Department of Chemistry
University of Texas at Austin
Name:____________________
Electrochemical Cells – Supplementary Worksheet KEY
Experimental Observations of Electrochemical Cells
1. Consider the voltaic cell that contains standard Co2+/Co and Au3+/Au electrodes. The
following experimental observations were noted: (1) Metallic gold plates out on one
electrode and the gold ion concentration decreases around that electrode, and (2)
The mass of the cobalt electrode decreases and the cobalt (II) ion concentration
increases around that electrode.
a. Diagram this voltaic cell. Make sure to
i. Indicate the anode, cathode, positive and negative electrodes
ii. Write out the ½ reactions and their type occurring at each electrode
iii. Write out the overall balanced redox reaction that goes with this cell
iv. Label the direction of electron flow and the current
v. Label the direction of anions and cations in the salt bridge
See figure for answers to i. through v.
b. Diagram the cell using the short hand notation
<Co(s)|Co2+(aq)||Au3+(aq)|Au(s)>
c. What is the standard cell potential of this voltaic cell?
E°cell = E°cathode - E°anode = 1.50 V – (-0.28 V) = 1.78 V
Revised CR 1/16/14
© LaBrake & Vanden Bout 2014
Department of Chemistry
University of Texas at Austin
Name:____________________
2. Consider the electrolysis of molten calcium chloride with inert electrodes. The
following experimental observations were noted: (1) Bubbles of pale green chlorine
gas are produced at one electrode, and (2) Silvery white molten metallic calcium is
produced at the other electrode.
a. Diagram this electrolytic cell. Make sure to
i. Indicate the anode, cathode, positive and negative electrodes
ii. Write out the ½ reactions and their type occurring at each electrode
iii. Write out the overall balanced redox reaction that goes with this cell
iv. Label the direction of electron flow and the current
v. Label the direction of anions and cations in the salt bridge
See figure for answers to i. through v.
b. Diagram the cell using the short hand notation
<Pt(s)|Cl-(aq)|Cl2(g)||Ca2+(aq)|Ca(s)|Pt(s)>, you can use any kind of inert
electrodes, here we used platinum
c. What is the standard cell potential of this electrolytic cell?
E°cell = E°cathode - E°anode = -2.76 V – (1.36 V) = -4.12 V
Revised CR 1/16/14
© LaBrake & Vanden Bout 2014
Department of Chemistry
University of Texas at Austin
Name:____________________
3. Problem 1 is an example of a galvanic or voltaic cell. Problem 2 is an example of an
electrolytic cell. Considering the diagrams of these two cells, what are the
differences and similarities between galvanic (voltaic) cells and electrolytic cells?
Differences between the galvanic and electrolytic cells are the galvanic cell has a
positive standard cell potential while the electrolytic cell has a negative one, the
signs of the cathode and anode are reversed, and there is a battery in the electrolytic
cell and not in the galvanic cell.
Similarities are oxidation happens at the anode and reduction happens at the
cathode in both, anions go towards the anode and cations go towards the cathode in
both, electrons flow towards the cathode and the current goes towards the anode in
both, and the standard cell potential is calculated using the same equation.
Revised CR 1/16/14
© LaBrake & Vanden Bout 2014
Department of Chemistry
University of Texas at Austin
Name:____________________
Short Hand Notation of Electrochemical Cells
4. Consider the following cell <Ni(s)|Ni2+(aq)||Ag+(aq)|Ag(s)>
a. Diagram this cell. Make sure to
i. Indicate the anode, cathode, positive and negative electrodes
ii. Write out the ½ reactions and their type occurring at each electrode
iii. Write out the overall balanced redox reaction that goes with this cell
iv. Label the direction of electron flow and the current
v. Label the direction of anions and cations in the salt bridge
See figure for answers to i. through v.
b. What is the standard cell potential of this cell?
E°cell = E°cathode - E°anode = 0.80 V – (-0.23 V) = 1.03 V
c. Is this cell a galvanic cell or an electrolytic cell?
