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Chemistry of Art through Alloys and Metal Plating Mark as Favorite (2 Favorites)

LAB in Physical Properties, Molecular Structure, Alloys. Last updated July 20, 2022.


Summary

In this lab, students will learn about and experiment with the process of electroless chemical plating in order to create a piece of artwork made from a combination of copper, zinc-plated copper, and brass.

Grade Level

High School

NGSS Alignment

This lab 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.
  • HS-PS2-6: Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials.
  • Scientific and Engineering Practices:
    • Planning and Carrying Out Investigations

Objectives

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

  • Differentiate between copper, zinc-plated copper and brass.
  • Comprehend how to plate metal using an electroless chemical process.
  • Explain the concept of alloys and how they are formed.

Chemistry Topics

This lab supports students’ understanding of

  • Alloys
  • Metal Plating
  • Molecular Structure
  • Physical Properties
  • Chemical Reactions

Time

Teacher Preparation: 45-60 minutes
Lesson: 150 minutes

Materials

  • *Copper metal foil approximately 4” x 4” (example from Amazon)
  • *Wood square approximately 4” x 4” (example from Amazon)
  • Zinc sulfate (approximately 30 grams)
  • Zinc metal, mossy
  • Tap water
  • 2 - 250 mL beakers
  • Electronic balance
  • Dixie cups or weighing Boat
  • Hot plate
  • Stirring rod
  • Tweezers
  • Scissors
  • Self-Drying Gorilla Glue

(*asterisks denote items needed per student)

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 and dispose of any chemicals.
  • Exercise caution when using a heat source. Hot plates should be turned off and unplugged as soon as they are no longer needed.
  • An operational fire extinguisher should be in the classroom.
  • Reference the SDS for zinc sulfate for additional information.

Teacher Notes

  • In this lab activity, students will work independently to create their own piece of artwork but can share some lab equipment (electronic balance, hot plates, etc.). Pairs of students can work together to create and share each zinc sulfate solution.   
  • Each student should be given a piece of copper foil (approximately 4” x 4”) and instructed to cut out at least three parts that will make up whatever shape/object/design they choose.
  • Students can create a 3-D or 2-D design using at least 3 separate pieces of metal cut from their original piece of copper. Students should plan to incorporate different colored pieces of metal into their design (which they will determine/make through the lab process). See examples shown in the photos below.
  • They will then plate at least two pieces with zinc metal using an electroless chemical plating process. After that, students will heat at least one of the plated metal pieces to change it into brass. Finally, they will mount their metal foil pieces to a wood square (approximately 4” x 4”) using gorilla glue to create their final piece of artwork.
  • When beginning to design their artwork, students should use a tool that has a hard edge (like a wood stick or the back of a pen) to make a design on the copper. Then they will cut out the pieces using scissors.
  • During the zinc-plating process, if the copper pieces aren’t turning silvery-grey colored within 15-20 minutes, remove the pieces and dissolve more zinc sulfate (approximately 10 grams). You can also add more mossy zinc to the bottom of the beaker. Be sure to remove the copper pieces before doing either of these troubleshooting steps.
  • Reiterate to students that the copper pieces need to lie flat on the mossy zinc. If more than one piece is in the beaker, be sure that they are not touching or overlapping on top of each other.
  • In order to have three different colored metals in their final design, the students should plan to leave a piece of copper untreated zinc-plate at least two pieces, followed by heating at least one piece that has been zinc-plated.
  • The zinc sulfate solution can be reused for other classes occurring that same day. The solution is supersaturated, so it wouldn’t likely be useable beyond that timeframe. The mossy zinc can be filtered out, washed, dried, and reused from class to class and year after year.
  • Below are photos of the final product from two students. The rosy-colored parts are the original copper metal, the silvery grey-colored parts are zinc plated copper, and the golden yellow-colored parts are the zinc plated copper that has been heated into brass.
  • Students should use epoxy self-drying gorilla glue to paste their copper pieces on wood squares or another sturdy material (like foam board).
  • An Answer Key document has been provided for teacher reference.
  • Several examples of student work are shown below:

For the Student

Background

Metal plating: when one metal is put on the surface of another metal, is very useful to increase the strength of a metal, to prevent corrosion, or maybe just to change the color of metal for designing and decorating purposes. Electroless plating is a way of plating without using an external power source. This plating process involves placing the metal in an aqueous solution of zinc sulfate and depositing zinc metal onto the copper metal, creating a catalytic reduction of zinc ions to plate the piece without any electrical energy dispersal. Unlike electroplating (using electricity to plate metal), this is a purely chemical process with no extra machines or electrical power necessary.  When copper is zinc plated, it will appear to change from its coppery color to a silvery-gray color. By using sufficient heat, zinc-plated copper can be changed to an alloy with a golden color. An alloy is a mixture of elements in which at least one is a metal. There are many different types of alloys. The alloy being made today is called brass, which is a mixture of copper and zinc.

