Primary Type: Lesson Plan
Status: Published
This is a resource from CPALMS (www.cpalms.org) where all educators go for bright ideas!
Resource ID#: 129120
Let's Get It Started: Chemical Reaction Rates
This one-day investigation begins with a teacher demonstration that introduces students to the nature of catalysts and how they influence chemical
reaction rates. Students then formulate hypotheses and collect data on the effects of temperature and concentration of a reactant on reaction
rates. Students will be able to graph their data (both individual and group) and compile/analyze class data using GeoGebra.
Subject(s): Science
Grade Level(s): 9, 10, 11
Intended Audience: Educators
Suggested Technology: Document Camera,
Computer for Presenter, Computers for Students,
Internet Connection, LCD Projector, GeoGebra Free
Software (Download the Free GeoGebra Software),
Smart Phone/Tablet
Instructional Time: 1 Hour(s) 30 Minute(s)
Keywords: Chemical reaction rates
Resource Collection: FCR-STEMLearn Physical Sciences
ATTACHMENTS
StudentDataSheetChemicalReactionRates.docx
LESSON CONTENT
Lesson Plan Template: General Lesson Plan
Learning Objectives: What should students know and be able to do as a result of this lesson?
The students will be able to:
1. Investigate the means in which the rate of chemical reactions can be changed.
2. Observe and describe the qualitative relationships between the rate of chemical reactions and the following factors:
Temperature
Concentration
Catalyst
3. Write a hypothesis, record observations, and gather data.
4. Graph temperature vs. rate and interpret the data.
5. Graph concentration vs. rate and interpret the data.
Prior Knowledge: What prior knowledge should students have for this lesson?
1. Students should be able to provide evidence that a chemical reaction has occurred.
2. Students should be able to identify and describe the types of chemical reactions.
3. If students have taken biology, they should have been introduced to catalysts (enzymes).
4. Students should be familiar with basic laboratory safety rules.
5. Students should be familiar with basic laboratory equipment.
6. Students should demonstrate basic measurement skills.
page 1 of 6 7. Students should demonstrate basic graphing skills.
Guiding Questions: What are the guiding questions for this lesson?
1. How can we influence the rate of chemical change?
2. How does a catalyst increase the rate of a chemical reaction?
3. How does concentration affect the rate of a chemical reaction?
4. How does temperature affect the rate of a chemical reaction?
Teaching Phase: How will the teacher present the concept or skill to students?
Starting the lesson (duration: 20 minutes)
Prior to the demonstration, the teacher should display on the board the chemical equation for the decomposition of hydrogen peroxide (2H2O2 → H2O + O2). The
teacher should ask the following questions:
1. Identify the type of chemical reaction.
2. How do you know?
3. What is the reactant of the equation?
4. Describe some properties (physical and chemical) of hydrogen peroxide.
It naturally decomposes and evolves oxygen gas. This solution is stored in opaque plastic bottles because ultraviolet light (which is a component of white/visible
light) also acts as a catalyst for this decomposition reaction.
5. What are the products?
6. Describe some properties (physical and chemical) of oxygen gas and water.
Teacher Demonstration
The teacher will demonstrate the catalytic decomposition of hydrogen peroxide. Safety goggles, gloves and a chemical splash tray should be used.
Materials:
Ring stand
Clamp
Test tube
2 - 25 mL graduated cylinders
2 - 150 mL beakers
30% hydrogen peroxide
Iron III chloride (0.1 Molar Solution)
Procedure:
1. Use a clamp to attach a test tube to a ring stand. Ensure that the test tube is in a vertical position.
2. Place the ring stand on the chemical splash tray, which is used to collect/contain any spills which result from the reaction.
3. Put on gloves and safety goggles.
4. Using the graduated cylinder, measure 20 mL of the hydrogen peroxide. Pour the solution into the test tube.
5. Ask students to make and write down their qualitative observations of the hydrogen peroxide. (Students are to remain seated in their desks and a safe distance
from the demonstration table.)
6. Using a clean graduated cylinder, measure 15 mL of the iron III chloride solution.
7. Pour the iron III chloride solution into a clean 150 mL beaker.
8. Ask students to make and write down their qualitative observations about the iron III chloride solution.
9. Prior to mixing the solutions, ask students to make predictions about what they think will occur when the solutions are mixed.
10. Ask students to share their observations and predictions with their elbow partner (person sitting next to them).
11. The teacher should ask two volunteers (limit responses for the sake of time) to share their predictions.
12. Pour the iron III chloride solution into the test which contains the hydrogen peroxide.
13. Students should write down their observations and compare what they observed with what they predicted.
14. Ask students to return to their elbow partner and share how their predictions compared with their observations of what actually occurred.
