Factors Affecting Reaction Rates
Factors Affecting Reaction Rates
Purpose: To investigate the factors that can speed up or slow down chemical reactions: temperature, reactant concentration, particle size, catalysts, and surface area.
Procedure Part 1: Temperature
a. Obtain three clean test tubes. Using a small graduated cylinder, pour 5ml 6M HCl into each. Place one tube in an ice water bath, one in a hot water bath at 50˚C, and leave one in a test tube rack at room temperature. Allow the tubes to sit undisturbed for ten minutes.
b. Roll three pieces of 1.0cmx2.0cm aluminum foil into three separate loose balls.
c. Add one ball of the aluminum foil to the room temperature HCl. Time the duration of the chemical reaction. Test the identity of the gas produced by using a burning splint. Record all observations.
d. Repeat for the HCl in the ice water bath and then for the HCl in the hot water bath.
Procedure Part 2: Catalyst
a. Obtain seven clean test tubes. Rinse out the small graduated cylinder from part one. Using the clean graduated cylinder, pour 5ml 1.5% H2O2 into each of the five test tubes.
b. Add 15 drops of the following solutions to the separate test tubes of 1.5% H2O2: 0.1M KI, 0.1M FeCl3, 0.1M MnCl2, 0.1M Fe(NO3)3, and 0.1M KNO3. Flick each tube to mix its contents. Observe and record the rate of gas evolution from each reaction. Use the terms fast, slow, very slow, or none. Describe the catalytic activity as high, low, or none.
Procedure Part 3: Concentration
a. Pour 5ml of each of the following HCl solutions into separate clean test tubes: 1M, 2M, 3M, and 6M.
b. Roll four pieces of 1.0cmx2.0cm aluminum foil into four separate loose balls.
c. Add one ball of the aluminum foil to the 1M HCl. Time the duration of the chemical reaction. Record all observations.
d. Repeat for the 2M, 3M, and 6M HCl.
Procedure Part 4: Particle Size
a. Roll one piece of 1.0cmx2.0cm aluminum foil into a tight ball. Put in a clean dry test tube.
b. Tear another piece of 1.0cmx2.0cm aluminum foil into small pieces. Put in a different clean dry test tube.
c. Add 5ml of 3M HCl to each test tube. Observe and record the results.
Data Table 1: Effect of Temperature on Reaction Rate
Condition / Time Started / Time Ended / Duration / Burning SplintIce Water Bath
Room Temp.
Hot Water Bath
Data Table 2: Effect of a Catalyst on Reaction Rate
Test / 6MHCl / 0.1M
FeCl3 / 0.1M
NaCl / 0.1M
Fe(NO3)3 / 0.1M
CaCl2 / 0.1M
KNO3 / 0.1M
MnCl2
O2
Evolution
Catalytic Activity
Data Table 3: Effect of Concentration on Reaction Rate
Condition / Time Started / Time Ended / Duration / Observations1M HCl
2M HCl
3M HCl
6M HCl
Data Table 4: Effect of Particle Size (or Surface Area) on Reaction Rate
Tight Ball of Aluminum
Shredded Aluminum
Analysis:
1. Write a balance chemical equation for the reaction between HCl and aluminum metal.
2. Many reaction rates approximately double for every 10˚C increase in temperature. Are your results in Part 1 consistent with this general statement?
3. Write a balance chemical equation for the decomposition of H2O2.
4. Which ionic compounds were effective catalysts in the decomposition of H2O2.
5. Examine Data Table 2 and identify the ion responsible for the catalytic activity.
6. How does the surface area of a substance change as it is broken into smaller pieces?
Conclusion:
1. Describe in your own words the effect of temperature on the rate of a chemical reaction. Explain this effect in terms of the collision theory of reactions.
2. Describe in your own words the effect of a catalyst on the rate of a chemical reaction. Explain this effect in terms of the collision theory of reactions.
3. Describe in your own words the effect of concentration on the rate of a chemical reaction. Explain this effect in terms of the collision theory of reactions.
4. Describe in your own words the effect of particle size (or surface area) on the rate of a chemical reaction. Explain this effect in terms of the collision theory of reactions.