BCLN CHEMISTRY 12 - Rev. July/2018
Unit 5 ~ Learning Guide Name: ______________________________
Instructions:
Using a pencil, complete the following notes as you work through the related lessons. Show ALL
work as is explained in the lessons. You are required to have this package completed BEFORE
you write your unit test. Do your best and ask questions if you don’t understand anything!
Please print out the Formula Sheet and found at the start of the course. You will need this
to do assignments and tests!
Electrochemistry:
1. What is the difference between a reduction reaction and an oxidation reaction?
2. What simple phrase involving a majestic animal should help you remember this
difference? Explain how it works!
3. One way to keep agents straight is to think of them as spies who are secret agents for the
other side. Try to explain what is meant by this statement.
4. What is the difference between an electrochemical cell and an electrolytic cell?
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BCLN CHEMISTRY 12 - Rev. July/2018
5. Define oxidation number
6. What is the oxidation number of any element in its standard state?
7. If you see a charge on an individual ion, what will the oxidation number for that ion be?
8. What is the common oxidation number for oxygen?
9. What is the common oxidation number for hydrogen?
10. Determine the oxidation number of each of the following. Note that the same element
can have different oxidation numbers in different compounds.
Species
Au
Work/Explanation
H in H2
Na in Na2S
S in Na2S
S in CaSO4
O in BaO2
P in AlPO4
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Oxidation Number
BCLN CHEMISTRY 12 - Rev. July/2018
11. Put the oxidation of each underlined element below it. Determine if each underlined
element has undergone reduction, oxidation or no change.
Reaction
Oxidation/Reduction/No Change
P4 becomes PO43-
BaO2 becomes BaO
H2S becomes H2SO4
Mn4+ becomes MnO2
H2O becomes KH
The Standard Reduction Table:
1. The oxidizing agents on the left side of the Standard Reduction Potentials of Half Cells
are all undergoing what chemical process?
2. What diagonal shape is drawn on The Standard Reduction Table between two species
which would undergo a spontaneous reaction?
3. What diagonal shape is drawn on The Standard Reduction Table between two species
which would NOT undergo a spontaneous reaction?
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BCLN CHEMISTRY 12 - Rev. July/2018
4. Answer yes or no to each of the following. Be careful with the "is it safe to store"
questions!
Situation
Yes/No
Will neutral water oxidize strontium metal?
Is it safe to store copper metal in water?
If fluorine gas is bubbled into water, is there a reaction?
Could an mercury (II) nitrate solution be stored in a silver container?
Is it safe to have lithium solid anywhere near fluorine gas?
Will hydrochloric acid (H+ and Cl-) react with Tin Metal?
Will hydrochloric acid (H+ and Cl-) react with Manganese (IV) oxide?
5. Give the symbol for a cation that will oxidize calcium but not magnesium.
6. If you place Fe3+ ions in a basic solution a reaction will occur but you will not see any solid iron
metal forming. Explain why this is so.
7. In the past when balancing reactions you only had to worry about making sure each type of atom
was balanced. Now you have two new things to balance. One of those is overall charge. In other
words if you have an overall +2 charge in your reactants you must also have an overall charge of
+2 in your products. What is the final thing you must ensure is balanced when creating correct
redox reactions?
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BCLN CHEMISTRY 12 - Rev. July/2018
8. Write a balanced net ionic equation for the redox reaction that occurs given each of the following
sets of reactants. Be careful to identify spectator ions and not include them in your calculations.
a) Cl2(g) and Ni(s)
b) Br2(g) and Al(s)
c) Acidified KMnO4 and KI
d) Au(NO3)3 and neutral water. You should not have fractional coefficients in your final answer!
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BCLN CHEMISTRY 12 - Rev. July/2018
9. The four metals, Strontium(Sr), Francium (Fr), Yttrium (Y), and Europium (Eu), in separate
experiments, are dipped in aqueous solutions of SrNO3, FrNO3, Y(NO3)3, and Eu(NO3)2. The
following results are obtained:
1. Yttrium metal does not react with any of the solutions
2. Strontium metal reacts with all of the other metals solutions
3. Francium metal reacts in a solution of Eu(NO3)2
a) List the four oxidizing agents in order from strongest to weakest by creating a small reduction table.
Explain your reasoning below!
Oxidizing Agents
Reducing Agents
b) List the four reducing agents in order from strongest to weakest
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BCLN CHEMISTRY 12 - Rev. July/2018
Balancing Reactions:
1. What are the names of the two methods used to balance redox reactions?
2. Balance the following using the oxidation number method. Start by writing the oxidation number
of each atom in each compound beneath it. Explain your steps in the space below
Cr2O72-
+
S(s)
 Cr3+ + SO32-
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...in acid
BCLN CHEMISTRY 12 - Rev. July/2018
3. Balance the following using the oxidation number method. Start by writing the oxidation number
of each atom in each compound beneath it
MnO2 +
BrO3-
 MnO4- + Br2(l)
...in base
4. Balance the following using the half reaction method.
NO3-
+
Hg(l)
 Hg2+ + NO(g)
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...in acid
BCLN CHEMISTRY 12 - Rev. July/2018
5. Balance the following using the half reaction method.
PO33-
ClO4-
+
 PO43-
+ Cl-
...in base
6. Balance the following using the half reaction method.
AuCl4-
+
H2
 Au(s)
+ 4 Cl-
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+
2H+
...in base
BCLN CHEMISTRY 12 - Rev. July/2018
The Electrochemical Cell:
1. What does ULIRBLRWIO stand for?
2. Will you ever double or triple an Eo value? Explain.
3. What cell was used to measure the Eo values of all other cells? What is the Eo value for this cell?
4. If a reduction half reaction had Eo = -4.52, what would be the E0 value of the same reaction in
reverse (oxidation)?
