Chemistry
Electroplating
2013-14
Name:___________________________________
MODs:_____________Date:_________________
Lab Partner(s):____________________________
BACKGROUND: Electroplating is an
economically important process, often used to
reduce corrosion or improve the appearance of
objects.
During electroplating, the object to be plated is
attached to the negative post of a power source,
causing the object to gain a negative charge. This
will attract positive metallic cations from the
electrolytic solution, or “bath,” the object is placed in. In this experiment, positive Cu 2+
ions from the bath will become attracted to a nail carrying the negative charge. When
the Cu2+ reach the nail they will gain electrons and become form solid copper:
Cu2+ (aq) + 2e-  Cu(s)
The copper (II) ions removed from the bath must be replenished; this is accomplished at
the anode where a solid copper plate undergoes oxidation:
Cu(s)  Cu2+ (aq) + 2eObjective: To use electroplating to plate copper onto a metal object such as a nail.
Pre-Lab Questions: (You may use a separate sheet of paper for responses)
1. Define the following terms: (Use scientific definitions)
ELECTROLYSIS:
CATHODE:
ANODE:
CURRENT:
AMPERE:
2. Describe the flow of electrons during the electroplating process. (Diagrams are
acceptable)
Equipment and Materials:
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Cathode – an iron nail (or small object from home like a coin)
Anode – A copper strip (approx. 5 cm x 1 cm)
Electrolytic solution – 1.0 M CuSO4
9V battery
250 ml beaker
Insulated wire leads with alligator clips at both ends and a battery attachment
Uninsulated copper wire
Steel wool
Wood stirrer (used to suspend the item to be plated)
timer
Balance and weigh boats
Safety: Copper sulfate is slightly toxic by ingestion. Do not operate electrical circuits
with wet hands or in wet areas. BE SURE the area is dry prior to completing a circuit.
Wear chemical splash goggles. Wash hands thoroughly with soap and water before
leaving the classroom. Follow all laboratory safety guidelines. SDS are available upon
request.
Procedures:
1. Clean the nail (or object to be plated) and the copper strip by polishing it with steel
wool.
2. Obtain the mass of the object being plated and record it on the data sheet.
3. Use the uninsulated copper wire to suspend the item to be plated (nail, etc) into the
empty beaker. Attach one end of the BLACK alligator chip to the copper wire
supporting the nail and the other end to the NEGATIVE post (cathode) of the battery or
power source.
4. Place the copper strip, the anode, into the empty beaker. Attach one end of the RED
alligator clip to the copper strip and attach the other end, to the POSTIVE post of the
battery or power source.
5. Carefully pour the CuSO4 solution into the beaker until it is about two-thirds full.
Make sure the entire nail is submerged.
6. Allow the reaction to continue for 10 minutes or so. Record you observations while
electroplating is continuing. Record the total time used for the plating process.
7. Obtain the mass of the plated object and record it on the data sheet.
Data Sheet:
1. Mass of the object prior to plating:____________________________________
2. Record your observations during the plating process: (drawings may help)
3. Mass of the object after plating:______________________________________
4. Calculate the change in mass of the object:____________________________
5. Time of the reaction (minutes):_______________________________________
Post Lab Questions: (Use a separate sheet of paper for responses)
1. What is causing the change in mass in the object?
2. Write the half-reaction that occurs at the ANODE of the electrolytic cell. Is it
oxidation or reduction?
3. Write the half-reaction that occurs at the CATHODE of the electrolytic cell. Is it
oxidation or reduction?
4. Calculate the current (in amperes) that as flowing through the electrolytic cell.
(Use the mass of the copper placed and the time that it took to plate the object to
find the value.)