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Indicator Sponge - A Discrepant Event
Chemical Demonstration Kit

Indicator Sponge - A Discrepant Event
Chemical Demonstration Kit, AP6160
Catalog Number
Indicator Sponge - A Discrepant Event
Chemical Demonstration Kit
Product Description

By: The Flinn Staff

Can Red + Red = Blue? Dip a red sponge into a red solution—watch it turn blue. Place the blue sponge into a blue solution—it turns back to red. How can that happen? Amaze your students as you introduce acid–base indicators with this “discrepant event” demonstration! Capture your students' attention and challenge their observation and prediction skills. Also makes a great safety demonstration—check to see who didn't clean up spilled acid by wiping the bench top with your magical “Indicator Sponge.” Teacher Demonstration Notes included. Enough materials are included to perform the demonstration seven times.
Concepts: Acid-base indicators.
Time Required: 15 minutes
Chemicals Provided: Hydrochloric acid solution, sodium hydroxide solution, red and blue food dye, and the indicator sponge.


  • Indicator Sponge Video
    Indicator Sponge Video
    Place a red sponge in a red solution and it comes out blue. So, naturally, the blue sponge turns red when you put it in a blue solution. Indicators!
Additional Resources
Flinn Catalog/Reference Manual Page 345
Flinn Middle School Catalog/Reference Manual Page 399
P.O. Box 219, Batavia, IL60510



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