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Research Experience for Teachers (2015-2016)

Electrochemistry

Travis Hartberger's Poster
Author: Travis Hartberger
Unit Title: Electrochemistry
Grade Level: 11 - 12
Subject: Advanced Placement Chemistry
Estimated Duration:
Unit Activities:

Pre/Post Test:

The Big Idea (including global relevance)

Changes in matter involve the rearrangement and/or reorganization of atoms and/or the transfer of electrons. In some particular cases, such as spontaneous redox reactions, or in a Galvanic Cell or battery, the transfer of electrons produces a current and potential to do work. The conditions of that reaction such as the species being oxidized or reduced, as well as the electrode type and surface area, and the electrolyte/salt bridge are factors that can enhance or reduce the current or voltage a battery provides.

Electrochemistry is increasingly important as we try to develop battery technology that is “green,” renewable, less toxic upon disposal, and, of course, effective at powering the device it’s designed to run. Statistics show that majority of students in grades 6-12 have a smart phone, which socioeconomically challenged households, can be the only source of internet; as a result, the concept of “battery life” is a very real connection to their lives.

Essential Questions

  • What kind(s) of reactions require/produce electricity, current, and voltage?
  • What chemical species are used in oxidation-reduction reactions?
  • How is a redox titration similar and/or different from an acid-base titration?
  • How is a redox titration similar and/or different form the operation of a Galvanic cell or battery?
  • Can the voltage of the chemical species be predicted?
  • What parts are needed for a Galvanic Cell or battery to operate?
  • How is a Galvanic cell or battery assembled?
  • What happens to batteries and their components when they die?
  • What factors contribute to the current or potential produced by a redox reaction?
  • Do those factors affect current or potential independently, or do they work cooperatively?

The Hook

  • Students will be provided with the materials to assemble a 3-part Galvanic Cell that will light an Red LED. Students will preview the functional components of a Galvanic cell (battery) using the “TED-Ed – How do batteries work? – Adam Jacobson.” Students will then assemble the 3-part Galvanic Cell, then, use it to sketch a model of a battery, annotating the functional components of the cell in their model. Students will then discuss the components of the cell, leading them to question, “what might happen if…?” a component is removed, altered in size, altered in placement, or a different color LED is used.
  • 3-part Galvanic Cell
    Students will make a simple galvanic cell that will light a light emitting diode (LED). This galvanic cell, which contains only three parts, can be assembled in a few minutes. Students will also be able to draw a cross-section of this cell in their interactive notebooks as a model for the components of a Galvanic cell/battery. Galvanic cells consist of three main parts: (1) the anode or negative electrode, (2) the cathode or positive electrode, and (3) the ionic conductor or the electrolyte that separates the electrodes. Despite its simplicity, students struggle to understand how such cells work. The three components of this cell are a piece of magnesium metal and two pieces of soaked filter paper, one containing copper ions and one containing an inert salt solution.
  • Adapted from: Eggen, P. and Skaugrud, B. (2015). “An Easy-To-Assemble Three-Part Galvanic Cell.” Journal of Chemical Education, Vol. 92, pp. 1053-1055.
  • How do batteries work – TED-Ed – Adam Jacobson


The Challenge

To build a high-performance battery using common household materials that should be able to power the motors of various toy cars.

Guiding Questions

  • What kind of battery(ies) is/are used to run small motors?
  • What are the components of a battery?
  • How is the assembly of a battery like that of a Galvanic cell?
  • What specific components are used to create the voltage or current that powers a toy car?
  • Where, in your home, can you find items to easily build your own battery?
  • What allows some batteries to run longer than others?
  • What allows some batteries to power larger devices than others?
  • What are some assembly problems that might result in a batter not operating or failing to power the car?


ACS (Real world applications; career connections; societal impact)

Students use batteries everyday, but rarely are asked consider what makes one battery greener or more effective than another. The frequency daily use of batteries in their lives makes this challenge hugely applicable to their world.

The production of batteries hasn’t always been environmentally friendly. Not only will students develop batteries to operate a toy car, they will consider how “green” the process by the amount of waste material it produces.

Chemical/Environmental engineering: the battery is blend of chemistry and environmental impact. TED Talks: the presentation puts students in the shoes of a producer and presenter.

Misconceptions

  • The ease of learning this content through acronyms (LEOGER, OILRIG, etc.) often lends itself toward memorization and recall, rather than application and critical thinking. Students are often successful writing half-cell reactions as well as labeling components of Galvanic cells; however, they often struggled and/or skip questions that require them to evaluate the impact of a change on the cell or the cell’s performance.

Unit Lessons and Activities

  • Lesson 1: During lesson one students will learn about electricity, basic circuitry, and the basics of electrochemistry (from identifying oxidation and reduction to designing/modifying electrochemical cells based on data, i.e. voltage, electrode mass change, etc.).
    • Activity 1: The Hook
    • Activity 2: Traditional Electrochemistry Content
  • Lesson 2: During lesson two students will learn how manipulating components of batteries/electrochemical cells changes their output (current, power, etc.), the disposal/recycling of batteries, and design their own battery to power a toy a car.
    • Activity 3: Variable Testing - Manipulating Components of Batteries
    • Activity 4: The Challenge
  • Evidence of CBL: L1A1 and L2A4
  • Evidence of EDP: L1A1, L1A2, L2A3, and L2A4


Additional Resources