ENGR 101 Electroplating Professor: Dr. A. V. Filippas TA: Umar Hasni Safety: This lab was designed to be safe, but you will be working with electrically conductive components, electric currents, and chemicals. You will be required to be safe with these materials. Unsafe or unprofessional behavior will not be tolerated. Your safety is paramount, and the TAs will not hesitate to stop your work if you do not abide by the safety measures. Summary In this lab, you will be using a copper sulfate and vinegar solution to electroplate graphene filament with copper. You will then use these copper plated filaments to light up an LED. Introduction Electroplating is a process that uses electricity and metal salts to coat a material with metal. The process of electroplating is similar to a battery acting in reverse. The item to be coated is placed into a solution of one or more metal salts. Then the item is connected to an electrical circuit, and becomes the cathode of the circuit. When a direct current is passed through the circuit, the electrons passing through the solution cause a chemical reaction. This metal will deposit on the cathode, covering it in a thin layer of that metal. Figure 1 Electrodeposition Apparatus
Copper sulfate and vinegar Copper sulfate (CuSO4) is the metal salt in the electrolyte which will function as the electroplating material. Dissolving the copper sulfate in vinegar (figure 1) allows electrodeposition to take place. Figure 1 CuSO4 & Vinegar Graphene Filament The filament provided in lab is PLA with added graphene. Due to the added graphene, the filament is capable of conducting a small current through it however, the current is limited due to the resistance of the PLA itself. The conductivity of this filament can be increased by electroplating the filament itself. You will use this filament as your cathode in the electroplating process. Figure 2 Graphene Filament Pencil Lead In order to keep the reaction in check, you will be using pencil lead as the anode in the electroplating process.
Lab Procedure: In this lab, you will be working with an electrically conductive solution and a current source. In order to ensure safety, you will be following the process chart shown below: After arriving in lab, you will be assigned into groups of 2 Listen to lab instructions carefully Prepare electrodeposition apparatus (steps 1-3) Move to steps 4-6 Diagnose/Re-test Circuit Step 7
Method Supplies: Copper sulfate and vinegar solution Container Beaker Pencil Lead Graphene filament DC Power supply 2 Alligator clips LEDs Electrical Tape Full assembly & Testing Step 1: Use the multimeter to measure the resistivity of the graphene filament. Write down this value in your lab notebook. Step 2: Put on safety gloves and make the solution. Measure out ~40 grams of copper sulfate using a plastic spoon and a scale. Measure ~236 ml of vinegar with a beaker and combine with the copper sulfate. Stir until the vinegar turns blue and the copper sulfate is dissolved. Step 3: Clamp one end of the first alligator clip to the positive terminal (red) of a DC power source, and clamp the other end to the mechanical pencil lead. Clamp one end of the second alligator clip to the ground terminal (black), and clamp the other end to the graphene filament. BEFORE TURNING ON THE POWER, GET A TA TO CHECK YOU OFF. Step 4: Without letting the alligator clip touch the liquid, submerge the graphene filament in the bowl. Tape the clip to the edge of the bowl. Without letting the alligator clip touch the liquid, submerge the pencil lead in the solution. Tape its alligator clip to the bowl. Step 5: Turn on the power source @ 9V. The copper in the solution will plate onto the graphene filament. (You should see bubbles on the pencil lead.) Step 6: Observe the graphene filament carefully, and record your observations in your lab notebooks. When the graphene filament is completely covered in copper, disconnect the clips from the power source and dry it with a paper towel. Step 7: Measure the resistivity of your electroplated filament with the multimeter. Write this value in your lab notebook. Then test the filament using two electroplated pieces. Connect one piece of filament to the power source s positive terminal with an alligator clip, and the other one to the negative terminal with a second clip. Touch one leg of the LED to each filament, and watch it light up!
Lab notebooks: At the end of this lab you must have all your procedures and observations written down in your lab notebooks. Make sure you record all your observations for full credit. In order to receive full credit, have the TAs check off your lab notebooks. Report: 1. Introduction: 1-2 paragraphs what is electroplating and how does it work? What is your hypothesis or otherwise the aim of this project? 2. Experiment/Design: a. Describe the experimental set-up. Be brief, but I should be able to recreate the experiment with your description. b. With the given materials, how did electroplating actually work? How did the copper deposit onto the filament? c. What are the different physical phenomena you observed during the experiment? What does it mean? d. Why is the relation of current with electroplating? 3. Results: a. Refer to your description in the Experiment/Design section of your report. You will now need to start presenting your measurements and results. b. What were the differences in resistances, before and after the electroplating? Why this change in values? c. Results are quantitative measures we use to prove our theories. What theories have you proven here? 4. Conclusions: a. 1-2 paragraphs. A conclusion is really a restatement of your original hypothesis or aim and a review of whether you supported your hypothesis or achieved your aim. You should reference your results to say why or why not you did or did not achieve your goals, but keep this section short.