voltaic cell experiment materials

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Making and Testing a Simple Galvanic Cell.

Introduction: (initial observation).

Galvanic cell is a device in which chemical energy is converted to electrical energy. In a galvanic cell Oxidation-Reduction chemical reactions produce electricity that can be used to turn on a flashlight lamp. Most dry batteries are actually some kind of galvanic cell.

A simple electrochemical cell known as Daniell cell can be made from copper and zinc metals with solutions of their sulfates. English chemist John Frederick Daniell developed this voltaic cell in 1836.

In this project I will make a simple galvanic cell and use it to experiment and identify the conditions that affect the production of electricity in a voltaic cell such as Daniell cell.

This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “Ask Question” button on the top of this page to send me a message.

If you are new in doing science project, click on “How to Start” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.

Project advisor

Avoid contact with chemicals. Goggles must be worn throughout experiment.

Information Gathering:

Gather information about different galvanic cells or electrochemical reactions that produce electricity. Read books, magazines or ask professionals who might know in order to learn about the factors that affect the production of electricity in a galvanic cell. Keep track of where you got your information from.

Make yourself familiar with the terms anode , cathode , oxidizing agent, reducing agent, and electromotive series .

Following are samples of information that you may find.

A Galvanic cell is an electrochemical cell that uses a spontaneous chemical reaction to produce electrical energy. Also known as a voltaic cell.

A galvanic cell is usually made of an electrolyte and two electrodes made of two different metals (with two different reactivity rates).

The primary difference between metals is the ease with which they undergo chemical reactions. The elements toward the bottom left corner of the periodic table are the metals that are the most active in the sense of being the most reactive. Lithium, sodium, and potassium all react with water, for example. The rate of this reaction increases as we go down this column, however, because these elements become more active as they become more metallic.

Classifying Metals Based on Activity

The metals are often divided into four classes on the basis of their activity, as shown in the table below.

Common Metals Divided into Classes on the Basis of Their Activity

Class I Metals: The Active Metals Li, Na, K, Rb, Cs (Group IA) Ca, Sr, Ba (Group IIA) Class II Metals: The Less Active Metals Mg, Al, Zn, Mn Class III Metals: The Structural Metals Cr, Fe, Sn, Pb, Cu Class IV Metals: The Coinage Metals Ag, Au, Pt, Hg

The most active metals are so reactive that they readily combine with the O2 and H2O vapor in the atmosphere and are therefore stored under an inert liquid, such as mineral oil. These metals are found exclusively in Groups IA and IIA of the periodic table.

The most common voltaic cells are made of two electrodes, one from class II metals and the other from class III metals. Electrolyte is usually a salt solution of the class III metal. In this way the class III metal will be reduced to metal and the class II metal will be oxidized and become a salt and enter the electrolyte solution.

For example if you use magnesium from class II metals and copper from class III metals, the oxidation-reduction can be explained using the following formula.

If other metals are used, similar explanations can be used.

Mg(s) + Cu2+(aq) ==> Mg2+(aq) + Cu(s) + 1.5v

This reaction is an oxidation-reduction reaction in which the magnesium is oxidized to Mg2+ ions and Cu2+ is reduced to metallic copper. The result of this reaction is a transfer of electrons which provides the power required to light the flashlight lamp.

Common problems: (important)

The common problem in making a galvanic cell is that the reducing metal precipitates over the oxidizing metal and the current stops. For example when you use copper and zinc as electrodes and copper sulfate as an electrolyte, in a few seconds copper will precipitate over zinc, so the condition will change like both electrodes are copper. This condition stops the chemical reactions and production of electricity. The challenge is finding a method to prevent copper from precipitating over zinc.

One common method is using a two part container where these two parts are separated from each other using a porous material such as unglazed ceramic. ( See details here ) In this way one side of the container will have copper electrode and copper sulfate, and the other side will have zinc electrode and zinc sulfate.

The other method is using two separate containers and using a salt bridge to connect two containers to each other.

As shown in this picture, Fingers are used in place of a salt bridge in an electrochemical cell. The voltage produced is almost the same as the standard cell potential.

Salt Bridge is a U-shaped tube containing electrolyte, which connects two half-cells of a voltaic cell.

Salt bridge electrolyte is usually a gel containing a salt such as potassium nitrate.

To make a salt bridge, heat 150 mL of distilled water to boiling in a 400 mL beaker. Add 3 g of agar and stir the mixture as it boils until a uniform suspension forms. Remove the beaker from the heat and stir in 15 g of KNO3 until the salt dissolves. Pour the warm mixture into a U shape tube until it is completely filled. Keep it upright and let it set overnight. Once the agar is set, store the salt bridges in plastic bags to prevent drying out.

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.

