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Product Highlights

• Observe a shift in the solubility of carbon dioxide in seltzer water as pressure is applied to the system.
• 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.

The color change phenomenon observed in this demonstration models Le Châtelier’s principle as it relates to pressure changes in gas reactions. Students observe an equilibrium shift for carbonated water from the product side to the reactant side, producing a new equilibrium with less acidity than the original solution. Evidence for this is shown by an acid indicator changing color and carbon dioxide gas bubbling out of the solution.

Time Requirement
Total, 20 minutes. Teacher prep, 10 minutes. Demonstration and discussion, 10 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-PS1-6

Crosscutting Concepts
Stability and Change

Disciplinary Core Ideas
PS1.B: Chemical Reactions

Science and Engineering Practices
Developing and Using Models

Learning Objectives

• Predict in which direction the equilibrium will shift in a system to which pressure is applied.
• Create and label a drawing that explains how the reaction occurs on a particulate level.
• Learn that reversible chemical reactions are dynamic processes dependent on ambient conditions.

Prerequisite Knowledge and Skills
Students should be familiar with reversible chemical reactions and have an understanding that all reversible reactions reach a state of dynamic equilibrium after a given time. Students should also understand that there is no overall net change in reactants or products since the forward and reverse reaction rates are constant.