Factors Affecting Rates of Reaction Part 1: Effect of Temperature on Alka-Seltzer: C6H8O7 + 3NaHCO3 → 3H2O + 3CO2 + Na3C6H5O7 ● Procedure: ○ Fill three cups about half-full with water. In one cup add several ice cubes. A second cup will contain water at room temperature. In the third cup add hot water (be careful, it's hot!) ○ Using your phone, record the time it takes for ½ of an Alka-Seltzer tablet to completely dissolve. ● Data: Complete the data table. Water Time to Completion Observations Cold Room temperature Hot ● Conclusion: ○ When temperature increased, the rate of the reaction: ________________. ○ Particle Diagram: Put on your “particle glasses” and take a look into each of your reactant containers. Add a caption to each diagram to explain what is happening to the particles involved that is causing the observed change in reaction rate. Low Temperature Particle Diagram High Temperature Particle Diagram Caption: Caption: ● Reasoning: (explain in the box how changing the temperature affected the rate using collision theory and the particle diagram) Part 2: Effect of Concentration: Magnesium ribbon in Vinegar: Mg + 2HC2H3O2 → Mg(C2H3O2)2 + H2 ● Procedure: ○ Obtain 2 – ~1 cm pieces of magnesium ribbon of approximately the same size and some vinegar. ○ Place one piece of Mg in two separate containers. ○ Pour enough vinegar (~10 mL) in one of the containers to cover the magnesium. ○ In the second container pour ~5 mL vinegar and ~5 mL water to cover the magnesium. ○ Let sit for 4 minutes and then record observations. ● Data: Complete the data table. Container ● Vinegar Concentration 1 All vinegar 2 ½ vinegar, ½ water (50% concentration) Observations Conclusion ○ When concentration of a reactant increased, the rate of the reaction _________________ ○ Particle Diagram: Put on your “particle glasses” and take a look into each of your reactant containers. Add a caption to the diagram to explain what is happening to the particles involved that is causing the observed change in reaction rate. Caption: ○ Reasoning: (explain how changing the concentration affected the rate using collision theory and the particle diagram) Part 3: Effect of Particle Size/Surface Area of TUMS: CaCO3 + 2HCl → CaCl2 + H2O + CO2 ● ● Procedure: ○ Obtain 2 TUMS tablets and two small containers. ○ Crush/break apart one of the TUMS tablets ○ Place the crushed/broken TUMS in a small container and pour ~20 mL 1 M HCl to cover the whole TUMS. Time how long it takes to react the TUMS. ○ Repeat the experiment with the whole TUMS tablet. Time how long it takes to react the TUMS. Data: Complete the data table. Substance Time to Completion Observations TUMS (solid) TUMS (crushed) ● Conclusion ○ When surface area of a reactant increased, the rate of the reaction _________________ ○ Particle Diagram: Put on your “particle glasses” and take a look into each of your reactant containers. Add a caption to the diagram to explain what is happening to the particles involved that is causing the observed change in reaction rate. Caption: ○ Reasoning: (explain how changing the surface area affected the rate using collision theory and the particle diagram) Part 4: Effect of a Catalyst: 2H2O2 → 2H2O + O2 ● Procedure: ○ Obtain hydrogen peroxide, 3 small scoops of potato, and salt. ○ Pour a small amount of hydrogen peroxide into two containers. ○ In one container, add 3 small scoops of potato. ○ In a second container add a small scoop of salt. ○ Record observations and the reaction rate as: no reaction, slow, medium, fast ● Data: Complete the table. Possible Catalyst NaCl Potato Observations Reaction Rate ● Which substances above are catalysts for the decomposition of hydrogen peroxide? Explain how you can tell.
