By: Bob Becker, Kirkwood High School, Kirkwood, MO
The Audio Conductivity Tester Electrochemistry Demonstration Kit includes a conductivity tester that uses a piezoelectric buzzer and emits a sound when a circuit is complete. Students learn about electrolytes, nonelectrolytes, and ions.
Students reading a “Caution: Keep away from water!” notice on an electrical appliance may assume all water conducts electricity. Clear up their misconception with this easy-to-assemble conductivity tester that uses a piezoelectric buzzer and emits an audible sound when a circuit is complete. Use the first demonstration to engage students in a lively discussion about why three colorless liquids produce varying sounds—or no sound at all! In the second demonstration, students see and hear the effect concentration has on the conductivity of an electrolyte. The buzzer is sensitive enough to track the diffusion of ions as a few crystals dissolve in solution and form a complete circuit. The conductivity of acids and bases is explored in the third demonstration. Listen to the surprising results when an acid and base are combined! Enough chemicals are provided to perform each demonstration seven times with one reusable conductivity tester.
Concepts: Electrical conductivity, electrolytes vs. nonelectrolytes, ions.
Time Required: 20 minutes
Materials Provided: Ammonia, copper wire, copper(II) sulfate, sodium chloride, vinegar, battery clip with wire leads, Fahnestock clips, Petri dishes, piezo buzzer.
Note: A 9-V battery is required and available separately.
Correlation to Next Generation Science Standards (NGSS)
Science & Engineering Practices
Analyzing and interpreting data
Disciplinary Core Ideas
MS-PS1.A: Structure and Properties of Matter HS-PS1.A: Structure and Properties of Matter HS-PS2.B: Types of Interactions
Crosscutting Concepts
Structure and function Patterns Stability and change
Performance Expectations
HS-PS2-6. Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials.