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Comparing Batteries Made from Different Citrus Fruits Mark as Favorite (0 Favorites)

LAB in Electricity, Galvanic Cells, Graphing. Last updated February 14, 2025.

Summary

In this lab, students will explore and compare how different citrus fruits can be used to make batteries. Student lab groups will collect the voltage data for batteries made from limes, lemons, oranges, and grapefruit, then determine if there is a difference in the voltage they can produce.

Grade Level

Middle or High School

NGSS Alignment

This lab will help prepare your students to meet the performance expectations in the following standards:

  • MS-ETS1-3: Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success.
  • Scientific and Engineering Practices:
    • Asking Questions and Defining Problems
    • Analyzing and Interpreting Data

Objectives

By the end of this lab, students should be able to

  • Understand the relationship between the number of cells and the voltage of simple galvanic batteries.
  • Plot data sets correctly on a graph, then analyze the data for trends and to draw conclusions.

Chemistry Topics

This lab supports students’ understanding of

  • Electrochemistry
  • Electricity
  • Electrolytes
  • Galvanic cells
  • Graphing

Time

Teacher Preparation: 45 minutes
Lesson: 60 minutes

Materials (per group)

  • 5 pieces of each assorted citrus fruits (lemons, limes, oranges, grapefruit)
  • Copper (wire or clean pennies)
  • Zinc Metal (wire, nails, or washers)
  • Paper towels
  • Wire Cutter (if using wire)
  • Knife or scissors
  • 6 Alligator Clips
  • Multimeter
Materials for citrus fruit battery experiment

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Students should wash their hands thoroughly before leaving the lab.
  • When students complete the lab, instruct them how to clean up their materials.
  • Make sure that the multimeter is in good working condition.
  • Be careful if you are using a knife or scissors tip to cut a slit in the fruit.
  • Do not construct the fruit battery near a heat source or flame.

Teacher Notes

  • If you use different citrus fruits than those indicated in the background information, test them before having students work with them.
  • Break students into several groups and assign each group a different type of citrus fruit. They will build batteries using one, two, three, four, and five pieces of fruit. They will then compare data and create graphs of voltage versus the number of pieces of fruit.
  • All the fruits in this lab contain citric acid, which is an electrolyte. Citric acid is a weak acid that does not completely dissociate, but positive hydrogen ions and negative citrate ions will be present in solution (juice).
  • The fruits used should not be hard. You may want to microwave the fruit for a few seconds and have students roll the fruit around to make it juicier.
  • If possible, it is best to have a multimeter for each group. There are several low cost meters sold by Amazon.
    • If you are not familiar with using the multimeter, refer to the video tutorial from Science Buddies “How to Use a Multimeter”.
  • Students should follow the part 1 procedures to fully prepare the equipment so that they can work quickly to measure the voltage after the addition of each piece of fruit.
  • When the preparation steps are completed, data collection can begin.
  • If possible, have a digital shared group document that students can use to report their data. If that’s not possible, have a master data table in a central location for students to record their data.
  • After all the data is collected, students can graph the data and draw conclusions from the results.
  • If you have access to small, red LED lights you can have students add them to the final circuit so that they can see the bulb light.
  • The LED lightbulb has two wire electrodes. The alligator clip from the copper metal should be attached to the long LED electrode. The alligator clip from the zinc metal should be attached to the short LED electrode.
  • An Answer Key document has been included with expected results for teacher reference.

For the Student

Overview

In this lab activity you will explore and compare how different citrus fruits can be used to make batteries. Your group will receive five pieces of the same type of citrus fruit to construct a battery. You will collect voltage data for a battery made from either limes, lemons, oranges, or grapefruit, then use the data to construct a graph and calculate the change in voltage for each type of fruit.

