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Electrochemistry Review Questions
Choose the correct answer for each question.
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The oxidation number on nitrogen in a nitrate ion is:
?
-1
?
-3
?
-5
?
+3
?
+5
The sum of the oxidation numbers on all of the atoms in the formula of an acetate ion is equal to:
?
-2
?
-1
?
0
?
+1
?
+2
The standard hydrogen electrode is assigned a potential of _______ volts.
?
+2
?
+1
?
0
?
-1
?
-2
When chromium changes from an oxidation state of +3 to that of +6, the Cr
3+
must:
?
lose 3 electrons
?
lose 6 electrons
?
gain 3 electrons
?
gain 6 electrons
?
none of these
The equation that represents a reaction that is not a redox reaction is:
2H
2
+ O
2
--> 2H
2
O
Zn + CuSO
4
--> ZnSO
4
+ Cu
2H
2
O
2
--> 2H
2
O + O
2
H
2
O + CO
2
--> H
2
CO
3
?
Reaction 1
?
Reaction 2
?
Reaction 3
?
Reaction 4
?
All of these are redox reactions
In a reaction between hydrogen and oxygen and forming water, the oxidizing agent is:
?
hydrogen
?
oxygen
?
water
?
peroxide
?
there is no redox occuring in this reaction
In an electrochemical cell, ________________ occurs at the anode and ________________ occurs at the cathode.
?
oxidation, reduction
?
reduction, oxidation
?
oxidation, oxidation
?
reduction, reduction
?
Two of these are possible, depending on whether the cell is electrolytic or voltaic.
During the electroplating of silver, silver ions in solution:
?
are oxidized at the anode
?
are oxidized at the cathode
?
are reduced at the anode
?
are reduced at the cathode
?
remain in solution unchanged
The oxidation number on phosporous in aluminum phosphate, Al
2
(SO
4
)
3
is:
?
+2
?
+3
?
+5
?
+7
?
+8
Calculate
E
0
cell
for the voltaic cell composed of the following half cells:
Br
2
+ 2e
-
--> 2Br
-
(
E
0
= +1.07v)
?
E
0
cell
= + 0.73v
?
E
0
cell
= +1.41v
?
E
0
cell
= -0.73v
?
E
0
cell
= +0.39v
?
E
0
cell
= -0.39v
Elements that are very active reducing agents belong to Group:
?
1
?
2
?
16
?
17
?
18
The oxidation number of carbon in carbonic acid compared to its oxidation number in carbonous acid is:
?
smaller
?
greater
?
the same
In the unbalanced equation for the reaction:
NaCl + H
2
SO
4
+ MnO
2
--> Na
2
SO
4
+ MnSO
4
+ H
2
O + Cl
2
the element that undergoes oxidation is:
?
oxygen
?
sulfur
?
manganese
?
sodium
?
chlorine
In the unbalanced equation for the reaction:
NH
3
+ CuO ---> Cu + H
2
O + N
2
the element that undergoes reduction is:
?
nitrogen
?
oxygen
?
copper
?
hydrogen
?
none - this is not a redox reaction
In the reaction:
2NaOH + H
2
SO
4
--> Na
2
SO
4
+ 2H
2
O
the element that undergoes reduction is:
?
hydrogen
?
oxygen
?
sulfur
?
sodium
?
none - this is not a redox reaction
OK
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