Presentation on theme: "Reaction Chemistry: Theoretical Predictions Step 1: Find how much pressure is needed to go 25 feet – Experiment with several amounts of baking soda in."— Presentation transcript:
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 NaHCO 3 will generate a pressure of about 4.5 atms – 4.5 atms*.07 L/(.08205 atm-L/mol-K *293 K)= 0.131 mol CO 2 = 0.131 mol NaHCO3 or about 12.5 g NaHCO 3 Step 3: Find an amount of HCl that will react with more than 12.5 g of NaHCO 3 using the reaction: HCl (aq) + NaHCO 3(s) NaCl (aq) + H 2 O + CO 2 – Using an excess of HCl limits spew and makes the reaction go more completely –.018L HCl * 12.1 mol HCl/L * 1 mol NaHCO 3 / 1 mol HCl=.218 mol NaHCO 3 or 18.29g Therefore, 18 mL HCl and 12.5 grams of NaHCO 3 will create the neccessary pressure, 4.5 atms, while maintaining a mangable reaction rate, generating a decent yield and limiting or eliminating spew.
Data Amount of Baking Soda VinegarHClResults (observations) 9 g25 mL0Car went 5 feet 9 g25 mL0Car went 20 feet 9 g25 mL0Car went 23 feet 9 g050 mLCar traveled 3 feet, yellow spew 9 g050 mLCar didn’t travel at all 9 g050 mLCar didn’t travel at all (chem wipe was stuck) 15 g010 mLCar traveled 3 feet 15 g015 mLCar traveled 5 feet 15 g015 mLCar didn’t travel, releasing wrong 14 g025 mLCar traveled 30+ feet, really fast 14 g025 mLCar traveled 30+ feet, really fast 13 g022 mLCar traveled 30 feet 13 g022 mLCar traveled 32 feet 12.5 g020 mLCar traveled 28 feet 12.5 g018 mLCar traveled 28 feet 12.5 g018 mLCar 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.