Building a Better Battery (Kari, Paul, and Lourdes)

Author(s)

HS-ETS1-2. Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering.

Dimension 1: Scientific and Engineering Practices

• 1. Asking questions (for science) and defining problems (for engineering

  2. Developing and using models

  3. Planning and carrying out investigations

  4. Analyzing and interpreting data

  5. Constructing explanations (for science) and designing solutions (for engineering)

  6. Obtaining, evaluating, and communicating information

Dimension 2: Cross Cutting Concepts that have Common Applications Across Fields

1. Patterns

2. Cause and effect: mechanism and explanation

3. Scale, proportion, and quantity

5. Energy and matter: flows, cycles, and conservation

Purpose:

Salt bridges are a necessary component of a typical galvanic cell. This experiment allows for a creative exploration of the variety of designs that will function as salt bridges.

Materials needed

Procedure

1. Set up a galvanized cell using CuSO₄.5H₂0 solution & ZnSO₄ solution. See diagram above for reference.

2. Construct a salt bridge using any of the commercial products or any combination of two of them. Some examples may include, but are not limited to:

   • Obtain a 6-8 inch length of plastic tubing, two small bits of cotton to act as porous stoppers for the tubing.

   • Optionally, obtain a 6-8 inch length of string.

3. Optimize this basic battery design by changing one variable at a time in order to illuminate a light bulb. (HINTS: fuller cups, best salt bridge/concentration, parallel circuit)

4. Return to your prepared galvanic cell and apply the salt bridge to the cell.

   • What are the critical parts of a galvanic cell, in addition to the salt bridge?

   • Draw a diagram of a complete galvanic cell made with copper and zinc electrodes.

   • What is it that makes a salt bridge “good” or “not so good”?

   • What properties do your chosen materials have that make you think they will produce a good salt bridge?

WAIT! Do not write down an answer to the Final question until your Instructor tells you to.

• • Describe how your salt bridge performed.

  • Did you choose the best materials possible?

  • How did you optimize you battery? (Share with your peers).

  • If you weren't able to get illuminate an LED bulb, why do you think it did not work?

  • What would you do next time to create a better salt bridge?

Questions

• Describe REDOX. Which metal is undergoing oxidation? Reduction?

• What chemical function does a salt bridge serve in a galvanic cell?

• Which ions are migrating?

• In what direction are they moving? Why?

Photos

References

Website:

Voltaic Cell Tutorial:

Extension:

Human Salt Bridge!!!

Videos:

Video Quiz

Making a Salt Bridge Video

Hot Dog Clock Video