ChemQuest 83
Name: ____________________________
Date: _______________
Hour: _____
Information: Galvanic Cell Diagram
The direction of electron
movement follows either
the solid arrow or the
dashed arrows. Only one
path is correct and you
will find out which one
as you go through the
Critical Thinking
Questions.
A galvanic cell is made of two
electrodes. In this Galvanic cell you
should see a copper and a zinc
electrode.
By not allowing the copper and zinc to
directly touch each other, the Galvanic
cell forces electrons to travel through a
wire. The voltage in the wire can be
measured using a voltmeter. By using
a table of standard electrode reduction
potentials, the cell voltage can be
calculated.
Electrons leave one electrode and
travel to the other electrode. In the
questions that follow you will find out
which direction the electrons follow.
Cu+2 + 2e-  Cu
cathode
Zn  Zn+2 + 2eanode
Critical Thinking Questions
1. Given the above diagram of the copper-zinc Galvanic cell, at which electrode does
oxidation occur—the copper or zinc electrode?
Zinc electrode
2. At one of the electrodes, electrons are produced and at the other electrode electrons are
absorbed. Look at the equations below each electrode in the diagram to determine what
happens at each electrode.
zinc
Electrons are produced at the ____________
electrode and absorbed at the
copper OR zinc
____________ electrode.
copper
copper OR zinc
3. Given your answer to the previous question, you can determine which direction electrons
flow through the wire in the Galvanic cell. Which direction in the above diagram is
correct—the solid arrows or the dashed arrows? (Cross out the wrong arrows.)
4. The oxidation electrode is called the “anode” and the reduction electrode is called the
“cathode.” In the diagram above there are two blanks that you can use to label the anode
and the cathode.
5. Use a table of standard Eo values to calculate the voltage of the copper-zinc cell.
0.34 + 0.76 = 1.1 V
6. Write the overall reaction for the copper-zinc cell. Recall that you get an overall reaction
by adding the two half reactions together.
Cu+2 + Zn  Cu + Zn+2
7. Draw a picture of a Galvanic cell similar to the picture in the information section. The
overall reaction that occurs is: Cr+3 + Al  Cr + Al+3
Include the following in your picture:
a) The anode in a beaker on the right, cathode on the left. Label each.
b) Instead of a sulfate solution, use a nitrate solution.
c) Indicate the direction of electron flow.
d) Calculate the overall cell potential using a table of standard Eo values.
Direction of electron flow
Ecell = -0.74 + 1.66 = 0.92 V
Cr(NO3)3 (aq)
Cr
3e- + Cr+3  Cr
cathode
Al
Al(NO3)3 (aq)
Al  Al+3 + 3eanode
Information: Spontaneous or Non-spontaneous?
In questions 5 and 7 above you calculated the cell potential using standard Eo values. You
should have found that both values were positive numbers. For an electrochemical reaction to be
spontaneous it must have a positive overall cell potential (Ecell).
Critical Thinking Questions
8. Determine whether the following are spontaneous or non-spontaneous based on
calculated Ecell values.
a) Mg+2 + Mn  Mg + Mn+2
b) Pb+2 + Cd  Pb + Cd+2
nonspontaneous
spontaneous
-2.37 + 1.18  negative Ecell
-0.13 + 0.40  positive Ecell
9. Would the following electrochemical cell be spontaneous?
Anode: Sn  Sn+2 + 2eCathode: Fe+2 + 2e-  Fe
E = +0.14
E = -0.41
The cell is not spontaneous because the Ecell would be positive.
anode
10. In a spontaneous cell, electrons always flow from the _____________
to the
_____________.
anode OR cathode
cathode
cathode
anode OR