ACTIVITY in Electricity, Reduction, Redox Reaction, Galvanic Cells, Oxidation, Half Reactions, Cathode, Anode, Spontaneous Reactions , Electron Transfer, Electrons, Spontaneous vs. Non-spontaneous Reactions, Electrolytic Cells. Last updated January 26, 2022.
In this activity, students will use an animation to visualize 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).
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
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.
This activity supports students’ understanding of:
- Galvanic (voltaic) cells
- Redox reactions
- Half reactions
- Cathode and anode
Teacher Preparation: minimal
Lesson: 10-30 minutes
- Computer and projector with internet access
- Student handout
- No specific safety precautions need to be observed for this activity.
- 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.
- 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.
- 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).
- 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 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
For the Student
As you view the animation, answer the questions below.
- Which metal acts as the anode in this galvanic cell?
- Which metal acts as the cathode in this galvanic cell?
- At which electrode does reduction occur?
- At which electrode does oxidation occur?
- Which electrode loses electrons?
- Which electrode gains electrons?
- What causes the lightbulb to light up?
- What types of ions, positive or negative, flow from the salt bridge into the anode container? Why do you think this occurs?
- What types of ions, positive or negative, flow from the salt bridge into the cathode container? Why do you think this occurs?
- What happens to the size of the anode over time?
- What happens to the size of the cathode over time?
- Equations for galvanic cells (and other electrochemical cells and redox reactions) are often written in terms of their “half reactions,” the part of the reaction that happens at each electrode. These involve neutral electrode atoms, ions of the same element, and electrons as reactants and products. Based on what you saw in the animation, write the half reactions that occurred at the anode and the cathode.
- Electrochemical cells convert energy between chemical energy and electrical energy. Galvanic cells are the first type of electrochemical cell, and they utilize electrons flowing spontaneously in one direction to convert chemical energy into electrical energy, as you saw in this animation. Electrolytic cells are the second type, and they involve the reverse reaction of a galvanic cell – energy is added to the system to force the electrons to flow the other way in a non-spontaneous reaction, converting electrical energy into chemical energy. Research where you can find galvanic and electrolytic cells in use in your daily life. Include the resources you referenced.