15. The teacher should now ask for new volunteers to compare their predictions with what they actually observed during the reaction. This discussion should be a
whole class discussion.
16. Students should observe that some of the yellow iron III solution remained in the test tube. Ask them what would happen if more iron III chloride solution was
added to the test tube?
17. Using the graduated cylinder that was previously used to measure the hydrogen peroxide, measure 15 mL of the solution and pour it into the test tube. Students
should once again observe how the iron III chloride solution catalyzes the decomposition of the hydrogen peroxide.
18. Explanation: The teacher should now add iron III chloride to the chemical equation which represents the catalytic decomposition of hydrogen peroxide. The teacher
should explain that the catalyst is written above the yield sign because it is neither a reactant nor a product.
19. Characteristics of catalysts should be addressed. Catalysts lower the energy required for the reaction to occur (lowers the activation energy), and therefore speeds
up the reaction. They are not consumed by the reaction and can be used over and over again.
20. Have students to reflect upon their initial predictions. Ask them to now write an explanation for the catalyzed decomposition of hydrogen peroxide using evidence
from the demonstration.
21. Teachers could perform "Genie in a Bottle" or "Elephant Toothpaste" as alternate demonstrations for catalysis of hydrogen peroxide.
22. Teachers can also place a burning splint inside the test tube during the chemical reaction to provide empirical evidence of the production of oxygen gas (burning
splint will ignite in the presence of oxygen gas).
Guided Practice: What activities or exercises will the students complete with teacher guidance?
Prior to students conducting the scientific investigations, the teacher will describe the proper equipment setup and procedures for each station. A copy of the
instructions should be printed out and posted at each lab station. Each student should have a copy of the instructions/procedures. Students should be reminded of lab
safety rules and proper measurement techniques. Students should also be told about appropriate procedures for cleaning up after the investigation.
Explain to students that they we will be exploring the effects of concentration and temperature on the rate of a chemical reaction. While in their lab groups, ask
page 2 of 6 students to share their thoughts about the influence of temperature and concentration on the rate. Have students to reflect upon kinetic molecular theory during this
phase of conversation. Discuss with the class possible answers. Allow a brief period for class discussion without revealing answers.
Instruct students to form two separate hypotheses regarding the effect of concentration on reaction rate and the effect of temperature on reaction rate. Explain that
the purpose of this scientific investigation is to provide evidence to answer/support their hypothesis.
The teacher should now model the correct procedure for Station 1 of the investigation:
1. Measure 10-mL of Solution A (IO3– ion) with a clean and dry graduated cylinder. Label this graduated cylinder with an A and use it to only measure Solution A. Pour
the solution into a clean 100 mL beaker.
2. Measure 10 mL of Solution B (HSO3– and soluble starch) with a second clean and dry graduated cylinder. Label this graduated cylinder with a B and use it to only
measure Solution B. Pour the solution into a clean 100 mL beaker.
3. Explain that the timekeeper should be ready to time the reaction and should begin timing as soon as the solutions are mixed.
4. Pour Solution A into Solution B. This will be the job of the principal investigator.
5. To ensure that they are well mixed, the solutions should be poured back and forth several times from one beaker to the other. (Students with physical disabilities
may need to use a stirring rod instead of pouring the solutions back and forth.)
6. Let the mixture stand.
Students should observe that a color change occurs. Ask, "What does this color change represent?" Answer: It indicates that the chemical reaction has occurred.
Students should be directed to their "Let's Get it Started: Chemical Reaction Rates" Lab Sheets. The teacher should explain that the Data Collection Sections should be
completed during the investigation. The Graphical Representations and Data Analysis and Conclusion sections should then be completed. These sections will be used to
determine the level of student understanding of the lesson objectives.
The teacher should have a sample set up of Station 2 prepared for students to reference. Explain how to make an ice bath and review basic procedures for measuring
temperature and for mixing the solutions.
Assigning students to cooperative groups based upon pre-assessment data is recommended. Each student should be assigned a specific role of responsibility. These
roles could include: principal investigator, materials manager, time keeper, and data collector.
Independent Practice: What activities or exercises will students complete to reinforce the concepts and skills developed in the
lesson?
Students will rotate through two lab stations as they investigate how concentration and temperature affect the rate of chemical reactions. In this investigation,
students will mix two solutions. One solution contains the hydrogen sulfite ion (HSO3–) and soluble starch. The other solution contains the iodate ion (IO3–). Iodine (I2)
produces a blue color in the presence of starch. This color change will mark the end of the reaction. The rate of the reaction can be found by measuring the time that
passes between the mixing of the two solutions and the initial observation of the color change. (A blue color will be observed).