Objective

To understand the process of electroless metal plating and alloys through the preparation of a copper metal foil design.

Pre-Lab Questions

  1. What is an alloy?
  2. What is meant by “plating metal” and what is the purpose of this process?
  3. What is brass?  Why would brass be preferred over copper in the jewelry making process?

Materials (per lab group)

  • Copper metal (approximately 4” x 4”)
  • Wood square (approximately 4” x 4”)
  • A wood stick or hard edge (for metal tooling/designing)
  • Zinc sulfate (approximately 30 grams)
  • Zinc metal, mossy
  • Tap water
  • 2- 250 mL beakers
  • Electronic balance
  • Dixie cups or Weighing boat
  • Hot plate
  • Stirring rod
  • Tweezers
  • Scissors

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Wash your hands thoroughly before leaving the lab.
  • Follow teacher instructions for clean-up of materials and disposal of any chemicals.
  • Exercise caution when using a heat source. Hot plates should be turned off and unplugged as soon as they are no longer needed.
  • An operational fire extinguisher should be in the classroom.

Procedure

  1. Design, tool, and cut out at least three copper pieces.
    1. Design: Think about what shape, animal, or decoration you want to make.
    2. Tool: Use a wood stick or hard edge (like the back of a pen) to make indentations in the copper foil for design purposes.
    3. Cut: Cut your designs into at least three pieces. Decide which pieces you want to remain copper-colored, which pieces you want to be silvery-grey colored (zinc plated), and which pieces you want to be golden-colored (zinc plated and heated into brass).
  2. Fill one 250 mL beaker 3/4 full of tap water and set it aside. This is your rinsing beaker.
  3. Dissolve approximately 30 grams of zinc sulfate in 100 mL of water in the other 250 mL beaker by heating it on a hot plate.
  4. Place the mossy zinc pieces in the beaker with the zinc sulfate solution, enough pieces to completely cover the beaker bottom.
  5. Using tweezers, place one to two copper pieces in the beaker with the zinc, making sure copper pieces touch the mossy zinc but are not touching or overlapping on each other.
  6. Bring solution to low boil for about 10-15 minutes. The copper pieces will slowly turn a silvery-gray color.
  7. Using tweezers, carefully remove the copper pieces from the solution and then rinse and cool them in the rinsing beaker of water. Then dry them with a paper towel.
  8. Repeat this process until all copper pieces that need to be plated are done.
  9. Place at least one silvery-gray copper plated piece directly on a hot plate heated to about 300°C. Watch as the heat mixes the zinc plating with the copper. This will appear as golden in color. Flip the piece over so that both sides look uniform.
  10. Once the copper piece is a golden color, use tweezers to take it off the hot plate and put it into the rinsing beaker for 1-2 minutes to cool. Then dry them off.
  11. Using epoxy self-drying gorilla glue, adhere the metal pieces into the desired design on the wood square. Set aside for drying purposes.

Post-Lab Questions

  1. Describe how you feel the metal plating process went. Explain whether you felt it was simple, challenging, or somewhere in-between.
  1. If you had the opportunity to redo this lab, would you have made any design changes to your design? How could you improve your technique or process? List at least two improvements.
  1. If you did this lab again, would you still choose to turn at least one of the copper pieces into brass or leave them as zinc-coated copper? Explain your thought process.

Conclusion

An overall summary of the lab and concepts covered in the lab should be included.  Sample questions to include in your conclusion: What did you do? What did you find? What do you think your results mean? Someone should be able to read your conclusion and essentially know what you did in the lab and why you did it.

Error Analysis

A minimum of three possible errors are needed. List the errors and how each one affected the outcome/results of your lab to the best of your knowledge. This is the ANALYSIS part of this section and, in grading, is the most important part. Do not include errors that are totally insignificant, as these will not be accepted.