The purpose of this experiment is to learn about electrochemistry and oxidation-reduction reactions through the construction and operation of a simple galvanic cell.

Find out what factors affect the voltage and the maximum electric current produced by a galvanic cell.

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

Independent variables are the types and sizes of electrodes.

Dependent variables are the voltage and the maximum electric current produced by the galvanic cell.

Controlled variables are temperature, electrolytes, and experiment procedures.

Hypothesis:

Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis. Following is a sample hypothesis:

Voltage between two electrodes is a function of the electrode metals and the electrolyte. If the difference between the reactivity of electrode metals is more, we expect a higher voltage.

The maximum electric current depends on the size of electrodes. As the surface of electrodes in contact with electrolyte increases, more chemical reaction will happen and as a result more electricity will be produced.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”

Introduction:

In this experiment an inexpensive cell is made from materials obtained locally. Test the cell by connecting it to a 1.5-volt flashlight lamp and observing whether or not the lamp will light. In addition, four or more of these cells can be connected in series to form a battery that can power a small radio or other device that operates on direct current.

See the list of material section before reading the procedure.

• Prepare a test lamp by soldering wire test leads to a 1.5-volt flashlight lamp. Attach alligator clips to the ends of the leads.
• Obtain strips of magnesium and copper, each strip should be 2.5 cm longer than the height of the beaker being used. Sand the strips until they are shiny.
• Tie a knot with string or use a non-reactive clamp in one end of dialysis tubing that has been soaked in distilled water. The length of tubing should be long enough so that it overlaps the edge of the beaker by 2.5 cm.
• Fill the dialysis tubing with the prepared copper(II) sulfate solution. Place the copper strip in this piece of dialysis tubing that is now filled with copper(II) sulfate solution and use string or a rubber band to secure the top of the dialysis tubing around the copper. Leave 2.5 cm of copper sticking out of the tubing.
• Fill the beaker with the prepared sodium sulfate solution, place both the dialysis tubing, containing the copper and copper(II) sulfate solution, and the magnesium strip in the beaker. Place the magnesium strip as far away as possible from the dialysis tubing. Secure both the magnesium strip and the copper strip in the dialysis tubing in the beaker by bending them over the edge of the beaker.
• Complete the circuit by attaching one alligator clip to the copper strip and the other to the magnesium strip.
• Observe and record any activity taking place at the metal strips, the solution (especially color changes), and the test lamp. Also measure and record the voltage between electrodes with and without the test lamp connected. Also measure the electric current without a test lamp in the circuit.
• Connect several cells in series and measure the voltage again.
• Try making cells with zinc or aluminum in place of the magnesium.
• Try making cells with larger or smaller electrodes
• All solutions may be flushed down the drain with water.

Dialysis tubing is a porous membrane that allows SO42- ions to pass, but blocks Zn2+ and Cu2+ ions. A cellophane tube and a ceramic tube will also work as well.

I think intestine casings (skin of sausage) may also work as a membrane, but I have not tried it. You can purchase these from your local meat market or butcher’s shop. If you try this, please let me know about the result. Send an email to [email protected].

The top of the membrane must not be air tight. Some hydrogen gas may form on the zinc electrode and needs to exit.

Inside the membrane sack, you can use zinc sulfate, Sodium sulfate, potassium sulfate or ammonium sulfate.

Substitute chemicals and electrodes:

As you see in the above diagram, you can substitute magnesium with zinc and sulfate salt with nitrate salt with similar results.

Avoid contact with solutions. Goggles must be worn throughout experiment.

Materials and Equipment:

250-mL beaker or a mug dialysis tubing hook-up wire or bell wire 1.5-volt flashlight lamp with less than 100 milliamp rating alligator clamps crimping tool soldering iron and resin core solder clamps(for dialysis tubing) sandpaper or steel wool

Modifications/Substitutions :

• Copper sulfate pentahydrate is available as root killer at garden supply stores. It may also be purchased from pool supliers.
• Aluminum, from aluminum cans, may be used if it is sanded well on both sides. Aluminum gutter nails may also be used.
• Copper tubing or fittings may be used in place of copper strips.
• Zinc can be obtained from old dry cell battery casings. This should be done carefully to avoid contact with caustic chemicals in battery. Small zinc electrodes are available at MiniScience.com and as a part of their Make Electricity Science set.
• Sausage casings can be used in place of dialysis tubing but diffusion is extremely rapid. Dialysis tubing is readily available in biology labs.
• Baby food jars or other open glass jars may be used instead of beakers.

Dialysis tubing is actually a semi-permeable membrane when used in water. This tubing usually comes in rolls and when wet, will open up into a cylindrical tube that can be tied off at the ends. The tubing is usually available at different diameters from 1 cm up to 10 cm.

