Download A) Sn4+ → Sn2+ + 2e

1. Which half–cell reaction correctly represents reduction?
A)
B)
C)
D)
E)
Sn4+ ® Sn2+ + 2e –
Sn2+ ® Sn4+ + 2e –
Sn4+ + 2e – ® Sn2+
Sn2+ + 2e – ® Sn4+
Sn4+ + Sn2+ ® Sn6+ + 2e –
2.
6. In the half–cell reaction Ca ®Ca2+ + 2e –, which is true
of the calcium atom?
A)
B)
C)
D)
E)
It gains protons
It loses protons
It gains electrons
It loses electrons
It loses an electron and gains a proton
7. Which half–reaction correctly represents oxidation?
A)
B)
C)
D)
E)
In the electrochemical cell, Co/Co 2+||Sn 2+/Sn,
which substance is the electrode that gains weight?
A) Co
C) Sn
E) both Sn and Co
B) Co2+
D) Sn2+
Br 2 ® 2 Br – + 2e –
Br 2 + 2e – ® 2 Br –
H 2 ® 2 H + + 2e –
H2 + 2e – ® 2 H+
H2 + 2 H+ ® 2e – + 4 H
8.
3. For the following question refer to the table below.
What electrode gains weight in the electrochemical cell?
Fe/Fe 2+|| Ag+ /Ag
What is the E° for the reaction:
Hg ® Hg2+ + 2e –?
A) +1.65 B) +0.85 C) –0.05 D) –0.85 E) –1.65
4. In the reaction
Sn2+(aq) + 2 Ag + (aq) ® Sn4+(aq) + 2 Ag(s)
What is the half–reaction equation for the oxidizing
agent above?
A) Sn2+ ® Sn4+ + 2e –
C) Sn2+ + 2e – ® Sn4+
E) Sn2+ + Sn4+ ® 2e –
B) Ag+ + e – ® Ag
D) Ag+ ® Ag + e–
5. The function of the salt bridge in an electrochemical cell
is to
A)
B)
C)
D)
E)
increase the cell voltage
maintain electrical neutrality
increase the oxidation–reduction rate
supply a travel pathway for electrons
increase the rate of attainment of equilibrium
A)
B)
C)
D)
E)
Ag
Ag+
Fe
Fe 2+
It cannot be determined from the information given
9. Which half-reaction would occur at the cathode of an
electrochemical cell?
A)
B)
C)
D)
E)
Au ® Au3+ + 3e –
Au + 3e– ® Au3+
Au3+ ® Au + 3e–
Au 3+ + 3e – ® Au
Au + Au 3+ ® 3e – + Au3+
10. Which substance is the electrode that gains weight
during the operation of this electrochemical cell?
Cr/Cr 3+ || Pb 2+/Pb
A) Cr
C) Pb
E) both Cr and Pb
B) Cr 3+
D) Pb2+
A) Cl 2
B) Br 2
C) Hg2+
B) Br –
C) Cr
D) Cr 3+
E) Al
D) I 2
Cu ®Cu2+ + 2e –
E) I –
12. Which is the most easily oxidized?
A) Cl –
B) Br 2
15. What is the oxidation potential for the reaction?
11. Which is the most easily reduced?
A) Cl 2
14. Which is the strongest reducing agent?
C) Hg(l) D) I –
13. Which is the strongest oxidizing agent?
A) -0.52 V
C) +0.18 V
E) +0.52 V
B) -0.34 V
D) +0.34 V
16. What is the standard reduction potential of Na if the
standard hydrogen half-cell potential is changed from
0.00 to +0.40 volts?
E) Br 2
A) -3.11 V
C) -2.31 V
E) +3.11 V
B) -2.71 V
D) 0.00 V
17. What is the electrode potential of the standard hydrogen
half-cell reaction?
A) HNO 3
C) Cu
E) H+
B) Ag+
D) H2
A) -0.83 V
C) +0.83 V
E) +1.23 V
B) 0.00 V
D) +0.96 V
18. What is the standard electrode potential, E°, for this
half-reaction?
