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Activity (Hands-On)Grades 7 - 8

Mines to Mobiles: Aqueous Solutions and Environmental Chemistry

A photo showing a group of students filtering their dissolved salt and sugar aqueous solution through a coffee filter. This demonstrates the “REE purification step” in mining.Students filter their solution

Students are challenged to efficiently extract a model rare earth element, terbium, which is essential for electronics but typically refined using harmful acid-washing methods. Students first learn about water and solution properties such as hydrophobic/hydrophilic interactions, solubility, and the effects of temperature and agitation. They then apply this knowledge to a simulated extraction challenge: separating black pepper (terbium) from a solution of water (acid), salt (calcium), and sugar (iron). Finally, competing student groups must determine the fastest, most cost-effective combination of variables (temperature, agitation, etc.) to dissolve the salt and sugar, leaving only the "purified" pepper, thereby modeling the innovative and fiscally responsible problem-solving used by environmental engineers to safely extract rare earth elements.

Environmental engineers are challenged to create eco-friendly and cost-effective solutions for metal ore mining and refining amid climate change. To tackle large-scale problems, engineers work on small-scale models in labs that can be scaled up for industry. They plan based on prior research, collect and analyze data through iterations, collaborate with others, and continuously test and improve solutions. Students will follow the same engineering process using affordable and safe alternatives to acid and metal ores on a small scale.

After this activity, students should be able to:

  • Describe aqueous solutions in terms of solute and solvent, and concentration.
  • Describe up to four ways to speed up the dissolution process of a solute into a solvent.
  • Investigate and model how the temperature of solvent, surface area of solute, and agitation of solution affect the rate of dissolution of solid solutes in aqueous solutions.
  • Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.

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