Chemistry Lab
Lab 10 (Electrolysis of a Salt)
Name ____________________________
Background Information
Electrolysis A method that uses electricity to separate compounds by attracting ions in aqueous solutions to the
opposite electrode. This means the Metal cation will be attracted to the negative electrode and Nonmetal anions
will be attracted to the positive electrode. (Opposite charges attract)
Electrolysis on an industrial scale uses very large quantities of electrical energy, making it an expensive,
although effective, method of obtaining or purifying metals. In the industrial method of copper refining used
today, pure copper is produced by electrometallurgy form less pure copper produced by pyrometallurgy.
In this activity you will produce copper metal and chlorine gas from a solution of copper (II) chloride (CuCl2)
using electrolysis. A 9-V battery will provide the electric current.
A complete Lab Report for this activity should be included in the Lab Section of your class folder.
Procedure
1. Put on your safety goggles and lab apron.
2. Obtain two graphite (carbon) rods in the form of pencil lead. Clean the rods with sandpaper or emery
paper if necessary.
3. Set up the electrolysis apparatus as shown on the back of this lab sheet. Connect the alligator clamps to the
carbon rods, but do not connect them yet to the 9-V battery.
4. If necessary, add copper (II) chloride (CuCl2) solution to the U-tube so that the carbon rods can be one-forth
to one-half immersed in the solution.
5. Have your teacher approve the set up.
6. After your teacher has approved the set up, attach the wires to the 9-V battery.
7. Observe the reaction for approximately five minutes and record your observations in the observation
section of your lab report in your class folder or lab notebook.
8. Cautiously sniff each carbon rod.
Questions
1. Describe the changes that occurred during the experiment.


2.
The carbon rod attached to the (-) terminal of the battery had a red solid build-up on the end.
The carbon rod attached to the (+) terminal of the battery produced bubbles of gas that smelled
like the chlorine in a swimming pool.
One electrode, called the cathode, is the place where reduction takes place.
a. Which ion would have gained electrons (Reduction) to form a neutral element? (GER)
Circle one:
b.
or
Chloride, Cl-
(aq)
Which electrode was the cathode in the experiment?
Circle one:
c.
Copper (II), Cu2+(aq)
(+) Battery Terminal
or
(-) Battery Terminal
What change did you observe at the cathode in this reaction?

There was a red solid building up on the end of the graphite pencil rod.
d. At the cathode, electrons were ____ the ions in the solution?
Circle one:
added to
or
released by
3.
The other electrode, called the anode, is where oxidation takes place. (LEO)
a. Which ion would have electrons removed (Oxidation) to form a neutral element?
Circle one:
b.
or
Chloride, Cl- (aq)
Which electrode was the anode in the experiment?
Circle one:
c.
Copper (II), Cu2+(aq)
(+) Battery Terminal
or
(-) Battery Terminal
What change did you observe at the anode in this reaction?

Tiny bubbles of gas were produced that had a distinct smell like the chlorine in a swimming
pool.
d. What product was formed at the anode? How was this product determined?

e.
Chlorine gas. The gas was probably chlorine gas because it smelled like chlorine.
At the anode, electrons were ____ the ions in the solution?
Circle one:
4.
added to
or
released by
Write a balanced equation for the overall chemical reaction that took place in this electrolysis reaction.
(The oxidation product is gaseous chlorine, Cl2 (g))
electrolysis
CuCl2 (aq)

Cu(s) +
Cl2(g)