By: Mark Langella, Mahopac High School, Mahopac, NY
The Intermolecular Attractions Multi-Demonstration Kit for chemistry shows students what happens when molecules attract each other—or don’t. Students study hydrogen bonding, dipole–dipole attractions, cohesive and adhesive forces and more.
Molecules can’t be seen, but we can see the forces between molecules. Use this set of four demonstrations to show students what happens when molecules attract each other—or don’t! • Floating Oil Droplet—The difference in densities of water and ethyl alcohol causes an oil droplet to “float” in the middle of a beaker. • Bubble Shapes—Straws and twist ties are used to create beautiful geometric bubbles when dipped in a soap solution. • Capillary Action—Measure and compare the ability of water and ethyl alcohol to rise in a glass capillary tube. • Vanishing Volume—What happens to the 5 mL that was lost when 50 mL portions of water and ethyl alcohol are added together?
Use each demonstration separately to illustrate different types of intermolecular forces, or perform them all together for review or assessment.
Concepts: Surface tension, hydrogen bonding, dipole–dipole attractions, cohesive and adhesive forces, London dispersion forces. Time Required: 30 minutes
Correlation to Next Generation Science Standards (NGSS)
Science & Engineering Practices
Asking questions and defining problems Developing and using models
Disciplinary Core Ideas
MS-PS1.A: Structure and Properties of Matter HS-PS1.A: Structure and Properties of Matter
Crosscutting Concepts
Patterns Cause and effect Systems and system models Energy and matter Stability and change
Performance Expectations
MS-PS1-1. Develop models to describe the atomic composition of simple molecules and extended structures.
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