Any diameter from 3 to 7 cm is good for this experiment.

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.

Calculations:

Description

Summary of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.

Conclusion:

Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

• What material can be used as a membrane in a voltaic cell?
• What salts can be used as electrolyte?
• How does the distance between electrodes affect the voltage?

Possible Errors:

• The metal strips used in this experiment should have a large surface area to minimize resistance within the cell. (I recommend a surface area of 15 square inches or more.)
• Use a voltmeter instead of the light bulb to detect small amounts of electricity.
• Aluminum strips may not work unless sanded thoroughly and acid treated with 6.0 M HCl.
• Use a lamp holder for a secure connection with light bulb and eliminating the need to do soldering.

References:

Summerlin, L.R., and Ealy, J.L. Jr, Chemical Demonstrations-A Sourcebook for Teachers , American Chemical Society, Washington D.C, 1985, p. 115. This experiment is adapted from this source.

http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/electrochem.html

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Lemon Battery Experiment

The lemon battery experiment is a classic science project that illustrates an electrical circuit, electrolytes, the electrochemical series of metals, and oxidation-reduction (redox) reactions . The battery produces enough electricity to power an LED or other small device, but not enough to cause harm, even if you touch both electrodes. Here is how to construct a lemon battery, a look at how it works, and ways of turning the project into an experiment.

Lemon Battery Materials

You need a few basic materials for a lemon battery, which are available at a grocery store and hardware store.

• Galvanized nail
• Copper penny, strip, or wire
• Wires or strips of aluminum foil
• Alligator clips or electrical tape
• An LED bulb, multimeter, digital clock, or calculator

If you don’t have a lemon, use any citrus fruit. A galvanized nail is a steel nail that is plated with zinc. The classic project uses copper and zinc because these two metals are inexpensive and readily available. However, you can use any two conductive metals, as long as they are different from each other.

Make a Lemon Battery

• Gently squeeze the lemon or roll it on a table to soften it. This helps the juice flow within the fruit.
• Insert the copper and zinc into the fruit. You want the maximum surface area in the juicy part of the fruit. The lemon peel helps support the metal, but if it is very thick and the metal does not reach the juice, scrape away part of the peel. Ideally, separate the metal pieces by about 2 inches (5 centimeters). Make sure the metals are not touching each other.
• Connect a wire to the galvanized nail using an alligator clip or electrical tape. Repeat the process with the copper item.
• Connect the free ends of the wire to an LED or other small electronic device. When you connect the second wire, the light turns on.

Increase the Power

The voltage of a lemon battery is around 1.3 V to 1.5 V, but it generates very little current. There are two easy ways of increasing the battery’s power.

• Use two pennies and two copper pieces in the lemon. You don’t want any of the metal pieces within the fruit to touch. As before, connect one zinc and one copper piece to the LED. But, wire the other zinc and copper to each other.
• Wire more lemons in series with each other. Insert a nail and copper piece into each nail. Connect the copper of one lemon to the zinc of the next lemon. Connect the nail at the end of the series to the LED and the copper at the end of the series to the LED. If you don’t have lots of lemons, you can cut up one lemon into pieces.

How a Lemon Battery Works

A lemon battery is similar to Volta’s first battery, except he used salt water instead of lemon juice. The zinc and copper are electrodes. The lemon juice is an electrolyte . Lemon juice contains citric acid. While both salts and acids are examples of electrolytes, acids typically do a better job in batteries.

Connecting the zinc and copper electrodes using a wire (even with an LED or multimeter between them) completes an electrical circuit. The circuit is a loop through the zinc, the wire, the copper, and the electrolyte, back to the zinc.

Zinc dissolves in lemon juice, leaving zinc ions (Zn 2+ ) in the juice, while the two electrons per atom move through the wire toward the copper. The following chemical reaction represents this oxidation reaction :

Zn → Zn 2+  + 2e −

Citric acid is a weak acid, but it partially dissociates and leaves some positively charged hydrogen ions (H + ) in the juice. The copper electrode does not dissolve. The excess electrons at the copper electrode combine with the hydrogen ions and form hydrogen gas at the copper electrode. This is a reduction reaction.

2H + + 2e −  → H 2

If you perform the project using lemon juice instead of a lemon, you may observe tiny hydrogen gas bubbles forming on the copper electrode.

Try Other Fruits and Vegetables

The key for using produce in a battery is choosing a fruit of vegetable high in acid (with a low pH). Citrus fruits (lemon, orange, lime, grapefruit) contain citric acid. You don’t need a whole fruit. Orange juice and lemonade work fine. Potatoes work well because they contain phosphoric acid. Boiling potatoes before using them increases their effectiveness. Sauerkraut contains lactic acid. Vinegar works because it contains acetic acid.

