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Product Highlights

• Predict what will happen when you combine and then shake a solution of dextrose, potassium hydroxide, and methylene blue.
• 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 that shaking a capped, half-filled bottle of a clear solution causes the solution to turn blue immediately. Upon standing, the blue color fades to colorless. The color can be regenerated numerous times by shaking the bottle and contents. Given that the bottle has dissolved solutes of glucose, potassium hydroxide, and a redox indicator (methylene blue), students apply their prior knowledge of chemical reactions to develop a model for what is happening at a molecular level. They use evidence to support the claim that oxygen in the air above the solution must be present to initiate the reaction. Shaking the bottle causes gaseous oxygen to dissolve in solution. Then, aqueous oxygen oxidizes colorless methylene blue to its blue oxidized state. Further evidence that oxygen is necessary is that after numerous cycles, it takes longer periods of shaking to turn the solution blue due to less oxygen being available in the air above the solution.

Time Requirement
Total, 20 minutes. Teacher prep, 5 minutes. Demonstration and discussion, 15 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-PS1-5

Crosscutting Concepts
Patterns

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 the blue bottle reaction.
• Write equations representing the 2 phases of the reaction.
• Illustrate and explain the reaction on a molecular level.

Prerequisite Knowledge and Skills
Students should be familiar with writing chemical formulas, balancing chemical equations, and interpreting redox reactions. They should also understand chemical kinetics and how concentration, temperature, and catalysts affect reaction rates.