With the Writing with Electricity Oxidation-Reduction Chemical Demonstration Kit, illustrate electrochemistry by using a copper “pen” to follow electrons in an electrolysis process. Students observe secret messages appear on filter paper.
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Get a charge out of writing with electricity! Demonstrate the key concepts of electrochemistry, including anodic and cathodic reactions, by using a copper “pen” to follow the flow of electrons in the electrolysis of aqueous potassium iodide. Students will observe secret messages that appear in filter paper containing starch and phenolphthalein indicators. The blue-black starch iodine complex is visible when the copper pen is negative, and the red color of phenolphthalein in base appears when the pen is positive. Identify the reactions responsible for each color change—and watch the electrons and concepts flow!Enough materials are included to perform the demonstration seven times.
Concepts: Electrochemistry, acid–base indicators.
Time Required: 15 minutes
Materials Provided: Potassium iodide, starch, phenolphthalein indicator solution, aluminum pan, filter paper, 9-V battery, battery clips, copper wire, and disposable pipets.
Correlation to Next Generation Science Standards (NGSS)
Science & Engineering Practices
Constructing explanations and designing solutions
Disciplinary Core Ideas
MS-PS1.B: Chemical Reactions
HS-PS1.B: Chemical Reactions
HS-PS1.A: Structure and Properties of Matter
HS-PS3.A: Definitions of Energy
Energy and matter
Stability and change
HS-PS1-2. Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.