Galvanic, because E°cell is positive
Revised CR 1/16/14
© LaBrake & Vanden Bout 2014
Department of Chemistry
University of Texas at Austin
Name:____________________
5. Consider the following cell
<Pt(s)| Ce3+(aq)|Ce4+(aq)||Cu2+(aq) |Cu(s)>
a. Diagram this cell. Make sure to
i. Indicate the anode, cathode, positive and negative electrodes
ii. Write out the ½ reactions and their type occurring at each electrode
iii. Write out the overall balanced redox reaction that goes with this cell
iv. Label the direction of electron flow and the current
v. Label the direction of anions and cations in the salt bridge
See figure for answers to i. through v.
b. What is the standard cell potential of this cell?
E°cell = E°cathode - E°anode = 0.34 V – (1.70 V) = -1.36 V
c. Is this cell a galvanic cell or an electrolytic cell?
Electrolytic, because E°cell is negative
Revised CR 1/16/14
© LaBrake & Vanden Bout 2014
Department of Chemistry
University of Texas at Austin
Name:____________________
Electrochemical Cell Diagrams
6. Consider the following cell:
a. Would you assume this cell is a voltaic or an electrolytic cell? Why do you
think this?
We would assume this cell is an electrolytic cell because it includes a battery
or power source.
b. Knowing this complete the diagram of this cell by
i. Indicating the anode, cathode, positive and negative electrodes
ii. Writing out the ½ reactions and their type occurring at each electrode
iii. Writing out the overall balanced redox reaction that goes with this cell
iv. Labeling the direction of electron flow and the current
v. Labeling the direction of anions and cations in the salt bridge
See figure for answers to i. through v.
Revised CR 1/16/14
© LaBrake & Vanden Bout 2014
Department of Chemistry
University of Texas at Austin
Name:____________________
c. What is the short hand notation for this cell?
<Cu(s)|Cu2+(aq)||Zn2+(aq)|Zn(s)>
d. What is the standard cell potential of this cell?
E°cell = E°cathode - E°anode = -0.76 V – (0.34 V) = -1.10 V
Revised CR 1/16/14
© LaBrake & Vanden Bout 2014
Department of Chemistry
University of Texas at Austin
Name:____________________
7. Consider the following cell:
a. Would you assume this cell is a voltaic or an electrolytic cell? Why do you
think this?
We would assume this cell is a galvanic cell because it does not include a
battery or power source and is powering a light bulb.
b. Knowing this complete the diagram of this cell by
i. Indicating the anode, cathode, positive and negative electrodes
ii. Writing out the ½ reactions and their type occurring at each electrode
iii. Writing out the overall balanced redox reaction that goes with this cell
iv. Labeling the direction of electron flow and the current
v. Labeling the direction of anions and cations in the salt bridge
See figure for answers to i. through v.
Revised CR 1/16/14
© LaBrake & Vanden Bout 2014
Department of Chemistry
University of Texas at Austin
Name:____________________
c. What is the short hand notation for this cell?
<Zn(s)|Zn2+(aq)||Cu2+(aq)|Cu(s)>
d. What is the standard cell potential of this cell?
E°cell = E°cathode - E°anode = 0.34 V – (-0.76 V) = 1.10 V
8. The cells in problems 6 and 7 have almost the same components. However, one is
galvanic and one is electrolytic. What are some of the similarities and differences
between these two problems?
Differences between the galvanic and electrolytic cells are the galvanic cell (problem
7) has a positive standard cell potential while the electrolytic cell (problem 6) has a
negative one, the signs of the cathode and anode are reversed, and there is a battery
in the electrolytic cell and not in the galvanic cell.
Similarities are oxidation happens at the anode and reduction happens at the
cathode in both, anions go towards the anode and cations go towards the cathode in
both, electrons flow towards the cathode and the current goes towards the anode in
both, and the standard cell potential is calculated using the same equation.
Revised CR 1/16/14
© LaBrake & Vanden Bout 2014