Summary

In this activity, students will view an animation that explores how a galvanic cell works on a particulate level. Copper and zinc are the chemicals depicted in the spontaneous reaction. The transfer of electrons and involvement of the salt bridge are highlighted, in addition to the half reactions that take place for Zn (Zn → Zn²⁺ + 2 e^-) and Cu (2 e^- + Cu²⁺ → Cu).

Grade Level

High School

NGSS Alignment

This activity will help prepare your students to meet the performance expectations in the following 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.
• Scientific and Engineering Practices:
  • Developing and Using Models

Objectives

By the end of this activity, students should be able to:

• Describe the parts of a galvanic cell, including the cathode, anode, and salt bridge.
• Identify where the reduction and oxidation half reactions occur in a galvanic cell.
• Describe the flow of electrons and salt bridge ions in a galvanic cell.

Chemistry Topics

This activity supports students’ understanding of:

• Galvanic (voltaic) cells
• Redox reactions
• Half reactions
• Cathode and anode

Time

Teacher Preparation: minimal
Lesson: 10-30 minutes

Materials

• Computer and projector with internet access
• https://teachchemistry.org/classroom-resources/galvanic-cell-animation
• Student handout

Safety

• No specific safety precautions need to be observed for this activity.

Teacher Notes

• All of the animations that make up the AACT Animation collection are designed for teachers to incorporate into their classroom lessons. Intentionally, these animations do not have any spoken explanations so that a teacher can speak while the animation is playing and stop the animation as needed to instruct.
• If you assign this to students outside of class time, you can create a Student Pass that will allow students to view the animation (or any other video or ChemMatters article on the AACT website).
• We suggest that teachers pause this animation at several points or watch it more than once to give students the opportunity to make notes, ask questions, and test their understanding of the concepts presented. The animation is only about 1 minute long and moves quickly, so students will likely require pausing or multiple viewings to successfully complete the student activity sheet if you choose to use it. Particularly, the full schematic diagram with all parts labeled is only on the screen for a few seconds initially (it is revisited throughout the animation), but students will need it to answer the first four questions, so you may want to pause it on that opening image and give them some time to process it.
  • As a more visual alternative to the first four questions in the student activity sheet, you could replace those questions with a screenshot of the galvanic cell setup at the start of the animation that has blank boxes over the labels, and have students fill them in.
• This animation provides a basic introduction to the various parts of a galvanic (voltaic) cell. In this animation, the zinc/zinc sulfate cell is the anode and the copper/copper(II) sulfate is the cathode. Students will see the zinc lose two electrons, which travel through the wire and light up the lightbulb before they reduce a copper(II) ion to a neutral copper atom. You may want to introduce students to some galvanic cell/redox reaction vocabulary ahead of time so they are at least familiar with the words before viewing, but you could also show the animation as an introduction and discuss what the terms mean in more detail after viewing.
• You may wish to draw students’ attention to the color change in the copper(II) sulfate solution in the last segment of the animation, which is a result of the decreasing concentration of copper(II) ions as they are reduced and deposited onto the copper electrode.
• The first extension question involves writing half reactions for each electrode. If you have already taught your students how to write half reactions, you can include this question with the rest of the questions, rather than as an extension.
• The second extension question introduces the concept of electrolytic cells as essentially the reverse of galvanic cells. While galvanic cells take advantage of a spontaneous reaction (no external energy required), electrolytic cells are non-spontaneous reactions and need an external energy source to force electrons to flow in a direction opposite their natural tendency. If you assign this question, students will likely provide rechargeable batteries as an example of both – galvanic cells when in use powering an electronic device, electrolytic cells when being charged.
• Related classroom resources from the AACT Library that may be used to further teach this topic:
  • Simulation: Galvanic/Voltaic Cells
  • Lesson Plan: Galvanic Cell Exploration
  • Lab: Four-Way Galvanic Cell
  • Lesson Plan: How Fuel Cells Work
  • Video: Hybrid and Electric Cars Video
  • Lesson Plan: Exploration of Electrolytic Cells
  • Lesson Plan: How Far Can We Go?
  • Lab: Reactivity & Electrochemistry
  • Lab: Electrolysis of Water