Description
Demonstrate the phenomenon of hydrophilic polymers that can absorb several hundred times their own weight in water. For the first demo, students observe hydration of powdered sodium polyacrylate. In the second demo, students observe hydration of a type of sodium polyacrylate particle that has a great deal of molecular cross-linking. The third demo demonstrates how polyacrylamide crystals absorb water slowly and swell into transparent, irregular solids. Students demonstrate their learning by writing formulas and modeling how each polymer utilizes hydrogen bonding for water absorption.
Time Requirement
Total, 35 minutes. Teacher prep, 10 minutes. Hydration of sodium polyacrylate, 10 minutes. Hydration of sodium polyacrylate (snow polymer), 5 minutes. Hydration of polyacrylamide, 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.
Crosscutting Concepts
Structure and Function
Science and Engineering Practices
Developing and Using Models
Obtaining, Evaluating, and Communicating Information
Learning Objectives
- Draw structural formulas for monomers of sodium polyacrylate and polyacrylamide.
- Illustrate hydrogen bonding with water for each molecule.
- Brainstorm and record practical applications for these water-absorbent polymers.
Prerequisite Knowledge and Skills
Students should be familiar with ionic, covalent, and hydrogen bonding; and have an understanding of polar and nonpolar molecules and hydrophobic versus hydrophilic compounds.