1. Station 1: Investigate the effect of concentration on reaction rate.
2. Station 2: Investigate the effect of temperature on reaction rate.
Procedures for Reaction Rate Investigation Station 1:
Students should be in groups of 3 or 4. Students will now repeat the procedures modeled by the teacher for this station. The teacher should walk around and monitor
student progress and clarify procedures as needed:
1. Measure 10 mL of Solution A with a clean and dry graduated cylinder. Label this graduated cylinder with an A and use it to only measure Solution A. Pour the
solution into a clean 100 mL beaker.
2. Measure 10 mL of Solution B with a second clean and dry graduated cylinder. Label this graduated cylinder with a B and use it to only measure Solution B. Pour the
solution into a clean 100 mL beaker.
3. The timekeeper should be ready to time the reaction and should begin timing as soon as the solutions are mixed.
4. Principal investigator should pour Solution A into Solution B.
5. To ensure that they are well mixed, the solutions should be poured back and forth several times from one beaker to the other. (Students with physical disabilities
may need to use a stirring rod.)
6. Let the mixture stand.
7. The time keeper should stop timing at the precise moment that the color change is observed.
8. The data collector should record the data for the group and ensure that each group member has recorded the correct elapsed time.
9. The materials manager should rinse and dry the beakers.
10. Using graduated cylinder B, measure 10 mL of Solution B and pour it into one of the beakers.
11. Using graduated cylinder A, measure 9 mL of Solution A and pour it into the other beaker.
12. In order to dilute the solution, use a clean graduated cylinder, measure and add 1 mL of distilled water to Solution A.
13. Repeat the procedures in Step 3 (mixing and timing).
14. The data collector should record the data for the group and ensure that each group member has recorded the correct elapsed time.
15. The materials manager should rinse and dry the beakers.
16. Repeat step 4 for the four remaining dilutions of Solution A. Refer to the data table for the ratios of Solution A to distilled water. The data collector should record
the data for the group and ensure that each group member has recorded the correct elapsed time. The materials manager should rinse and dry the beakers after
each reaction.
Procedures for Reaction Rate Investigation Station 2:
1. Measure 10 mL of Solution A and pour it into a clean test tube.
2. Measure 10 mL of Solution B and pour it into a second clean test tube.
3. Make an ice water bath in a 250 mL beaker. (Fill the beaker half way with cool tap water and add ice cubes.) Place a thermometer in the beaker. Stir the water
(adding more ice if necessary) until the temperature of the ice water bath is approximately 5°C.
4. Put the two test tubes into the ice water bath. Allow the solutions to sit in the ice bath until they are the same temperature as the ice water. (If using only one
thermometer, be sure to rinse and wipe it off when moving it from one test to the other test tube).
5. The time keeper should prepare to begin timing the reaction when the solutions are mixed.
page 3 of 6 6. When the solutions reach the desired temperature (the same temperature as the ice bath) students should carefully mix the solutions by quickly pouring the
solutions back and forth between the two test tubes.
7. Return the test tube to the ice bath.
8. When the color change is observed, immediately stop timing and measure the exact temperature of the mixture. Record the temperature and elapsed time on data
table Part 2.
9. Repeat steps 1 and 2.
10. Now prepare a water bath with a temperature of approximately 15°C. Repeat steps 4 through 8 for this new temperature. Record the temperature and elapsed
time on data table Part 2.
11. Repeat these procedures using warm water baths. Warm tap water, a hot pot or a hot plate can be used to prepare the warm water at the following temperatures:
25°C, 35°C, 45°C.
12. The materials manager should rinse and dry the test tubes after each reaction.
Students should now complete the Graphical Representations and Data Analysis and Conclusion Sections of the student lab sheet. Their conclusion paragraph will
include an explanation of their results using evidence from the investigation as well analysis of the graphical representations.
Closure: How will the teacher assist students in organizing the knowledge gained in the lesson?
After groups have collected data for Stations 1 and 2, the data collector should bring their group's data to the teacher for input into GeoGebra for the whole class data
analysis. Class data should be projected on the board. The teacher should ask the following debrief questions:
Station 1:
1. Do you notice any patterns or trends regarding the effect of concentration on the reaction rate?
2. How does your group's data compare to the whole class data?
3. Describe the shape of the graph.
4. Were experimental procedures implemented consistently?
Station 2:
1. Do you notice any patterns or trends regarding the effect of temperature on the reaction rate?
2. How does your group's data compare to the whole class data?
3. Describe the shape of the graph.
4. Were experimental procedures implemented consistently?
Summative Assessment
Students will complete the "Let's Get it Started: Chemical Reaction Rates" Student Data Sheet, which includes hypotheses, observations, data collection, and
graphs.
