Reaction Powered Car

Ahmad, Sandy, Daniel

Reaction Chemistry: Theoretical Predictions

• Step 1: Find how much pressure is needed to go 25 feet– Experiment with several amounts of baking soda in an excess of vinager to find the

amount that will give you the right pressure– Found to be about 4.5 atms

• Step 2: Find how many moles of NaHCO3 will generate a pressure of about 4.5 atms– 4.5 atms*.07 L/(.08205 atm-L/mol-K *293 K)= 0.131 mol CO2 = 0.131 mol NaHCO3 or about

12.5 g NaHCO3

• Step 3: Find an amount of HCl that will react with more than 12.5 g of NaHCO3 using the reaction: HCl(aq) + NaHCO3(s) NaCl(aq) + H2O + CO2

– Using an excess of HCl limits spew and makes the reaction go more completely– .018L HCl * 12.1 mol HCl/L * 1 mol NaHCO3/ 1 mol HCl= .218 mol NaHCO3 or 18.29g

• Therefore, 18 mL HCl and 12.5 grams of NaHCO3 will create the neccessary pressure, 4.5 atms, while maintaining a mangable reaction rate, generating a decent yield and limiting or eliminating spew.

Reaction Car Design

DataAmount of Baking Soda

Vinegar HCl Results (observations)

9 g 25 mL 0 Car went 5 feet

9 g 25 mL 0 Car went 20 feet9 g 25 mL 0 Car went 23 feet

9 g 0 50 mL Car traveled 3 feet, yellow spew

9 g 0 50 mL Car didn’t travel at all9 g 0 50 mL Car didn’t travel at all (chem wipe was stuck)15 g 0 10 mL Car traveled 3 feet15 g 0 15 mL Car traveled 5 feet15 g 0 15 mL Car didn’t travel, releasing wrong14 g 0 25 mL Car traveled 30+ feet, really fast

14 g 0 25 mL Car traveled 30+ feet, really fast

13 g 0 22 mL Car traveled 30 feet

13 g 0 22 mL Car traveled 32 feet

12.5 g 0 20 mL Car traveled 28 feet12.5 g 0 18 mL Car traveled 28 feet12.5 g 0 18 mL Car traveled 25 feet

Conclusion• We started with vinegar and baking soda, and there was a lot of

spew. Then moved on to HCl and baking soda. We had problems with the chem wipe getting caught, so we constructed a funnel out of paper to pour the baking soda into the bottle. We did a lot of trials with the HCl and baking soda because the reaction was inconsistent. We ended up using 18mL of HCl and 12.5 g of baking soda.

• We redesigned our car because the wheels kept getting stuck because they were too close to the bottle and the car wouldn’t move. The car chassis also had a significant amount of body lean, which absorbed some of the car’s forward momentum. Our new design corrected for these flaws and proved to be much more reliable.