Experiment Ideas

Turn the lemon battery into an experiment by applying the scientific method . Make observations about the battery, ask questions, and design experiments to test predictions or a hypothesis .

• Experiment with other materials for the electrodes besides a galvanized nail and copper item. Other common metals available in everyday life include iron, steel, aluminum, tin, and silver. Try using a nickel and a penny. What do you think will happen if you use two galvanized nails and no copper, or two pennies and no nails? What happens if you try to use plastic, wood, or glass as an electrode? Can you explain your results?
• If you have a multimeter, explore whether the distance between the electrodes affects the voltage and current of your circuit.
• How big is the effect of adding a second lemon to the circuit? Does it change the voltage? Does it change the current?
• Try making batteries using other foods from the kitchen. Predict which ones you think will work and test them. Of course, try fruits and vegetables. Also consider liquids like water, salt water, milk and juice, and condiments, like ketchup, mustard, and salsa.

The lemon battery dates back to at least 2000 years ago. Archaeologists discovered a battery in Iraq using a clay pot, lemon juice, copper, iron, and tar. Of course, people using this battery did not know about electrochemistry or even what electricity was. The use of the ancient battery is unknown.

Credit for discovery of the battery goes to Italian scientists Luigi Galvani and Alessandro Volta. In 1780, Luigi Galvani demonstrated copper, zinc, and frog legs (acting as an electrolyte) produced electricity. Galvani published his work in 1790. An electrochemical cell is called a galvanic cell in his honor.

Alessandro Volta proved electricity did not require an animal. He used brine-soaked paper as an electrolyte and invented the voltaic pile in 1799. A voltaic pile is a stack of galvanic cells, with each cell consisting of a metal disk, an electrolyte layer, and a disk of a different metal.

• Goodisman, Jerry (2001). “Observations on Lemon Cells”. Journal of Chemical Education . 78(4): 516–518. doi: 10.1021/ed078p516
• Margles, Samantha (2011). “ Does a Lemon Battery Really Work? “. Mythbusters Science Fair Book . Scholastic. ISBN 9780545237451.
• Naidu, M. S.; Kamakshiaih, S. (1995). Introduction to Electrical Engineering . Tata McGraw-Hill Education. ISBN 9780074622926.
• Schmidt, Hans-Jürgen; Marohn, Annette; Harrison, Allan G. (2007). “Factors that prevent learning in electrochemistry”. Journal of Research in Science Teaching . 44 (2): 258–283. doi: 10.1002/tea.20118
• Swartling, Daniel J.; Morgan, Charlotte (1998). “Lemon Cells Revisited—The Lemon-Powered Calculator”. Journal of Chemical Education . 75 (2): 181–182. doi: 10.1021/ed075p181

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Hands-on Activity Mission Possible - The Voltaic Protocol

Grade Level: 11 (10-12)

(Time can also be split into two 45-minute periods.)

Expendable Cost/Group: US $15.00

Group Size: 3

Activity Dependency: None

Subject Areas: Chemistry, Physics, Science and Technology

NGSS Performance Expectations:

TE Newsletter

Engineering connection, learning objectives, materials list, worksheets and attachments, more curriculum like this, pre-req knowledge, introduction/motivation, vocabulary/definitions, investigating questions, troubleshooting tips, activity extensions, activity scaling, additional multimedia support, user comments & tips.

Chemical and environmental engineers are constantly being challenged to develop new technologies to generate energy and power from limited resources, sometimes including the challenge of self-sustaining technologies. There is also a need to find ways to improve the overall performance of existing technologies without some of the harmful effects from long-term exposure to extreme environmental temperatures. This activity pertains to real-world engineering in challenging students to create a properly operating galvanic cell from a list of given materials and develop a method to optimize this system under various environmental conditions.

After this activity, students should be able to:

• Identify the reactants and products of a chemical reaction.
• Describe how a galvanic cell transforms chemical energy into electrical energy.
• Use a galvanic cell to power a device within a simple or complex electrical circuit.
• Use the scientific method to solve a problem within specific qualitative and quantitative constraints.

Educational Standards Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards. All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN) , a project of D2L (www.achievementstandards.org). In the ASN, standards are hierarchically structured: first by source; e.g. , by state; within source by type; e.g. , science or mathematics; within type by subtype, then by grade, etc .

Ngss: next generation science standards - science.

State Standards

Texas - science.

View aligned curriculum

Do you agree with this alignment? Thanks for your feedback!

