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Electroplating
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In this experiment, you will conduct, observe, and measure the process of electroplating. This
process is used to deposit a layer of metal, such as chromium, copper, or gold, onto another
metal. As a commercial process, electroplated coatings are used to improve appearance, resist
corrosion, or improve hardness of metallic surfaces. This experiment describes one method of
producing a copper coating on a brass key or other suitable metallic object.
You will prepare an electrochemical cell by using a copper strip as the cathode (positive
terminal) and a brass key is as the anode (negative terminal). The electrodes are immersed in a
solution containing acidified copper (II) sulfate. As you apply a potential to the electrodes, you
will be effectively transferring Cu atoms from the anode to the surface of the brass key.
This process is expressed in equation form below.
Mass deposited at an electrode 
I  t  ( MM )
96,500  n
I is the current in amperes; t is the time that the current is applied, in seconds; MM is the molar
mass of the element that is deposited; n is the number of moles of electrons/mol; and 96,500 is ₣,
the Faraday constant.
Figure 1
OBJECTIVES
In this experiment, you will



Prepare and operate an electrochemical cell to plate copper onto a brass surface.
Measure the amount of copper that was deposited in the electroplating process.
Calculate the amount of energy used to complete the electroplating process.
Advanced Chemistry with Vernier
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MATERIALS
LabPro or CBL 2 interface
TI graphing calculator
Vernier Current Probe
1.5 volt DC power supply
four connecting wires with alligator clips
steel wool
250 mL beaker
distilled water
electrolyte solution (CuSO4 in H2SO4)
vinegar
1 cm × 10 cm copper strip
brass key
solid sodium chloride, NaCl
250 mL beaker
analytical balance
bare copper wire, 20-22 gauge
PROCEDURE
1. Obtain and wear goggles.
2. Use steel wool to clean a brass key and a strip of copper, which will be the electrodes of the
electrochemical cell.
3. Mix 3 g of NaCl with 15 mL of vinegar in a 250 mL beaker. Wash the key and the copper
strip in this salt/vinegar solution. Rinse the key and copper strip with distilled water and dry
each metal piece.
4. Use an analytical balance to measure the mass of the key and the copper strip. Record the
masses in your data table.
5. Fill a 250 mL beaker about ¾ full with the electrolyte solution. CAUTION: The electrolyte
solution in this experiment is prepared in H2SO4 and should be handled with care.
6. Attach a 7 cm length of bare copper wire to the brass key to act as a handle. Connect the wire
to the alligator clip for the anode, so that the key will be completely immersed in the
electrolyte solution but the alligator clip will not be immersed. Connect the copper strip to
the positive lead. Important: You will not place the electrodes in the beaker until Step 11.
7. Obtain a DC power supply and a Vernier Current Probe. Use connecting wires, with alligator
clips, to connect the DC power supply, Current Probe, and the electrodes. See Figure 1 for
the proper setup of the wiring. Important: You will not place the electrodes in the beaker
until Step 11.
8. Plug the Current Probe into Channel 1 of the LabPro or CBL 2 interface. Use the link cable
to connect the interface to the TI graphing calculator.
9. Set up the calculator and interface for the Current Probe.
a. Turn on the calculator and start the DATAMATE program. Press CLEAR to reset the program.
b. Select SETUP from the Main screen. If CH 1 displays CURRENT (AMP) proceed directly to
Step 10. If it does not, continue with this step to set up the sensor manually.
c. Press ENTER to select CH 1.
d. Select CV SYSTEM and CV CURRENT (A) from the sensor list, after selecting MORE a few
times.
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Electroplating
10. Set up the data collection mode.
a. To select MODE, press
until the cursor is to the left of MODE and press ENTER .
b. Select TIME GRAPH from the SELECT MODE menu.
c. Select CHANGE TIME SETTINGS. Type “30”, for the time between samples in seconds, then
press ENTER . Type “60”, for the number of samples, then press ENTER . Data will be
collected for 30 minutes.
d. Select OK twice to return to the Main screen.
11. Place the key and the copper strip into the electrolyte solution in the beaker. Make sure that
the key is completely immersed in the solution, and keep the two electrodes as far apart as
possible.
12. Turn on the DC power source and check the sensor readings. The initial current should be in
the 0.2-0.6 amp range. If the current is not in this range, check with your instructor before
proceeding.
13. Begin data collection. Observe the electrolysis. Note the slow deposition of copper on the
surface of the key. The data collection will run for 30 minutes.
14. When the data collection is complete, turn off the DC power source and carefully remove the
copper strip and key from the electrolyte solution. Rinse the two metals with distilled water.
Dry the copper strip and key very carefully, so as not to remove copper.
15. Determine the average current applied during the experiment.
a.
b.
c.
d.
e.
f.
g.
Press ENTER to return to the Main screen.
Select ANALYZE from the Main screen.
Select STATISTICS from the ANALYZE OPTIONS screen.
Press ENTER to choose the first data point as the left bound.
Use the
key to move the cursor to the last data point on the graph, and press ENTER .
Record the mean in your data table as the average current.
Press ENTER to return to the ANALYZE OPTIONS screen, and then select RETURN TO MAIN
SCREEN. Select QUIT to exit the DATAMATE program.
16. Measure and record the mass of the dry copper strip and key.
17. Discard the electrolyte solution and take care of the electrochemical cell as directed.
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DATA TABLE
Initial mass of copper electrode (g)
Final mass of copper electrode (g)
Initial mass of key (g)
Final mass of key (g)
Average current (A)
Time of current application (s)
DATA ANALYSIS
1. Calculate the number of coulombs of charge passed through the electrolytic cell.
2. Calculate the theoretical number of moles of copper that should have plated out onto the
brass key.
3. Calculate the actual number of moles of copper that plated out.
4. Calculate the percent yield of copper.
5. Suggest the sources of error in your experiment.
6. Write the oxidation and reduction half-reactions for this process.
7. Must the surface to be electroplated be a metal? Explain.
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Advanced Chemistry with Vernier