5. Determine if the reaction below is spontaneous by calculating the net Eo.
3 Hg(l)
+
2 NO3- + 8 H+  3 Hg2+ + 2 NO(g)
+ 4 H2O
6. What would the net Eo be for the reverse reaction of the one shown in question 5. Would it be
spontaneous?
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BCLN CHEMISTRY 12 - Rev. July/2018
7. What process (oxidation or reduction) occurs at the anode in an electrochemical cell?
8. What is the purpose of the salt bridge in an electrochemical cell?
9. Will Hg2+ ions react with water to produce Hg metal? Explain. Be careful, the overpotential
effect comes into play here!
10. What are two common terms for the oxidation of a metal?
11. What are the only two metals that can be used to cathodically protect Rubidium? Bonus: Why
is this unlikely to work very well?
12. A very expensive electrochemical cell is set up with a silver electrode in a solution of silver
nitrate in the first beaker and a gold electrode in a solution of gold nitrate in the second beaker.
The electrodes are connected with a wire and a salt bridge is used to connect the two beakers.
a) Write the two half reactions with their correct Eo. Indicate which is undergoing reduction
and which is undergoing oxidation. Determine the net reaction and the net Eo.
b) Identify the cathode and the anode in this cell.
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BCLN CHEMISTRY 12 - Rev. July/2018
c) Identify the species reduced and the species oxidized.
d) In this cell (as in all electrochemical cells) electrons move from the :
_______________ to the ____ __________
13. Consider the electrochemical cell shown below?
a) Write the two half reactions with their correct Eo. Indicate which is undergoing reduction
and which is undergoing oxidation. Determine the net reaction and the net Eo.
b) As the reaction proceeds which ion will decrease in concentration and which will increase?
c) Which electrode will increase in mass as the reaction proceeds, the cathode or the anode?
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BCLN CHEMISTRY 12 - Rev. July/2018
Electrolytic Cells:
1. What are the two most common materials used to make inert electrodes?
2. Platinum electrodes are used in a molten solution of AlI3 in an electrolytic cell. Write the two
half reactions that occur with their correct Eo. Indicate which is undergoing reduction and which
is undergoing oxidation. Determine the net reaction and the net Eo.
3. What is the complication added when comparing a type II electrolytic cell to a type I electrolytic
cell?
4. How do you determine which species will be reduced in an electrolytic cell?
5. How do you determine which species will be oxidized in an electrolytic cell?
6. Direct current is passed through inert electrodes in a 1.00 M solution of CuF. Identify which
species will be oxidized and reduced and then write the two half reactions and the net reaction for
the events which occur. Also calculate the net E° value.
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BCLN CHEMISTRY 12 - Rev. July/2018
7. For a Tin ion | Tin || Silver | Silver ion cell ( this could be abbreviated as Sn2+ | Sn || Ag| Ag+ )
a) Write two half reactions and the net reaction. (water will not be oxidized or reduced in this
cell). Calculate the net Eo value.
b) Identify the oxidizing agent .
c) Identify the reducing agent .
d) Identify this as an electrolytic or an electrochemical cell based on your Net Eo calculation.
e) Is this reaction spontaneous?
8. What are the two common purposes type III electrolytic cells are used for?
9. If you want to plate something with a metal, does it need to be the anode or the cathode? Explain
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BCLN CHEMISTRY 12 - Rev. July/2018
Answers:
Electrochemistry Hints:
10. The first 4 you just look up. The last 3 you will need to do some math balancing!
11. If a single element has a charge then the oxidation number IS that charge!
Electrochemistry Answers:
10. 0 0 +1 -2 +6 -1 +5
11. The change for each is as follows: +5, -1, +8, 0, -2
The Standard Reduction Table Hints:
9b) This will be the reverse order of the oxidizing agents
The Standard Reduction Table Answers:
8 a) Ni
 Ni2+ + 2Cl-
+ Cl2(g)
b) 2Al + 3Br2(g)
 2 Al3+ + 6Br-
c) 2 MnO4- + 16H+ + 10 I-  2 Mn2+ + 8 H2O + 5 I2(g)
d) 4 Au3+ + 6 H2O  4 Au + 3 O2(g) + 12 H+
Balancing Reactions Answers:
+ 10 H+  4 Cr3+ + 3 SO32- + 5 H2O
2. 2 Cr2O72- +
3 S(s)
3. 10 MnO2 +
6 BrO3- +
4. 3 Hg(l)
+
5. 4 PO33- +
2 NO3- +
1 ClO4-
4 OH-  10 MnO4- + 3 Br2(l) + 2 H2O
8 H+  3 Hg2+ + 2 NO(g)
+ 4 H2O
 4 PO43- + 1 Cl-
6. 2 AuCl4- + 3 H2 + 6 OH-  2 Au(s)
+ 8 Cl- + 6 H2O
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BCLN CHEMISTRY 12 - Rev. July/2018
The Electrochemical Cell Answers:
3. 0
4. +4.52
5. +0.11
6. -0.11
Electrolytic Cells Answers:
2. -2.20
6. -0.30
7.a) -0.94
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12. +0.70
13. a) +1.06