Each group will need:

• safety goggles (one pair per student)
• gloves (one pair per student)
• 2 beakers (500 ml)
• graduated cylinder (250 ml)
• copper sulfate (CuSO 4 ) solution (1.0M, 250 mL)
• zinc sulfate (ZnSO 4 ) solution (1.0M, 250 mL)
• 2-4 pieces of electrical wiring each with alligator clips
• strip of copper metal (long enough to sit half submerged in the 250 mL copper sulfate solution)
• strip of zinc metal (long enough to sit half submerged in the 250 mL zinc sulfate solution)

Salt Bridge

• sodium chloride (NaCl) solution (50 mL)
• pipette (plastic or glass)
• 20-cm filter paper strips OR filter paper folded to ~1 cm thick and long enough to touch the liquids in each 250 mL beaker
• How to Create a Galvanic Cell Student Handout (one per student)
• How to Create a Galvanic Cell Student Worksheet (one per student)
• battery-powered device to test (such as a LED-emitting light, clock, simple motor, etc.) Note: In theory, any battery-operated device should work. However, it is important to think about the amount of voltage that's required to power the device and how easily it can be accessed using simple wiring from the voltaic cell. Ideally, a small light bulb or a small buzzer or alarm are useful because they already have a way to easily connect to the alligator clips or any other existing wires, and they don't require a lot of voltage to power them. Buzzer alarms are available on Amazon at a low cost.

For the class to share:

• computer with projector to display video.
• waste containers for byproducts of chemical reactions (metal ion waste solutions)

Students will need a basic understanding of chemical reactions and redox reactions. A galvanic or voltaic cell uses a redox reaction as its primary source of energy.  They will also need to know how a galvanic cell operates and how to create an electrical circuit.

Today, let’s assume the role of a real-life engineer attempting to solve a real-world problem! Our reliance on the convenience of electronic devices has created a huge demand for better batteries that can last longer. From cell phones to electric vehicles, society has started to utilize rechargeable batteries of every form and fashion. However, one of the disadvantages of using rechargeable batteries relates to the need for electrochemical and physical resources to maintain supply to meet demand with limited resources. Is this a “mission impossible” or can we solve this engineering challenge? Let’s find out!

Your mission, should you choose to accept it, is to create an electrochemical cell similar to the environment inside of a rechargeable battery with limited resources. Your cell must be self-sustaining, and it should serve as a reliable source of energy for whatever device that is presented to your group.

What is a galvanic cell and how does it work? A galvanic (or voltaic) cell is a type of electrochemical cell that utilizes chemical reactions to produce electrical energy. Specifically, these chemical reactions can be further classified as oxidation-reduction reactions. An oxidation-reduction reaction, or redox for short, is a type of reaction whereby electrons are transferred via a series of steps which can be referred to as half-reactions. During the oxidation half-reaction an element will undergo a process resulting in an overall loss of electrons. The reduction half-reaction will result in an element that undergoes an overall gain of electrons. This process of electron transfer is more discernible in some redox reactions in comparison to others. The unique properties of a galvanic cell will separate these half-reactions from one another, thus allowing an electrical current to flow through conductive material. This electrical current can then be made available to produce electrical energy.

To successfully create a galvanic cell, the most essential components should include two metal ion solutions of a given concentration and a salt bridge that connects these two solutions to one another. These metal ion solutions could include sulfates, nitrates, etc.

The cell reaction is:

 Zn (s) + Cu 2+ (aq) --> Zn 2+ (aq) + Cu (s)

Before the Activity

• Gather materials and make copies of the How to Create a Galvanic Cell Student Handout and How to Create a Galvanic Cell Student Worksheet

With the Students

• Divide students into groups of three or four students for each lab station.
• Hand out group materials or have group materials distributed to each lab station ahead of time.
• Each group should first draw a schematic of their galvanic cell and how they will create a circuit using their cell to power their given device. Each group should show their schematic to the instructor first to get approval before starting actual construction. 

• Using the supplied materials and their schematic to make their galvanic cells, have students follow the step-by-step directions on the How to Create a Galvanic Cell Student Handout . The directions are:
• Pour 250 ml of copper sulfate and 250 ml of zinc sulfate solution into two separate 500 ml beakers.
• Place a strip of copper metal into the copper sulfate solution and a strip of zinc metal into the zinc sulfate solution. This will begin the oxidation-reduction reaction process.
• Create a salt bridge between the two solutions by soaking the piece of filter paper with the sodium chloride solution. After soaking the filter paper with sodium chloride, position your paper so that each end of filter paper is in contact with the two separate solutions. [The How to Create a Galvanic Cell Student Worksheet includes an example to show this setup.]
• Allow the reaction a few minutes to begin. After a few minutes use the voltmeter to test the voltage of the cell by placing an electrode on each end of the two metal strips.
• Once confirmation is received that the cell is producing a potential difference, create a circuit based upon your schematic using your wiring, alligator clips, and your given device.
• Attempt to power your device using your galvanic cell. If your device will not power on you may need to add an additional cell to your circuit to generate more voltage.
• Once the activity is completed clean up your work area and dispose of waste materials following the given lab safety protocols for your station.
• Actively monitor progress for each group during the construction process.
• Once a group of students have successfully created their galvanic cell, provide the group with the electrical circuit materials and the device that they must use their cell to power and/or operate.
• Students will connect alligator clips from their cell to their device to attempt to power it.
• After successfully powering the device, have students answer the post-lab discussion questions in the How to Create a Galvanic Cell Student Worksheet
• Provide students with time to fill out the Student Self-Assessment Rubric discussing what was learned from the activity, what were possible sources of error, and how the activity could be improved upon in the future.