2Ag+ + 2e – ® 2Ag
22. In an electrochemical cell, the positive ions go from the
A)
B)
C)
D)
E)
anode to the cathode through the wire
cathode to the anode through the wire
anode to the cathode through the salt bridge
cathode to the anode through the salt bridge
cathode to the anode through the wire and anode to
the cathode through the salt bridge
23. In an electrochemical cell, the electrons go from the
A) –0.80 V
C) +0.40 V
E) +1.60 V
B) –1.60 V
D) +0.80 V
19. For the following question refer to the table below.
A)
B)
C)
D)
E)
anode to the cathode through the wire
cathode to the anode through the wire
anode to the cathode through the salt bridge
cathode to the anode through the salt bridge
anode to the cathode through the wire and cathode
to the anode through the salt bridge
24. Which is the cathode of this electrochemical cell?
Cr + Au3+ ® Cr 3+ + Au
What is the E° for this reaction?
2 Cr ® 2 Cr 3+ + 6e
A) +1.48 V
C) 0.00 V
E) –1.48 V
–
B) +0.74 V
D) –0.74 V
20. The negative ions go to which electrode in the voltaic
cell
Mg/Mg2+||Ag+ /Ag?
A) Ag
C) Mg
E) both Ag and Mg
B) Ag+
D) Mg 2+
21. To which electrode do the electrons move in the cell
A)
B)
C)
D)
E)
Cr
Au3+
Cr 3+
Au
It cannot be determined unless the potentials are
known
25. Base your answer on the table below.
Zn/Zn2+||Pb 2+/Pb?
A)
B)
C)
D)
E)
Pb
Pb2+
Zn
Zn2+
It cannot be determined unless the potentials are
known.
Which is an oxidizing agent capable of converting Mg
to Mg2+, but not Zn to Zn2+?
A) Al 3+
C) Ba2+
E) None of the above
B) Ba
D) Mn
26. Base your answer on the table below.
29. Base your answer on the table below.
Which statement is true?
A)
B)
C)
D)
E)
Fe 3+ reduces Fe2+ to Fe.
Fe oxidizes Fe 2+ to Fe 3+.
Fe reduces Fe 3+ to Fe 2+.
Fe 3+ oxidizes Fe to Fe2+.
Fe 2+ reduces Fe3+ to Fe.
27. Base your answer on the table below.
Ions of the transition elements are generally colored.
What color will the final solution be when a solution of
Fe(NO 3) 2 is mixed with an acid solution of KMnO 4?
A) clear
C) purple
E) brown
30. Base your answer on the table below.
Which substance is most easily oxidized?
A) Sn2+
B) Sn4+
C) Nb
D) Nb3+
B) green
D) yellow
E) 2e –
28. Base your answer on the table below.
Which statement is true?
Which is an agent which oxidizes H 2 to H + , but not
Hg to Hg2+?
A) Br 2
B) Cl –
C) Cu
D) I 2
E) Mn 2+
A) Br 2 will oxidize the chloride ion, but not the iodide
ion.
B) Br2 will oxidize the iodide ion, but not the
chloride ion.
C) I 2 will oxidize the chloride ion, but not the
bromide ion.
D) I 2 will oxidize the chloride ion, but not the
bromide ion.
E) Cl 2 will oxidize the bromide ion, but not the iodide
ion.
31. Base your answer on the table below.
What is the net voltage of this electrochemical cell?
Cr/Cr 3+ || Ni 2+/Ni
A) 2.00 V
C) 0.74 V
E) –1.00 V
B) 1.00 V
D) 0.48 V
32. Base your answer on the table below.
34. Base your answer on the table below.
Which statement is true? Bromide ion, Br –(aq), reduces
A)
B)
C)
D)
E)
I –(aq), but not fluorine, F 2(g).
F2(g), but not chlorine, Cl 2(g).
I 2(s), but not fluoride ion, F–(aq).
Cl 2(g), but not fluoride ion, F –(aq).
none of these other ions or gases.
35. Base your answer on the table below.
What is the net potential developed by an
electrochemical cell with these half reactions?
A) +0.89 V
C) +0.63 V
E) –0.89 V
B) +0.76 V
D) –0.63 V
33.
When magnesium metal is added to an unknown acid
solution, a brownish colored gas is observed. What is
most likely to be the unknown acid?
Which will react with hydrochloric acid?
A) Al and Ca
C) Ca and Cu
E) Ca only
B) Al and Cu
D) Cr and Cu
A)
B)
C)
D)
E)
Water
Nitrous acid
Hydrochloric acid
Acid and permanganate ion
Nitric acid
36. Base your answer on the table below.
39. Base your answer on the table below.
Which statement is true?
