AP CHEMISTRY
Test Booklet
4.9 Redox reactions
1.
The half-reactions for the oxidation-reduction reaction between
and
are represented above. Based
on the half-reactions, what is the coefficient for
if the equation for the oxidation-reduction reaction is
balanced with the smallest whole-number coefficients?
(A) 1
(B)
2
(C)
3
(D) 4
2.
Which of the following is the balanced net ionic equation for an oxidation-reduction reaction between
and
based on the half-reactions represented above?
(A)
(B)
(C)
(D)
AP Chemistry
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Test Booklet
4.9 Redox reactions
3.
A student is given a standard galvanic cell, represented above, that has a Cu electrode and a Sn electrode. As
current flows through the cell, the student determines that the Cu electrode increases in mass and the Sn electrode
decreases in mass.
a. Identify the electrode at which oxidation is occurring. Explain your reasoning based on the student’s
observations.
b. As the mass of the Sn electrode decreases, where does the mass go?
c. In the expanded view of the center portion of the salt bridge shown in the diagram below, draw and label
a particle view of what occurs in the salt bridge as the cell begins to operate. Omit solvent molecules and
use arrows to show the movement of particles.
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AP Chemistry
Test Booklet
4.9 Redox reactions
d. A nonstandard cell is made by replacing the 1.0 M solutions of Cu(NO3)2 and Sn(NO3)2 in the standard
cell with 0.50 M solutions of Cu(NO3)2 and Sn(NO3)2. The volumes of solutions in the nonstandard cell
are identical to those in the standard cell. Cu(NO3)2 and Sn(NO3)2 in the standard cell with 0.50 M
solutions of Cu(NO3)2 and Sn(NO3)2. The volumes of solutions in the nonstandard cell are identical to
those in the standard cell.
i. Is the cell potential of the nonstandard cell greater than, less than, or equal to the cell potential
of the standard cell? Justify your answer.
ii. Both the standard and nonstandard cells can be used to power an electronic device. Would the
nonstandard cell power the device for the same time, a longer time, or a shorter time as
compared with the standard cell? Justify your answer.
e. In another experiment, the student places a new Sn electrode into a fresh solution of 1.0 M Cu(NO3)2 .
i. Using information from the table above, write a net-ionic equation for the reaction between the
Sn electrode and the Cu(NO3)2 solution that would be thermodynamically favorable. Justify that
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Test Booklet
4.9 Redox reactions
the reaction is thermodynamically favorable.
ii. Calculate the value of ΔG° for the reaction. Include units with your answer.
Please respond on separate paper, following directions from your teacher.
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AP Chemistry
Test Booklet
4.9 Redox reactions
4.
A student is given a standard galvanic cell, represented above, that has a Cu electrode and a Sn electrode. As
current flows through the cell, the student determines that the Cu electrode increases in mass and the Sn electrode
decreases in mass.
a. Identify the electrode at which oxidation is occurring. Explain your reasoning based on the student’s
observations.
b. As the mass of the Sn electrode decreases, where does the mass go?
c. In the expanded view of the center portion of the salt bridge shown in the diagram below, draw and label
a particle view of what occurs in the salt bridge as the cell begins to operate. Omit solvent molecules and
use arrows to show the movement of particles.
AP Chemistry
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Test Booklet
4.9 Redox reactions
d. A nonstandard cell is made by replacing the 1.0 M solutions of Cu(NO3)2 and Sn(NO3)2 in the standard
cell with 0.50 M solutions of Cu(NO3)2 and Sn(NO3)2 . The volumes of solutions in the nonstandard cell
are identical to those in the standard cell.
i. Is the cell potential of the nonstandard cell greater than, less than, or equal to the cell potential
of the standard cell? Justify your answer.
ii. Both the standard and nonstandard cells can be used to power an electronic device. Would the
nonstandard cell power the device for the same time, a longer time, or a shorter time as
compared with the standard cell? Justify your answer.
e. In another experiment, the student places a new Sn electrode into a fresh solution of 1.0 M Cu(NO3)2 .
i. Using information from the table above, write a net-ionic equation for the reaction between the
Sn electrode and the Cu(NO3)2 solution that would be thermodynamically favorable. Justify that
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AP Chemistry
Test Booklet
4.9 Redox reactions
the reaction is thermodynamically favorable.
ii. Calculate the value of ∆G° for the reaction. Include units with your answer.
Please respond on separate paper, following directions from your teacher.
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Test Booklet
4.9 Redox reactions
5.
For parts of the free-response question that require calculations, clearly show the method used and the steps
involved in arriving at your answers. You must show your work to receive credit for your answer. Examples and
equations may be included in your answers where appropriate.
Answer the following questions related to the standard galvanic cell represented in the diagram above. The
and
are given in the table below.
reduction half-reactions for
Half-Reaction
0.34
(a) Write the net-ionic equation for the overall reaction that takes place as the cell operates.
Please respond on separate paper, following directions from your teacher.
(b) Calculate the value of
for the cell.
Please respond on separate paper, following directions from your teacher.
(c) Calculate
, in
, for the cell.
Please respond on separate paper, following directions from your teacher.
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AP Chemistry
Test Booklet
4.9 Redox reactions
(d) The following diagram on the left represents the copper nitrate solution in the half‑cell before the galvanic cell
starts to operate. In the following diagram on the right, draw a representation of the solution in the same half‑cell
after the galvanic cell has been operating for some time and is still producing a voltage.
Please respond on separate paper, following directions from your teacher.
(e) Assume that the mass of the
electrode changes by grams in a certain period of time. Write a
mathematical expression for the change in mass of the
electrode during the same period of time.
Please respond on separate paper, following directions from your teacher.
half-cell was made with
of
and the
half-cell
(f) For the standard cell, the
was made with
of
. The experiment was repeated, but this time the
half-cell was
of
and the
half-cell was made with
of
. Is
made with
the cell potential for the nonstandard cell greater than, less than, or equal to the value calculated in part
?
Justify your answer.
Please respond on separate paper, following directions from your teacher.
(g) If the experiment is repeated with the
electrode replaced with a
electrode with twice the mass, will the
initial cell voltage be greater than, less than, or equal to the initial cell voltage in the original experiment? Justify
your answer.
Please respond on separate paper, following directions from your teacher.
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4.9 Redox reactions
6.
The reaction between solid copper and aqueous silver nitrate produces solid silver and a blue solution, as
represented by the balanced equation shown above. Based on the balanced equation, which of the following
identifies the oxidation and reduction half-reactions?
Oxidation Half-reaction
Reduction Half-reaction
Oxidation Half-reaction
Reduction Half-reaction
Oxidation Half-reaction
Reduction Half-reaction
Oxidation Half-reaction
Reduction Half-reaction
(A)
(B)
(C)
(D)
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AP Chemistry