anode: An electrode through which the conventional current enters into a polarized electrical device.

cathode: An electrode through which conventional current leaves an electrical device.

galvanic cell: A galvanic cell or voltaic cell, named after the scientists Luigi Galvani and Alessandro Volta, respectively, is an electrochemical cell in which an electric current is generated from spontaneous reactions. A common apparatus generally consists of two different metals, each immersed in separate beakers containing their respective metal ions in solution that are connected by a salt bridge (or separated by a porous membrane).

oxidation: Oxidation can be considered as an addition of an oxygen atom to a compound.

redox reaction: A type of chemical reaction in which the oxidation states of atoms are changed.

reduction: A chemical species decreases its oxidation number, usually by gaining electrons.

salt bridge: A tube containing an electrolyte (typically in the form of a gel), providing electrical contact between two solutions.

Pre-Activity Assessment

Battery Brainstorming: Place students in small groups and allow each group time to brainstorm ideas about how a battery works and why chemistry is such an important part of a battery’s function. An online polling program or a whiteboard could be used to allow students to present their prior knowledge, discuss ideas, and address possible misconceptions.

Potential pre-assessment questions could include:

• How do batteries use chemicals to generate power? (Answer: A chemical reaction between the metals and the electrolyte frees more electrons in one metal than it does in the other. The metal that frees more electrons develops a positive charge, and the other metal develops a negative charge.)
• What is a galvanic cell? (Answer: Galvanic cells, also known as voltaic cells, are electrochemical cells in which spontaneous oxidation-reduction reactions produce electrical energy.)
• What is an oxidation-reduction reaction? (Answer: A redox reaction is an oxidation-reduction (redox) reaction is a type of chemical reaction that involves a transfer of electrons between two species.)
• What is a series circuit? (Answer: a series circuit is defined as having only one path through which current can flow.)
• Why does a battery eventually stop providing power over time? (Answer: This wearing out process is due to the chemical reaction between the ions and the electrolyte. Some have described it as a parasitic reaction. To keep it simple, the ions do not move as freely the older the battery gets. Once they stop moving back and forth, the battery is officially dead.)

Activity Embedded (Formative) Assessment

Handout: Ensure that students are following the directions on the How to Create a Galvanic Cell Student Handout . Check that they are accurately drawing a diagram of their galvanic cell and answering the discussion questions. 

Post-Activity (Summative) Assessment

Post-Lab Discussion: After students complete the post-lab discussion questions on the How to Create a Galvanic Cell Student Handout , have a class discussion about the activity.

Student Self-Assessment: Monitor students as they complete the activity. Distribute the Student Self-Assessment Rubric . Students complete this rubric to reflect on where they think their understanding lies for each success criteria. Use this as a starting-point for a class discussion about the activity.

Check for Understanding: Distribute the How to Create a Galvanic Cell Student Worksheet . Have students complete the multiple-choice questions and use the How to Create a Galvanic Cell Student Worksheet Answer Key to check for their mastery of the material.

• Why is an electrolyte solution needed in a battery? (Answer: Electrolyte serves as catalyst to make a battery conductive by promoting the movement of ions from the cathode to the anode on charge and in reverse on discharge.)
• What is an electrochemical cell? (Answer: An electrochemical cell is a device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions.)
• What is the difference between exothermic and endothermic reactions? (Answer: An exothermic process releases heat, causing the temperature of the immediate surroundings to rise. An endothermic process absorbs heat and cools the surroundings.)
• What is a redox reaction and how does it create energy? (Answer: A redox reaction is an oxidation-reduction (redox) reaction is a type of chemical reaction that involves a transfer of electrons between two species. In redox reactions, energy is released when an electron loses potential energy as a result of the transfer.)
• What is the difference between a simple or complex circuit? (Answer: Light bulbs are used in simple circuits whereas, in complex bigger circuits, the load can be a combination of various other electronic components such as capacitors, resistors, transistors etc. There are different types of circuits; the two basic ones are series and parallel circuits.)
• How is chemical energy converted into electrical energy? (Answer: A battery is a device that stores chemical energy and converts it to electrical energy. The chemical reactions in a battery involve the flow of electrons from one material (electrode) to another, through an external circuit. The flow of electrons provides an electric current that can be used to do work.)