The Data Analysis and Conclusion Sections of the student lab sheet will be completed by each student. Their conclusion paragraphs will include an explanation of
their results using evidence from the investigation as well analysis of the graphical representations. Possible sources of error which could impact validity of results
should also be addressed.
Class data could also be collected, graphed, and analyzed through GeoGebra software. The observations and data tables may be the same for the members of a lab
group but the hypotheses, graphs data analysis, and conclusion paragraphs should be their own work.
Formative Assessment
Formative assessment will occur throughout the lesson. Probing/clarifying questions and discussions will take place during the initial teacher demonstration and as
students collaborate in groups to conduct the scientific investigation. The teacher is constantly monitoring students' performance and understanding of the lesson
objectives.
During the investigation phase of the lesson, if the teacher notices students/groups with poor measurement technique, the following questions might be asked:
1. What is the correct method for reading the level of the liquid in a graduated cylinder?
Answer: The graduated cylinder should be placed on a flat level surface. The reading should be taken at eye level. Due to refraction of light, if the reading is taken
from above or below the meniscus of the liquid then the measurement may be inaccurate.
2. If you're holding the graduated cylinder during data collection, would the reading be accurate? Why or why not?
Answer: If I am holding the graduated cylinder in my hands, the equipment may be tilted either toward or tilted away from me. Because, the meniscus may
therefore appear to be either above or below the true level of the liquid, the reading would not be accurate.
3. If you use a different method each time you measure the volume of the mixture, does this affect the precision of your measurements? Why or why not?
Answer: I need to have clear controlled variables for my experiment. My methods for measurement should be consistent. If I use a different method for each trial, I
might have different values for each trial which would result in a lack of precision for my data.
4. How will data be collected?
Answer: I will use graduated cylinders to accurately measure the volume of the mixtures. A stopwatch will be used to measure the amount of time that it takes for
the reaction to occur. A thermometer will be used to measure temperature.
5. What units will be used?
Answer: Volume will be measured in milliliters (mL). Temperature will be measured in °C. Time will be measured in seconds (sec).
6. Does it make a difference if you are not consistent with the number of times you pour the liquid from one beaker/test tube to the other? Why or why not?
Answer: Yes, I need to have a consistent method for mixing solutions. I want to ensure that I am not affecting the rate of the reaction by increasing/changing how
well the solutions are mixed. I know that stirring/mixing can affect how one substance dissolves in another. I don’t know if mixing will affect the rate that a chemical
reaction occurs.
7. How will you ensure that the results of your experiment are valid?
page 4 of 6 Answer: In order to ensure that my results are valid, I need to set up a controlled experiment with controlled variables. If I only have one independent variable, the
data that I collect will accurately represent my dependent variable.
8. What did you observe when you used a greater concentration in your reaction? What was happening at the molecular level that could have given this result?
Answer: As the concentration of the reactants increased, the rate of the reaction increased. This was evident in the time measurement. As concentration increases,
there is an increase in the number of molecules available for collisions. This increase in collisions increases the reaction rate.
9. What did you observe when you performed the reaction at a greater temperature? What was happening at the molecular level that could have given this result?
Answer: As the temperature of the reactants increased, the rate of the reaction increased. As the kinetic energy of the molecules is increased, there is an increase
in both the number of collisions and the effectiveness of the collisions.
10. If the catalyst is not actually a part of the reaction, what is it doing to increase the rate of the reaction?
Answer: A catalyst lowers the amount of activation energy required to get the reaction started.
Feedback to Students
Immediate verbal feedback will be provided to students/groups during formative questions/discussions.
Written feedback to the lab report might include the following comments (see attached lab report):
Concentration
As the concentration of the solution is decreased (becomes more dilute from 10 mL to 5 mL), the recorded reaction time increased. The more dilute the solution,
the longer he reaction takes. The more concentrated the solution, the less time the reaction takes. Concentration of reactants affects the rate of reactions by
affecting the collisions of particles. As particles increase (increased concentration) the number of collisions between particles increases. This increase in particles
results in an increase in the rate of the reaction. The converse is also true. As the particles decrease (decreased concentration), the number of collisions between
particles decreases. This decrease in particles results in a decrease in the rate of the reaction.
Graphically, as the concentration (mL) of Solution A increased, the time decreased. This means that the increase in the concentration occurred at a faster rate.
