SCH4U Practice Culminating Task for DAY 1: Initiating and Planning
Unit 3: Electrochemistry
A Purpose: To determine the cell potential for the following reaction:
Zn(s) | Zn2+(aq) || Cu2+(aq) | Cu(s)
Pre-Lab Question:
Consider the following shorthand representation of an electrochemical cell.
Al(s) | Al3+(aq) || Ni2+(aq) | Ni(s)
a) Sketch the electrochemical cell. Mark the anode, the cathode, the salt bridge, and the charge
of each electrode. Indicate the direction of electron and ion movement.
e-
>
K
>
salt bridge
anode
anions
Al
Al3+
cathode
cations
Ni
Ni2+
LEO
GER
b) Write the half-reactions that occur at the anode and the cathode.
K
Anode:
Al(s)  Al3+ + 3e-
Cathode
Ni2+ + 2e-  Ni(s)
c) Calculate the cell potential.
K
Ecell = + 1.662 V – 0.257 V
= + 1.405 V
d) Explain two different ways to produce Al (s) at the cathode instead of Ni (s)


attach a battery to force the electrons to flow in the opposite direction
use a metal electrode and electrolyte that has a lower reduction potential than Al
A Materials and Equipment:
Salt bridge
Copper electrode
Zinc electrode
CuSO4
Zn(NO3)2
3.0 M KNO3
cotton balls
black and red alligator clips
water
graduated cylinder
electronic balance
scoopula
2 beakers (250 mL)
2 beakers (500 mL)
100 mL beaker
voltmeter
C Safety Precautions
Wear safety goggles and gloves
Handle the nitric acid solution with care. It is an irritant. Wash any spills on your skin with
copious amounts of water, and inform your teacher.
C Procedure
1. In a 250 mL beaker, prepare the Zn(NO3)2 electrolyte solution by adding 37.88 g of solid
Zn(NO3)2 to 200 mL of water.
2. In a 250 mL beaker, prepare the CuSO4 electrolyte solution by adding 31.92 g of solid
CuSO4 to 200 mL of water.
3. Prepare the 60 mL 0.5 M KNO3 salt bridge solution by diluting the given 3.0M KNO3.
A
C1V1 = C2V2
Take 10 mL of the 3.0 M solution and add 50 mL of water, using a
graduated cylinder..
4. Fill the salt bridge with the 0.5 mol/L KNO3 electrolyte solution. Insert a cotton plug into both
ends.
5. Insert each metal electrode into the corresponding beaker.
6. Attach the alligator clip on the red to the red probe of voltmeter. Attach the black lead to the
black probe.
7. Insert one end of the salt bridge into the solution in the first beaker. Insert the other end of
the salt bridge into the solution in the second beaker. Attach a free alligator clip to the
electrode in each well.
8. Record the reading on the voltmeter.
9. Disassemble the galvanic cell and dispose of the solutions in the waste container.
C Observations
Draw a labeled galvanic cell. Be sure to include:
 the anode and the cathode
 salt bridge
 electrolyte solutions
 write a balanced equation for the half-reaction, the oxidization half-reaction, and the
overall cell reaction.
 the direction in which the electrons flow through the external circuit
 the movements of ions in the cell
 the cell potential