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Product Highlights

• Observe how temperature, concentration, and the addition of a catalyst affect the rate at which a colorless solution changes to a deep blue color.
• High school teacher-led, student-engaged demonstration with enough materials for 5 performances.
• Carolina Kits 3D®—Labs that use phenomena to support NGSS and 3-dimensional instruction.

Students observe the phenomenon of chemical clock reactions. They then model these reactions on a particulate level and calculate reaction rates as the reciprocal of elapsed time for each trial. The effects of concentration, temperature, and catalysts on reaction rates are observed in separate demonstrations.

Time Requirement
Total, 45 minutes. Teacher prep, 15 minutes. Demonstration and discussion, 30 minutes.

Digital Resources
Includes 1-year access to digital resources that support 3-dimensional instruction for NGSS. Digital resources may include a teacher manual and student guide, pre-lab activities and setup videos, phenomenon videos, simulations, and post-lab analysis and assessments.

Performance Expectations
HS-PS1-4
HS-PS1-5

Crosscutting Concepts
Patterns
Energy and Matter

Disciplinary Core Ideas
PS1.B: Chemical Reactions

Science and Engineering Practices
Developing and Using Models
Constructing Explanations and Designing Solutions

Learning Objectives

• Develop and use a model to represent what happens in an iodine clock reaction.
• Use prior knowledge to predict the effect of altering variables in a clock reaction and calculate the rate of reaction.
• Illustrate and explain the iodine clock reaction on a molecular level.
• Explain how a catalyst affects reaction rates.

Prerequisite Knowledge and Skills
Students should be familiar with writing and interpreting energy level diagrams for a chemical reaction; chemical kinetics and how they are affected by concentration, temperature, and catalysts; writing chemical formulas; and writing and balancing chemical equations.