Safety Issues

• Eye protection should be included due to the need to work with redox reactions and exothermic processes.
• Waste containers should be provided for byproducts of chemical reactions (metal ion waste solutions).
• Students will be working with small amounts of electrical current.

Some issues or obstacles that could occur during this exercise could include a failure of galvanic cell to generate enough current to light bulbs, the salt bridge could malfunction, or chemical solutions improperly leaking into or out of containers.  Ways to monitor and fix this is to possibly have pre-built galvanic cells for the students in case their attempts do not work. Having more than one cell pre-built will help give students multiple attempts to try the experiment again without wasting too much time. Another issue could also arise from not having enough sulfate solution in each beaker. This could hinder the flow of electrons and hinder the flow of electrical current in the circuit. To solve this enough sulfate solution should be provided and prepared ahead of time so that each group can submerge both metal strips in their respective solution to at least cover the bottom 1/3 of each metal strip.

As an extension, students could be provided with different metal ion solutions to power their cells and compare cell efficiency and the amount of voltage produced to their initial experiment. Students could also brainstorm on how their voltaic cell could be expanded to power larger devices or multiple devices at the same time. 

Ways to adjust this activity for different grade levels could include:

• Lower grades and younger students: have students create voltaic cells out of more simple materials and/or household supplies such as vinegar, copper coins, aluminum foil, cotton balls, and a small device with wire leads to connect a circuit. Students can be evaluated on how quickly they assemble the cell and on their understanding of how the cell works.
• Upper grades and more advanced students: have students substitute different metals to see which metals work best for the redox process. Allow students to discover that some metals are less efficient than others for the reaction process. Students could also be challenged to power different types of devices that require multiple cells connected in a series or in parallel.  

The following are possible challenges and distractions that could be used during this activity to give the students an extra challenge. This is to stay true to the mission impossible theme of teams of agents which may face an enemy or unexpected obstacle while attempting to complete their mission. The practical application of this to the real world could be how a problem or project is presented to a team of engineers and that team must decide on the best method on how to solve this problem or how to complete this project. Logistics for a solution must include time, available resources, and budget constraints. Unexpected delays or obstacles should also factor into completion of projects. (For example, how the pandemic has led to a global semi-conductor chip shortage which has in turn affected production in multiple areas of technology from personal computers to the automotive industry) 

Using these challenges and distractors not only adds a little more excitement into the activity but it also gives students a chance to experience some of the challenges that an engineering team may face while trying to complete a project in the real world.

As a suggestion, allow groups to do the activity for the first time without a challenge or distraction in order to become comfortable with the process of how to create the cell. Afterwards have students do the activity a second time with the challenge and/or distractors. The moment that distractors or challenges will be utilized could also be announced to the groups as a means of adding suspense and/or excitement to the activity. A group of helpers/students assisting with implementing these challenges or distractors could then walk into the room wearing suits and sunglasses with fanfare or given some type of dramatic introduction. (i.e.:” Oh no. Who is this? Who are these people? Here come the enemy agents! What are they going to do? Everyone prepare yourself because they’re definitely up to no good!)

Possible challenges to use for each group or multiple groups:

• Have students create another voltaic cell but this time they must use half of the supplies that they were given at the beginning.
• Give students a device to power with their voltaic cell but the device will require a larger amount of voltage. (So they may need to create more than one voltaic cell and decide how to add it to their circuit(s))
• Create a voltaic cell with household supplies instead of the standard chemistry laboratory supplies that were given at the beginning of the activity.

(Supplies for this household cell could include: vinegar, copper pennies, aluminum foil, electrical wiring with alligator clips, cotton balls, and a simple light bulb with its holder. Providing various supplies for this challenge will allow students to be more creative in designing a simple cell)

Distractors – The following options could be used to distract students from completing their goal. This is meant to simulate enemy agents or some type of unexpected obstacle that an agent may face while on their mission.

• Use party horns and walk around each group of students to distract them from their work.
• Use a portable stereo to play annoying or distracting songs or music while a group is working. This shouldn’t be interpreted, however, as offensive music or playing songs at extreme volume. One way to find possible options for this distraction is to do a poll prior to the activity asking each student or group about their most annoying song. Once students have revealed their most unlikeable songs they could be played for those students during the activity.
• Randomly walk up to a group of students and take away an essential supply that is needed to complete their lab activity.
• Purposely give a group of students a false chemical and allow students a chance to figure out what is wrong. For example, substitute the salt solution with a deionized water solution instead. (Caution should be used with this distraction to make sure nothing is used which could cause a harmful reaction during the activity)

Once implementing the distractors within the activity provide students will a solution to these problems with a box labeled “countermeasures”. Each box of countermeasures could include: earplugs to help with the annoying music or party poppers, aluminum foil with electrical tape so that students can create their own wiring in place of any stolen electrical wiring, and substitute ion solutions that can replace any confiscated copper and zinc sulfate solutions.

