Summary

In this lesson students will be introduced to catalysts while expanding their knowledge of chemical reactions and stoichiometry. They will first learn about catalytic converters and then be challenged to create the best “catalytic converter” of hydrogen peroxide to oxygen gas in an inquiry-based activity.

Grade Level

High school

NGSS Alignment

This lesson will help prepare your students to meet the performance expectations in the following standards:

• HS-PS1-2: Construct and revise the explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.
• HS-ETS1-1: Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants.
• HS-ETS1-2: Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering.
• Scientific and Engineering Practices:
  • Analyzing and Interpreting Data
  • Planning and Carrying Out Investigations
  • Constructing Explanations and Designing Solutions

AP Chemistry Curriculum Framework

This lab supports the following units, topics and learning objectives:

• Unit 4: Chemical Reactions
  • Topic 4.7: Types of Chemical Reactions
    • TRA-2.A: Identify a reaction as acid-base, oxidation-reduction, or precipitation.
• Unit 5: Kinetics
  • Topic 5.1: Reaction Rates
    • TRA-3.A: Explain the relationship between the rate of a chemical reaction and experimental parameters.
  • Topic 5.11: Catalysis
    • ENE-1.A: Explain the relationship between the effect of a catalyst on a reaction and changes in the reaction mechanism.

Objectives

By the end of this lesson, students should be able to

• Plan and conduct an investigation.
• Describe the difference between a catalyst and reactant.
• Explain how a catalyst increases the rate of a reaction.
• Design an experiment to test what makes a good catalyst.
• Explain how a catalytic converter works.

Chemistry Topics

This lesson supports students’ understanding of

• Kinetics
• Chemical Reactions
• Catalysts
• Rate of Reaction
• Stoichiometry
• Catalytic Converters

Time

Teacher Preparation: 45-60 minutes

Lesson:

• Engage: 10 -20 minutes
• Explore: 40 minutes
• Explain: 10-20 minutes
• Elaborate: 35 minutes
• Evaluate: 80-90 minutes

Materials

Demonstration

• 40 mL of 30% Hydrogen Peroxide
• 5 mL of 2M KI or NaI
• 10 mL Dishwashing liquid
• 10 mL graduated cylinder (2)
• 100 mL graduated cylinder (2)
• Plastic tray, 2-3 inches deep
• Catalytic converter

Exploring Catalysts lab investigation (per group):

• 6 – 100mL beakers
• 60 mL of 3% Hydrogen Peroxide
• MnO₂ (~1 gram)
• NaCl (~ 1 gram)
• KI (~1 gram)
• Beef Liver (small piece)
• Potato (small cube)
• Scoopula
• Forceps

Designing a Catalytic Converter lab investigation (per group):

• ~50 mL of 3% Hydrogen Peroxide
• Scoopula
• Forceps
• Gas collection:
  • Graduated cylinder (100-250ml)
  • Erlenmeyer Flask (100-250ml)
  • Water Trough
  • Rubber stopper with hole
  • Tubing
• Other materials will vary by group

Safety

• Always wear safety goggles when handling chemicals in the lab.
• Students should wash their hands thoroughly before leaving the lab.
• When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.
• Students should wear proper safety gear during chemistry demonstrations. Safety goggles and lab apron are required.

Teacher Notes

• This resource could be used as a post-AP Chemistry exam activity.
• Engage: The teacher will demonstrate the decomposition reaction of H₂O₂ (Elephant Toothpaste). Before students come into the classroom prepare two different demonstration set-ups, one with and without catalyst (set-up and measure hydrogen peroxide in separate 100mL graduated cylinders). Use one 10mL graduated cylinder to contain the KI or NaI (aq) catalyst and dish soap while another has just water and dish soap. Have a catalytic converter (borrowed from auto shop) on display and two different smog pictures (options provided below) either printed for students to look at or projected. Ask students to determine how all of the materials are interconnected. Once they have had a couple of minutes, have students share ideas. Finally, perform elephant toothpaste demonstration teachers should practice this before demonstrating it in class). Students should complete the Demonstration Questions on the laboratory handout during this time.
  
  Suggested picture resources:
  • Side by Side Picture Smog Pictures of Beijing
    
  • Smog Calendar pictures of Beijing
    
• Explore: Students will move into the lab to “Explore Catalysts” by investigating the decomposition of hydrogen peroxide given four different catalysts and a non-catalyst to use along with a control sample. Each lab station will have access to 3% hydrogen peroxide, beakers, and five different substances. Students will set up a control sample of hydrogen peroxide, and will conduct 5 test reactions that combine a substance with a sample of hydrogen peroxide. It is important that students have a general understanding of chemical reactions, especially decomposition reactions prior to conducting this investigation. Students will make observations about how each reaction proceeds and compare it to the control sample and to the other reactions. Note that the teacher will need to cut the beef liver and potato into small pieces prior to the lab.

• Explain: Students will now collaborate in small groups and try to make connections between the demonstration, pictures, catalytic converter, and their observations from the inquiry activity. Students will be challenged to define the term catalyst, give examples of other catalysts that they may know, and describe other factors that may affect reaction rate. It might help to remind students of the expiration dates on the hydrogen peroxide bottles. Groups will then present their definitions and other thoughts to the whole class.
  
  
• Elaborate: Students will now be given time to explore multiple online sources (see below) to extend their knowledge of catalysts to a new situation, catalytic converters. Students will be able to connect the prior day’s learning to a discussion of how catalytic converters work and why they are important. After exploring the online sources, students will be given time to discuss in a small group setting and again present their findings to the whole class. The sources could be differentiated to groups based on ability level. Instead of each student reading the same sources, the teacher could assign different sources to each group and encourage the students to present their findings to educate the class. There is also an online quiz that could be used as a formative assessment. At the end of the activity, students should again be asked to connect all of the materials from the prior day’s demonstration and visuals.
  
  Suggested resources:
  
  Explore Curiosity
  How Stuff Works
  Explain that Stuff
  NOx and Acid Rain
  International Platinum Group Metals Association
  
  
• Evaluate: Students are now tasked with “Designing a Catalytic Converter” through a second lab based activity. They will create their own catalytic converter for an engine that operates on a new fictitious fuel and its only toxic byproduct is hydrogen peroxide. Students will design their own experiment to “neutralize” the toxic substance and create a safe product, oxygen gas. The students will base their success on the amount of oxygen gas produced. They are forced to use all of their prior knowledge gained from the previous activities. Students should create a plan should create a plan during the prior night’s homework. All procedures should be approved by the teacher before the students begin.
  
  
• Extension and Differentiation Ideas: The following could be used to change the rigor of the activities to fit the level of the students in the classroom.
  • Apply a price structure to materials and have a cost limit on the building of the catalyst
  • Students could alter other conditions that affect rate such as temperature and stirring
  • Limit the amount of time for the catalyst to operate
  • Limit the mass of catalyst able to be used
  • Students could design a system that works as the peroxide flows over a stationary catalyst.