Which species will reduce Cu 2+ to Cu?
A) Ag
C) Cl –
E) Sn2+
B) Au
D) H+ + MnO4–
37. Base your answer on the table below.
What is the initial net cell potential for the
electrochemical cell, Ga/Ga 3+||Hg2+/Hg?
A) –0.29 V
C) 1.41 V
E) 3.67 V
B) 0.29 V
D) 1.43 V
A)
B)
C)
D)
E)
Al 3+ will oxidize Cr but not Ca.
Al 3+ will oxidize Ca but not Cr.
Ca2+ will oxidize Cr but not Al.
Ca2+ will oxidize Al but not Cr.
Cr 3+ will oxidize Al but not Ca.
40. As the reaction in an electrochemical cell approaches
equilibrium, the rate of the anode reaction
A)
B)
C)
D)
E)
decreases to zero
decreases somewhat
increases somewhat
increases a large amount
remains the same
41. What is the net potential (E°) for this reaction at
equilibrium?
2 Fe 3+ + 2 I – «2 Fe 2+ + I 2
38. Base your answer on the table below.
What is the net cell potential of the electrochemical cell
Fe/Fe 2+||Cu 2+/Cu?
A) +1.58 V
C) +0.11 V
E) –0.79 V
B) +0.79 V
D) –0.11 V
A) 0.00 volts
C) 1.00 volts
E) 2.08 volts
B) 0.23 volts
D) 1.31 volts
42. In order for a redox reaction to be at equilibrium, the
potential (E°) must be
A) less than –1
C) 0
E) greater than 1
B) between 0 and –1
D) between 0 and 1
43. What is the potential (E°) of an electrochemical cell
which has reached equilibrium?
A) less than 0
C) between 0 and 1
E) greater than 1
B) 0
D) 1
44. As the reaction in an electrochemical cell approaches
equilibrium, the voltage of the cell
A)
B)
C)
D)
E)
49. Which substance is reduced?
5 HSO 3– + 2 IO3– ® 5 SO 42– + I 2 + 3 H+ + H2O
increases
decreases
remains the same
increases, then decreases
decreases, then increases
A)
B)
C)
D)
E)
45. For the following question refer to the table below.
I2
IO3–
SO 42–
HSO 3–
This is not a redox reaction
50. To electroplate copper on a carbon rod, the carbon rod
must be
A)
B)
C)
D)
E)
What is the cell potential, Eº, at equilibrium for the cell:
Pb/Pb 2+||Cu 2+/Cu?
A) +0.47 B) +0.21 C) 0.00
D) –0.21 E) –0.47
the anode
the cathode
in acid solution
in melted copper
the positive electrode
51.
46. Which substance is oxidized?
2 Cr + 3 Pb(NO 3) 2 ® 2 Cr(NO 3) 2 + 3 Pb
A) Cr
C) Cr(NO 3) 2
E) NO 3–
B) Pb
D) Pb(NO 3) 2
47. What gas is released when a piece of zinc, Zn, is added
to a hydrochloric acid solution, HCl(aq)?
A)
B)
C)
D)
E)
Chlorine, Cl 2
Hydrogen, H2
Zinc chloride, ZnCl 2
Hydrogen chloride, HCl
Oxygen, O 2
48. Which substance is oxidized?
Pb(NO 3) 2 ®PbO 2 + 2 NO 2
A)
B)
C)
D)
E)
NO 2
PbO 2
Pb(NO 3) 2
NO 3–
This is not a redox reaction
Which is the strongest oxidizing agent?