Materials

  • 5 pieces of citrus fruits (either lemons, limes, oranges, or grapefruit)
  • Copper (wire or clean pennies)
  • Zinc Metal (wire, nails, or washers)
  • Paper towels
  • Knife or scissors
  • 6 Alligator Clips
  • Multimeter

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Wash your hands thoroughly before leaving the lab.
  • Follow your teacher’s instructions for cleanup of materials.
  • Make sure that the multimeter is in good working condition.
  • Be careful if you are using a knife or scissors tip to cut a slit in the fruit.
  • Do not construct the fruit battery near a heat source or flame.

Procedures

Part 1: Preparation

  1. Carefully follow instructions to prepare your station before you begin to build your battery. This will allow you to efficiently build the battery and measure the voltage.
  2. Collect five pieces of the same type of citrus fruit (lemon, lime, oranges, or grapefruit).
  3. Identify one group member to record the voltage (V) of each circuit constructed on the data table in the lab handout.
  4. Check the fruit. It should not be hard. If it is, roll each piece around on a table to create more juice. If possible, microwave each piece of fruit for a few seconds before rolling it on the table.
  5. Wash and dry your fruit with paper towels before you begin.
  6. Insert a piece of copper metal and a piece of zinc metal on opposite sides of each piece of fruit. See photo. If necessary, use a knife or the tip of scissors to puncture a small hole for each metal.
  7. Don’t make the hole too big. This will cause the juice to leak out of the fruit.
  8. Organize the pieces of fruit in a circular shape with the zinc metal of one fruit facing the copper metal of the next fruit.
  9. When the fruit pieces are properly prepared, attach an alligator clip to each of the zinc metal pieces.
  10. Place another alligator clip next to each piece of fruit. It will be attached to the copper metal pieces when your group starts collecting data with the multimeter.

Part 2: Data Collection

Measuring voltage with citrus battery>
  1. Turn on the multimeter. Turn the dial to measure volts (V) and select 20.
  2. Connect an alligator clip to the copper metal on the first piece of fruit.
  3. Measure the voltage by touching the alligator clip connected to the copper with the red electrode and the alligator clip connected to the zinc with the black electrode.
  4. Record the voltage when it stops changing in the data table for the correct type of fruit, in the “1 piece” row.
  5. Quickly connect the alligator clip on the zinc metal on the first fruit to the copper metal on the second fruit.
  6. Touch the alligator clip attached to the copper metal of the first fruit with the red electrode and the alligator clip connected to the zinc metal of the second fruit to the black electrode.
  7. Record the voltage when it stops changing in the data table for the correct type of fruit, in the “2 piece” row.
  8. Repeat this process for a circuit made from 3, 4, and 5 pieces of fruit.
  9. Share your data with the class data table.
  10. When all the groups have finished, visit each of the other stations and observe the results for other types of fruit.
  11. Disassemble your circuit, clean all parts with water, and place them on paper towels to dry.

Data

Voltage

Type of Citrus Fruit

Lemons

Limes

Oranges

Grapefruit

1 piece

2 pieces

3 pieces

4 pieces

5 pieces

Graph the Data

Use the graph paper below or Excel to prepare a graph of voltage versus the number of pieces of fruit.

  • Put all of the different types of fruit on one graph (use a different color for each type of fruit).
  • Be sure to include a title, a label for each axis, and numbering on each axis.
  • Create a key to show the type of fruit used for each plot.

Questions

Use your data and graphs to answer the following questions. Show all of your work.

  1. Look at the data for the lemons. Calculate how much the voltage increased each time another lemon was added.
  2. Look at the data for the limes. Calculate how much the voltage increased each time another lime was added.
  3. Look at the data for the oranges. Calculate how much the voltage increased each time another orange was added.
  4. Look at the data for the grapefruit. Calculate how much the voltage increased each time another grapefruit was added.
  5. Which fruit had the highest voltage?
  6. Which fruit had the lowest voltage?
  7. Are the graphs you drew linear (or close to linear)?
  8. Can you think of a reason the graphs are not completely linear?