Description
Students observe the osmotic pressure phenomenon of colorful upward-growing metallic silicate precipitates. The osmotic pressure phenomenon is the clue to why the precipitates are upward growing rather than sinking. Students illustrate and model what happens at a particulate level and write balanced chemical equations for the 4 precipitation reactions in this demonstration. They then connect the osmotic pressure phenomenon to real-world applications.
Time Requirement
Total, 25 minutes. Teacher prep, 10 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.
Crosscutting Concepts
Patterns
Science and Engineering Practices
Developing and Using Models
Constructing Explanations and Designing Solutions
Learning Objectives
- Write balanced equations for the formation of metallic silicates.
- Understand how the osmotic pressure of water produces columns of metallic silicates.
- Illustrate and explain the silicate precipitation reactions on a molecular level.
Prerequisite Knowledge and Skills
Students should be familiar with osmosis and osmotic pressure; writing chemical formulas; writing and balancing chemical equations and labeling states of matter for each reactant and product; and predicting products for double-replacement reactions.