A) Sn4+(aq)
C) Al 3+(aq)
E) Sn(s)
B) Sn2+(aq)
D) Al(s)
52. Which is the reduced substance
Mg(s) + 2 HCl(aq) ® MgCl 2(aq) + H 2(g)
A)
B)
C)
D)
E)
H2(g)
HCl(aq)
Mg(s)
MgCl 2(aq)
This is not a redox reaction
53. Which is the substance that is oxidized?
2 KI(aq) + Cl2(aq) ® 2 KCl(aq) + I2(aq)
A)
B)
C)
D)
E)
Cl 2
I2
KCl
KI
This is not a redox reaction
54. Which is the substance which is reduced?
59. Consider the unbalanced redox equation skeleton.
SnCl 2(aq) + 2 FeCl3(aq) ® 2 FeCl 2(aq) + SnCl4(aq)
A)
B)
C)
D)
E)
FeCl 2(aq)
FeCl3(aq)
H2(g)
SnCl 2(aq)
This is not a redox reaction
55. Which substance is reduced?
2 Cr + 3 Pb(NO 3) 2 ®2 Cr(NO 3) 2 + 3 Pb
A) Cr
C) Cr(NO 3) 2
E) NO 3–
B) Pb
D) Pb(NO 3) 2
56. Which reaction is balanced?
A)
B)
C)
D)
E)
HBr + H 2SO 4 ® Br 2 + SO 2 + H2O
2 HBr + H2SO 4 ® Br2 + SO 2 + 2 H2O
2 HBr + 2 H 2SO 4 ® Br 2 + 2 SO 2 + 4 H2O
4 HBr + H 2SO 4 ® 2 Br 2 + SO 2 + 2 H2O
4 HBr + H 2SO 4 ® 2 Br 2 + SO 2 + 2 H2O + 8e–
57.
Pb + Cr2O72– + H+ ® Pb2+ + Cr 3+ + H2O
Which is the balanced overall reaction?
A)
B)
C)
D)
Pb + Cr2O72– + H+ ® Pb2+ + Cr 3+ + H2O
Pb + Cr2O72– + 14 H+ ® Pb2+ + 2Cr 3+ + 7 H2O
Pb + Cr2O72– + H+ + 6e – ® Pb2+ + Cr 3+ + H2O
2 Pb + Cr2O72– + 14 H+ ® 2 Pb2+ + 2 Cr 3+ + 7 H2
O
E) 3 Pb + Cr 2O 72– + 14 H+ ® 3 Pb2+ + 2 Cr3+ + 7
H 2O
60. Consider the unbalanced redox equation skeleton.
Pb + Cr2O72– + H+ ® Pb2+ + Cr 3+ + H2O
Which is the balanced reduction reaction?
A)
B)
C)
D)
E)
Pb ® Pb2+ + 2e –
Pb2+ + 2e – ® Pb
2Cr 3+ + 7H2O ® Cr 2O72– + 14H+ + 6e –
Cr2O 72– + 14H+ + 6e – ® 2Cr3+ + 7H2O
Cr 2O72– + 6e – ® 2Cr 3+ + 7O2–
61. Consider the unbalanced redox equation skeleton.
Pb + Cr2O72– + H+ ® Pb2+ + Cr 3+ + H2O
Which is the balanced oxidation reaction?
Which reaction is balanced?
A)
B)
C)
D)
Cu + MnO 4– + H+ ® Cu2+ + Mn 2+ + H2O
Cu + MnO 4– + 8 H+ ® Cu2+ + Mn 2+ + 4 H2O
5Cu + MnO 4– + 8 H+ ® 5 Cu2+ + Mn 2+ + 4 H2O
5Cu + 2 MnO 4– + 16 H+ ® 5 Cu 2+ + 2 Mn 2+ +
8 H2O
E) 5Cu + 2 MnO 4– + 16 H+ ® 5 Cu2+ + 2 Mn 2+ + 8
H2O + 10e–
58. Which is correctly balanced?
A)
B)
C)
D)
E)
Ag + 2 HNO 3 ® AgNO3 + NO + H2O
Ag + 4 HNO 3 ® AgNO3 + 7 NO + 2H2O
3 Ag + 4 HNO 3 ® 3 AgNO3 + NO + 2 H2O
Ag + 2 HNO 3 ® AgNO3 + NO + 2 H2O
3 Ag + 4 HNO 3 ® 3 AgNO3 + NO + 2 H2O + 3e–
A)
B)
C)
D)
E)
Pb ® Pb2+ + 2e –
Pb2+ + 2e – ® Pb
2Cr 3+ + 7H2O ® Cr 2O72– + 14H+ + 6e –
Cr 2O72– + 14H+ + 6e – ® 2Cr 3+ + 7H2O
Cr 2O72– + 6e – ® 2Cr 3+ + 7O2–
62. What is the coefficient of phosphorus, P, when the
equation is balanced using small whole numbers?
