Control the Reaction Rate of a Foaming Reaction

Overview

In this lesson, students will employ the enzymatic decomposition reaction of hydrogen peroxide to investigate how chemical reactions are affected by enzymes and different substrate concentrations. Students will be challenged to control the rate of the reaction by adjusting the amount of substrate and thus changing the catalase activity. Foam production, created by the enzymatic breakdown of hydrogen peroxide into water and oxygen, will function as a proxy for the reaction rate. Based on their results, students will then discuss chemical reaction rates based on the collision theory.

NGSS Alignment

This lesson helps students prepare for these Next Generation Science Standards Performance Expectations:

• HS-PS1-5. Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.

This lesson focuses on these aspects of NGSS Three Dimensional Learning:

Science & Engineering Practices	Disciplinary Core Ideas	Crosscutting Concepts
Planning and Carrying Out Investigations. Plan and conduct an investigation individually and collaboratively to produce data to serve as the basis for evidence, and in the design: decide on types, how much, and accuracy of data needed to produce reliable measurements and consider limitations on the precision of the data (e.g., number of trials, cost, risk, time), and refine the design accordingly. Constructing Explanations and Designing Solutions. Apply scientific principles and evidence to provide an explanation of phenomena and solve design problems, taking into account possible unanticipated effects.	PS1.B: Chemical Reactions. Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy.	Patterns. Different patterns may be observed at each of the scales at which a system is studied and can provide evidence for causality in explanations of phenomena.

Materials

For each student group:

• Test tubes, at least 1.5 cm ID and 10 cm long (6)
• Test tube rack, or modeling clay
• Graduated Pipettes, 3-mL (3)
• Tap water, room-temperature (1 cup)
• Access to sink
• Dishwashing liquid (detergent) (1/2 cup)
• 3% hydrogen peroxide (1 cup)
• Dried yeast, bread machine or rapid-rise (1 package or 7 g)
• Cups (5)
• Measuring spoons (teaspoon and tablespoon)
• Spoons or spatula for mixing
• Metric ruler
• Timer
• Calculator
• Graph paper or graphing software
• Paper
• Pen
• Paper towels

For teacher demonstration:

• Test tube, at least 1.5 cm ID and 10 cm long (6)
• 3% hydrogen peroxide solution
• Dried yeast, bread machine or rapid-rise (1 package, which is usually 7g)
• Tap water, room-temperature (about 1 cup)
• Cup
• Graduated pipettes, 3-mL