Location: Peru
Scientist: Adriana Garcia, Wastewater Management Chemist

Lesson Summary

Adriana Garcia teaches students about wastewater treatment. She explains that one of the challenges with cleaning water is removing particles that are so small they do not settle or get caught in the filters. The best way to solve this problem is to use a chemical reaction that forms a precipitate. Students combine two clear colorless solutions and get a white precipitate, which they filter.

Special Instructions: This lesson will take two class periods. You will begin with a demonstration, and then students will conduct a chemical reaction that forms a precipitate. The precipitate will need to filter slowly and then dry overnight. On the first day, while students wait for the products to dry, introduce the chemical equation for this reaction. On the second day, as their chemistry challenge, students compare the precipitate to the reactants to find out if it truly is a different substance with different properties.

Key Concepts

  • Formation of a precipitate is a clue that a chemical reaction may have occurred.
  • A precipitate is a solid that forms in the chemical reaction between liquids.
  • A precipitate does not dissolve in the resulting solution.
  • The products of a chemical reaction are different from the reactants, but are made of the same type and number of atoms.

Materials for Lesson 3

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