H2SO 4 + P ® H3PO 4 + H2O + SO 2
A) 1
B) 2
C) 10
D) 4
E) 5
63. How many moles of zinc, Zn, will reduce one mole of
vanadium from V5+ to V 2+? The unbalanced expression
is
V5+(aq) + Zn(s) ® V2+(aq) + Zn 2+(aq)
A) 1 1/ 2
B) 2
C) 2 1/ 2
D) 2/ 5
E) 4/ 5
64. Which substance is reduced?
2 NaOH + H 2SO 4 ®Na2SO 4 + 2 H2O
A)
B)
C)
D)
E)
H2O
NaOH
H2SO 4
Na2SO 4
This is not a redox reaction
65. Which substance is oxidized?
2 NaOH + H 2SO 4 ®Na2SO 4 + 2 H2O
A)
B)
C)
D)
E)
H2O
NaOH
H2SO 4
Na2SO 4
This is not a redox reaction
66. Which is a redox reaction?
A)
B)
C)
D)
E)
68. A 1.0 M solution of ZnCl 2 is electrolyzed. Which are
the correct half–reactions?
BaSO 4 ® Ba2+ + SO 42–
Cu(NO 3) 2 + H2S ® CuS + 2 HNO 3
CaCO 3 ® CaO + CO 2
2 Al + 6 H2O ® 2 Al(OH) 3 + 3 H2
NH 4+ ® H+ + NH 3
67. A 1.0 M solution of NiBr2 is electrolyzed. Which are
the correct half–reactions?
A) Anode: Br 2 + 2e – ® 2 Br – Cathode: Ni ® Ni 2+
+ 2e –
B) Anode: 2 Br – ® Br 2 + 2e – Cathode: 2 H 2O + 2e
– ® H 2 + 2 OH –
C) Anode: 2 H2O ® O2 + 4 H+ + 4e – Cathode: 2
Ni 2+ + 4e – ® 2 Ni
D) Anode: 2 H2O ® O2 + 4 H+ + 4e – Cathode: 4 H
2 O + 4e – ® 2 H 2 + 4 OH –
E) Anode: 2 Br – ® Br2 + 2e – Cathode: Ni 2+ + 2e
– ® Ni
A) Anode: 2 Cl – ® Cl 2 + 2e – Cathode: Zn 2+ + 2e –
® Zn
B) Anode: 2 Cl – ® Cl 2 + 2e – Cathode: 2 H 2O + 2e
– ® H 2 + 2 OH –
C) Anode: 2 H 2O ® O 2 + 4 H+ + 4e – Cathode: 2
Zn2+ + 4e – ® 2 Zn
D) Anode: 2 H2O ® O2 + 4 H+ + 4e – Cathode: 4 H
2 O + 4e – ® 2 H 2 + 4 OH –
E) Anode: Cl 2 + 2e – ® 2 Cl – Cathode: Zn ® Zn
2+ + 2e –
69. What are the anode and cathode half–reactions for the
electrolysis of fused (melted) NaCl?
A) Anode: 2 Cl– ® Cl 2 + 2e – Cathode: 2 Na+ +
2e – ® 2 Na
B) Anode: 2 Cl – ® Cl 2 + 2e – Cathode: 2 H 2O + 2e
– ® H 2 + 2 OH –
C) Anode: 2 H2O ® O2 + 4 H+ + 4e – Cathode: 4
Na+ + 4e – ® 4 Na
D) Anode: 2 H2O ® O2 + 4 H+ + 4e – Cathode: 4 H
2 O + 4e – ® 2 H 2 + 4 OH –
E) Anode: Cl 2 + 2e – ® 2 Cl – Cathode: 2 Na ® 2
Na+ + 2e –
70. What are the anode and cathode reactions during the
electrolysis of fused KBr?
