Rainbow pH Demonstration (Kathryn Smith)
Author
Kathryn M. Smith, William S. Hart High School
Principles
Density
Acid-Base Indicators
Acid-Base Reactions
The pH Scale
Standards
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.
PS1-B Chemical Reactions:
The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.
Materials needed
A large graduated cylinder (250 mL to 500 mL)
Sodium Carbonate (Na2CO3)
1.0 M Hydrochloric Acid (HCl)
~5 mL of Universal Indicator (Can order from Flinn ~$25 for 1000 mL)
Procedure
Provide a step by step procedure that explains how the demonstration equipment should be used.
Explanation
Provide a solid scientific explanation for the principles illustrated by the demonstration equipment.
Questions
It's very possible that after seeing the rainbow in the graduated cylinder, that students would be naturally curious about the following things. See if they can generate the questions before you ask them.
Why don't the layers mix?
What causes the colors?
What happens if you mix all the layers?
Everyday examples of the principles illustrated
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Photos
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Movies
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References
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