Mrs. Henretta
Lab Report
10/6/14
719
Isolating Copper by Electrolysis
I. Abstract
The purpose of this lab is to use electrical energy to isolate copper metal during a chemical
reaction. Paper clips hooked up to a six volt battery acted as electrodes to chemically react copper
chloride solution into copper and chlorine. This activity is relevant to our class discussions on chemical
changes and the law of conservation of mass. Electrolysis is used in many everyday items such as nickel
on the five-cent coin, hydrogen from water for fuel in hydrogen powered cars, and the gold plating that
covers computer chips in electronic devices.
II. Hypothesis
I predict that the color of the copper chloride solution will change from blue to copper color.
III. Materials







250 mL beaker
2 paperclips
six-volt battery
index card
2 alligator clip wires
100 mL of copper chloride solution (CuCl2)
goggles
IV. Diagram
Positive
alligator clip
and wire
Index card
Negative
alligator clip
and wire
Positive paperclip
Negative paperclip
+
+
Battery
Beaker of CuCl2 solution
V. Procedure
1. Gather all the materials needed.
2. Unbend both paperclips to make a hook shape.
3. Push the unbent end of each paperclip through the index card so that they are about three
centimeters apart.
4. Pour 100 mL of the CuCl2 solution into the beaker.
5. Rest the index card on top of the beaker so that the paperclips about halfway submerged in the
solution.
6. Attach one end of an alligator clip wire to one pole of the battery and the other end to one of the
paperclips.
7. Repeat step 6 with the other alligator clip wire onto the other battery pole and paperclip. Do not
let the paperclips touch each other.
8. Observe for 2-3 minutes. Record any observations.
9. Disconnect the paperclips from the wires and remove the index card and paperclips from the top
of the beaker.
10. Observe any changes that may have occurred to the paperclips.
11. Waft the air from the beaker and record any smells.
12. Carefully clean up all materials.
VI. Data and Measurements
Table 1: Before and After Observations
CuCl2 solution
Before
Blue color, 100 mL
After
More Greenish
Positive Paperclip
Silver
Small bubbles
attached, slightly
pointed end
Negative paperclip
Silver
Copper colored,
powdery substance;
pointed end
VII. Observations
Before the experiment, the paperclips were silver colored and had a cylindrical shape. Small
bubbles began to appear on the positive paperclip during the experiment. A copper colored powder
began to form on the negative paperclip. After the experiment, both paperclips were pointed but the
negative paperclip was pointed more. The copper chloride solution changed from a blue color to a more
greenish-blue color afterwards. When the experiment was finished, a slight odor of chlorine, like in a
pool, was detected.
VIII. Conclusion
1. Based on my observations, I believe that solid copper was isolated on the negative paperclip and
gaseous chlorine was isolated on the positive paperclip.
2. Before the electrolysis, the copper and chlorine were chemically combined into CuCl2. This
substance was a bluish liquid. After the chemical reaction, the copper was a brownish solid and
the chlorine was a clear gas.
3. I believe that a chemical reaction did take place because the new substances with new properties
were formed.
4. This reaction does comply with the law of conservation of mass because no new atoms were
created and none were destroyed. The copper and chlorine atoms that used to be combined into a
CuCl2 molecule were separated into Cu and Cl.
5. I predict that if the positive and negative alligator clip wires were switched, then solid copper and
chlorine gas would form on the opposite paperclips.
6. If I had to do this experiment again, I would use nails instead of paperclips because they are
thicker and are made of a different metal. I would also try a more concentrated CuCl2 solution to
see if more copper and chlorine gas would form.