–
A) Anode:
2 H2O ® O2 + 4 H+ + 4e Cathode: 4
K+ + 4e – ® 4 K
B) Anode: 2 Br – ® Br 2 + 2e – Cathode: 2 H 2O +
2e – ® H2 + 2 OH –
C) Anode: Br 2 + 2e – ® 2 Br – Cathode: 2 K ® 2
K+ + 2e –
D) Anode: 2 H2O ® O2 + 4 H+ + 4e – Cathode: 4 H
2 O + 4e – ® 2 H 2 + 4 OH –
E) Anode: 2 Br – ® Br2 + 2e – Cathode: 2 K + + 2e
–® 2K
71. An electrolytic cell differs from a chemical (or voltaic)
cell in that the electrolytic cell
A)
B)
C)
D)
E)
is exothermic
produces an electric current
uses an applied electric current
involves oxidation and reduction reactions
occurs spontaneously
72. One mole of electrons is passed through aqueous
systems containing the stated ion and two inert
electrodes. Which will have the greatest mass of
deposited element?
A)
C)
E)
56Fe 3+
112Cd 2+
B)
D)
108Ag +
Mg 2+(aq) + 2 Cl–(aq) ® Mg(s) + Cl 2(l)
How many grams of magnesium metal are produced by
the electrolysis of 0.10 mole of melted magnesium
chloride, MgCl2 ?
C) 2.4
D) 4.8
E) 12
74. What is the charge and the reaction occurring at the
anode of an electrolysis reaction?
A)
B)
C)
D)
E)
(+), oxidation
(+), reduction
(–), reduction
(–), oxidation
reactions only occur at the cathode
75. In the electrolysis of molten CaCl 2 , the species
oxidized is
A)
B)
C)
D)
E)
Ca
Ca2+
Cl –
Cl 2
Oxidation does not occur
76. In the electrolysis of aqueous copper (II) bromide
solution, CuBr 2(aq), 1.00 gram of Cu is deposited at the
cathode. How many grams of bromine are formed at the
anode?
A) 2.00 grams
C) 3.00 grams
E) 159 grams
B) 2.52 grams
D) 79.9 grams
B) at the anode
D) at the salt bridge
78. At the cathode during electrolysis, what is its charge
and what type of reaction occurs.
A)
B)
C)
D)
E)
(–), oxidation
(+), oxidation
(–), reduction
(+), reduction
no reaction occurs at the cathode
A) at the wire
C) at the cathode
E) in solution
73. Given the equation:
B) 0.24
A) in the wire
C) at the cathode
E) in solution
79. Electroplating occurs during electrolysis
197Au 3+
207Pb2+
A) 0.12
77. Electroplating always takes place
B) at the anode
D) at the salt bridge
80. The mass of a metal deposited at the cathode during
electroplating is proportional to the
A)
B)
C)
D)
radius of the cation
activity of the metal
temperature of the electrolyte
quantity of electrical charge passed through the
cell
E) molarity of the ions in solution
81. If fused silver chloride, AgCl, is electrolyzed, the Ag+
ions are
A)
B)
C)
D)
E)
reduced at the negative electrode
reduced at the positive electrode
oxidized at the negative electrode
oxidized at the positive electrode
neither oxidized nor reduced
82. From which aqueous system will one mole of electrons
deposit the greatest mass of the element ?
A)
C)
E)
207Pb2+
59Ni 2+
B)
D)
108Ag +
56Fe 2+
27Al 3+
83. How many grams of copper metal are deposited from a
solution of copper (II) sulfate, CuSO 4 , by 0.500 mole
of electrons?
A) 15.9 g
C) 47.7 g
E) 127 g
B) 31.8 g
D) 63.5 g
Answer Key
AP Chemistry Electrochemistry Review
1.
C
37.
C
73.
C
2.
C
38.
B
74.
A
3.
D
39.
B
75.
C
4.
B
40.
B
76.
B
5.
B
41.
A
77.
C
6.
D
42.
C
78.
C
7.
C
43.
B
79.
C
8.
A
44.
B
80.
D
9.
D
45.
C
81.
A
10.
C
46.
A
82.
B
11.
A
47.
B
83.
A
12.
D
48.
C
13.
A
49.
B
14.
E
50.
B
15.
B
51.
A
16.
C
52.
B
17.
B
53.
D
18.
D
54.
B
19.
B
55.
D
20.
C
56.
B
21.
A
57.
D
22.
C
58.
C
23.
A
59.
E
24.
D
60.
D
25.
A
61.
A
26.
C
62.
B
27.
C
63.
A
28.
D
64.
E
29.
D
65.
E
30.
B
66.
D
31.
D
67.
E
32.
C
68.
C
33.
A
69.
A
34.
D
70.
E
35.
E
71.
C
36.
E
72.
B