U6 Micro-Electrolysis of Copper Chloride
Chemical Concepts




A battery is like an electron pump, and conducting wires are similar to pipes, allowing electrons to
flow from one site to another.
When applied to a chemical reaction, a battery can pump electrons away from a reactant at one
electrode (This reactant, that is losing electrons, is said to be "oxidized"; the electrode, where this
occurs, is known as the "anode.").
The battery can simultaneously pump electrons onto another reactant at the other electrode (This
reactant, that is gaining electrons, is said to be "reduced"; the electrode, where this occurs, is known
as the "cathode.").
A chemical reaction consumes the reactants.
Objective : to determine the charge of products formed when an electric current is passed through a
copper (II) chloride (CuCl2) solution.
Prelab questions: Answer in complete sentences in your lab NB.
1. Contrast the conductivity of the solid CuCl2 and the CuCl2 solution.
2. Based on our discussion of the results of the Conductivity Lab, what does this suggest about this
substance as a solid and in solution?
3. Describe and sketch happens to the CuCl2 particles when they dissolve in water.
Procedure
1. Obtain a micro U-tube filled with copper(II) chloride (CuCl2) solution and a 9-V battery with micro
carbon (graphite) rods. (Be careful, the rods break easily!)
2. Place the U-tube in a small beaker, then place the electrodes in the CuCl2 solution -- one at each end
of the U-tube. Each rod should be about half submerged in the solution. Do not submerge them all
the way up to their connecting wires. Observe the reactions taking place at each electrode (rod).
Also carefully sniff each electrode. Record.
3. Sketch the U-tube apparatus right after you set it up. and after you allow the reactions to run for
approximately 30 minutes. [Make sure your sketch indicates which electrode is positive(+) (connected
to the red wire) and which is negative(-) (connected to the black wire). Record what you observe
happening at each electrode.
4. Label your beaker and place it in the fume hood.
5. Observe and sketch what has occurred after 24 hours.
6. Dismantle and clean the electrolysis apparatus.
Questions: Answer in complete sentences in your lab NB.
1. Describe what you observed forming at the postive electrode. Based on the formula of copper
chloride and the appearance of the substance, what do you think this substance is? Why were
these particles attracted to this electrode?
2. Describe what you observed forming at the negative electrode. Based on the formula of
copper chloride and the appearance of the substance, what do you think it is? Why were these
particles attracted to this electrode?
3. What is the charge of a copper ion? Describe your evidence for this from the lab.
4. What is the charge of a chloride ion? Describe your evidence for this from the lab.
5. Explain the color change of the solution.