Temperature
As the temperature increased from 5°C to 45°C, the recorded time for the reaction decreased. This decrease in time meant that the reaction occurred at a faster
rate as the temperature increased. This temperature increase causes the average kinetic energy of the particles to increase resulting in both an increase the
number of collisions between particles and more effective collisions between particles.
Catalysts
Catalysts remain unchanged during a chemical reaction. They influence reaction rate by lowering the activation energy of the reactants. The activation energy is the
amount of energy required to get the reaction started.
Conclusions
If students hypothesized that increases in both concentration and temperature would increase the rate of a chemical reaction, their conclusions would state that the
data supported their hypotheses (see above comments for concentration and temperature). Conversely, if students hypothesized that decreases in both
concentration and temperature would result in a decrease in the rates of the chemical reactions, their conclusions would state that the data supported their
hypotheses (see above comments for concentration and temperature).
If students erroneously hypothesized that increases in either concentration and/or temperature would result in decreased reaction rates, their conclusion would
state that the data did not support their hypotheses. The converse would also be true. (See comments above foe concentration and temperature.)
Collision Theory
Increasing the concentration of reactants increases the number of particles. As the number of particles increases, the number of collisions increases which results
in an increased reaction rate.
Increasing the temperature of the system causes the average kinetic energy of the particles to increase resulting in both an increase the number of collisions
between particles and more effective collisions between particles.
ACCOMMODATIONS & RECOMMENDATIONS
Accommodations:
Students will be given accommodations according to their Individualized Education Program (IEP). ELL students should be paired with a peer to facilitate
comprehension of directions, to aid in translation and to provide support with responses. Visual images of lab equipment and procedures can be provided to ensure
understanding of the activity. Sentence stems can be provided to support writing.
Struggling students might access the Understanding Chemistry: Rates of Reaction page from Chemguide for extra assistance.
Extensions:
Particle diagrams, energy diagrams and chemical equilibrium would be appropriate extensions for this lesson. Students could draw particle diagrams to illustrate
understanding of chemical concentration. The teacher could introduce the basic format of an energy diagram and ask students to research how a catalyst affects the
energy of a chemical reaction.
The simulation "Chemical Kinetics" from the Iowa State University Department of Chemistry could also be used as an extension.
Suggested Technology: Document Camera, Computer for Presenter, Computers for Students, Internet Connection, LCD Projector, GeoGebra Free Software, Smart
Phone/Tablet
page 5 of 6 Special Materials Needed:
Demonstration
Ring stand
Clamp
Test tube
2- 25 ml Graduated cylinders
2 - 150 ml beakers
30% hydrogen Peroxide
Iron III chloride (0.1 Molar Solution)
Student investigations (per lab group)
Safety goggles (per student)
Lab apron (per student)
250 mL beaker
2 – 100 mL beakers
2 – 10 mL graduated cylinders
2 – Test tubes (18 x 150 mm)
Thermometer
Timer (stopwatch, clock, cell phone)
15 mL Distilled water
Ice cubes
Hot plate
Solution A – 45 mL (In order to make one liter of this is a 0.02 M solution: dissolve 4.3 grams of potassium iodate (KIO3) in per liter of solution.)
Solution B – 60 mL (In order to make one liter of this solution: dissolve 4 grams soluble starch, 5 mL 1.0M H2SO4 and 2 grams sodium bisulfite (NaHSO3) per liter of
solution.)
Solutions should be prepared the day before the investigation.
Further Recommendations:
Teachers should reference Flinn Scientific, Inc. Safety Data Sheet (SDS) for safety guidelines and proper procedures for chemical disposal:
Potassium Iodate Solution
Sodium Bisulfite
Sulfuric Acid
Concentration will usually have the greatest effect on the rate of a chemical reaction. There are instances (zero order reactions) where the change in concentration
does not affect the rate of a chemical reaction. These reactions are beyond the scope of the complexity of this laboratory.
SOURCE AND ACCESS INFORMATION
Contributed by: Pia Carswell
Name of Author/Source: Pia Carswell
District/Organization of Contributor(s): Duval
Access Privileges: Public
License: CPALMS License - no distribution - non commercial
Related Standards
Name
Description
Explain how various factors, such as concentration, temperature, and presence of a catalyst affect the rate of a
chemical reaction.
Remarks/Examples:
SC.912.P.12.12:
Various factors could include: temperature, pressure, solvent and/or solute concentration, sterics, surface area,
and catalysts. The rate of reaction is determined by the activation energy, and the pathway of the reaction can
be shorter in the presence of enzymes or catalysts. Examples may include: decomposition of hydrogen peroxide
using manganese (IV) oxide nitration of benzene using concentrated sulfuric acid hydrogenation of a C=C double
bond using nickel.
page 6 of 6