1000 mL)(12 moles/1 L)( 1 mole CO2/ 1 mole HCl)= 0.144 moles CO2

Now we calculate the pressure in the 0.7 liter bottle:P=(nRT/V)=(0.144 moles CO2*0.08205 (L*atm/K*mol)*293 K/0.7 L)= 4.95 atm

Since the 0.7 liter propel hold 5 atm, we chose to use 12 mL of HCl and excess baking soda as the amounts to initially test our car with.

The Design

Bottle tilted at 6 degree

angle for minimal

spewage!

X cross beams in

base plates for extra support!

2 adjustable bars on top for minimum

wiggle!

Rotating front axle!

Stationary rear axle!

Spacers around wheel for minimal

frictionSchool spirit for awesomeness!

Trial 1 Trial 2 Trial 3 Trial 4 Trial 50

2

4

6

8

10

12

14

Distance (ft.)

The ResultsTrial # HCl (mL) Baking

SodaH2O (mL) Distance

(ft.)Spew

1 12 excess 10 12 yes

2 12 excess 0 5 no

3 15 excess 0 7 no

4 15 excess 0 5 no

5 15 excess 0 5 no

ConclusionOur car managed to move off the starting line without spewing, but it

did not get very close to the target range of 25 feet. Our best non-spew distance was 7 feet. We made it closer while spewing, and we could have gotten much farther while spewing, but we settled for a shorter, non-spewing distance.

If we were to try this experiment again, we could do much better even with a non-spewing car if a few modifications were made to our present car. We could lower the bottle angle so that our car would get more distance out of the same amount of reaction. The rear axle could be made to rotate to decrease friction. The whole car could be lowered down and made to have less air resistance. We could add an attachment to the nozzle so that there would be a smaller cross sectional area. Then we could add some sort of quick release valve so pressure wouldn’t be wasted while we spend time turning the nozzle on the propel bottle. There is also room for experimentation of different chemical reactions that may be more efficient.