Information about Galvanic Cells and Cell Potential – LibreTexts Chemistry:

https://chem.libretexts.org/Bookshelves/General_Chemistry/Book%3A_Chem1_(Lower)/16%3A_Electrochemistry/16.02%3A_Galvanic_cells_and_Electrodes

How to make a simple galvanic cell – STEM Learning: https://www.youtube.com/watch?v=IUpOht-1g0s

Electrochemistry and Voltaic Cells – METUOpenCourseWare: https://www.youtube.com/watch?v=afEX2FD4Ado

Technical Resource on Galvanic Cells – ScienceDirect: https://www.sciencedirect.com/topics/engineering/galvanic-cell

Making and Testing a Simple Galvanic Cell – Science Project: https://www.scienceprojects.org/making-and-testing-a-simple-galvanic-cell/

This lab exercise exposes students to a potentially new alternative energy source—hydrogen gas. Student teams are given a hydrogen generator and an oxygen generator. They balance the chemical equation for the combustion of hydrogen gas in the presence of oxygen.

Students learn about current electricity and necessary conditions for the existence of an electric current. Students construct a simple electric circuit and a galvanic cell to help them understand voltage, current and resistance.

Students learn and discuss the advantages and disadvantages of renewable and non-renewable energy sources. They also learn about our nation's electric power grid and what it means for a residential home to be "off the grid."

Students learn that charge movement through a circuit depends on the resistance and arrangement of the circuit components. In one associated hands-on activity, students build and investigate the characteristics of series circuits. In another activity, students design and build flashlights.

Summerlin, L.R., and Ealy, J.L. Jr, Chemical Demonstrations-A Sourcebook for Teachers, American Chemical Society, Washington D.C, 1985, p. 115.

Science Project. Making and Testing a Simple Galvanic Cell. https://www.scienceprojects.org.

Contributors

Supporting program, acknowledgements.

This activity was developed under the National Science Foundation under Rice University Engineering Research Center for Nanotechnology Enabled Water Treatment Systems (NEWT) grant no.1449500. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

Special thanks to Dr. Quilin Li, Dr. Carolyn Nichol, Dr. John Ramon, Yuren Feng, Christina Alston and Isaias Cerda.

Last modified: October 11, 2022

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Shop Experiment Establishing a Table of Reduction Potentials: Micro-Voltaic Cells Experiments​

Establishing a table of reduction potentials: micro-voltaic cells.

Experiment #28 from Chemistry with Vernier

Introduction

The main objective of this experiment is to establish the reduction potentials of five unknown metals relative to an arbitrarily chosen metal. This will be done by measuring the voltage, or potential difference, between various pairs of half-cells.

A voltaic cell utilizes a spontaneous oxidation-reduction reaction to produce electrical energy. Half-cells are normally produced by placing a piece of metal into a solution containing a cation of the metal (e.g., Cu metal in a solution of CuSO 4 or Cu 2+ ). In this micro-version of a voltaic cell, the half cell will be a small piece of metal placed into 3 drops of solution on a piece of filter paper. The solution contains the cation of the solid metal. The half-cells will be arranged on a piece of filter paper. The two half-reactions are normally separated by a porous barrier or a salt bridge. Here, the salt bridge will be several drops of aqueous NaNO 3 placed on the filter paper between the two half cells. Using the computer as a voltmeter, the (+) lead makes contact with one metal and the (–) lead with another. If a positive voltage is recorded on the screen, you have connected the cell correctly. The metal attached to the (+) lead is the cathode (reduction) and thus has a higher, more positive, reduction potential. The metal attached to the (–) lead is the anode (oxidation) and has the lower, more negative, reduction potential. If you get a negative voltage reading, then you must reverse the leads.

By comparing the voltage values obtained for several pairs of half-cells, and by recording which metal made contact with the (+) and (–) leads, you can establish the reduction potential sequence for the five metals in this lab.

In this experiment, you will establish the reduction potentials of five unknown metals relative to arbitrarily chosen metal.

Sensors and Equipment

This experiment features the following sensors and equipment. Additional equipment may be required.

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This experiment is #28 of Chemistry with Vernier . The experiment in the book includes student instructions as well as instructor information for set up, helpful hints, and sample graphs and data.