7243258
Pregunta 1
Pregunta
What is the oxidation number of bromine in the BrO3- ion?
Respuesta
-
A) -1
-
B) +1
-
C) +3
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D) +5
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E) +7
Pregunta 2
Pregunta
What is the oxidation number of sulfur in the HSO4- ion?
Respuesta
-
A) -2
-
B) +1
-
C) +2
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D) +4
-
E) +6
Pregunta 3
Pregunta
Which element is oxidized in the reaction below?
Fe(CO)5 (l) + 2HI (g) → Fe(CO)4I2 (s) + CO (g) + H2 (g)
Respuesta
-
A) Fe
-
B) C
-
C) O
-
D) H
-
E) I
Pregunta 4
Pregunta
Which element is reduced in the reaction below?
Fe(CO)5 (l) + 2HI (g) → Fe(CO)4I2 (s) + CO (g) + H2 (g)
Respuesta
-
A) Fe
-
B) C
-
C) O
-
D) H
-
E) I
Pregunta 5
Pregunta
Which of the following reactions is a redox reaction?
(a) K2CrO4 + BaCl2 → BaCrO4 + 2KCl
(b) Pb22+ + 2Br- → PbBr
(c) Cu + S → CuS
Respuesta
-
A) (a) only
-
B) (b) only
-
C) (c) only
-
D) (a) and (c)
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E) (b) and (c)
Pregunta 6
Pregunta
Which one of the following reactions is a redox reaction?
Respuesta
-
A) NaOH + HCl → NaCl + H2O
-
B) Pb2+ + 2Cl- → PbCl2
-
C) AgNO3 + HCl → HNO3 + AgCl
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D) None of the above is a redox reaction.
Pregunta 7
Pregunta
Which substance is the reducing agent in the following reaction?
Fe2S3 + 12HNO3 → 2Fe(NO3)3 + 3S + 6NO2 + 6H2O
Respuesta
-
A) HNO3
-
B) S
-
C) NO2
-
D) Fe2S3
-
E) H2O
Pregunta 8
Pregunta
What is the coefficient of the permanganate ion when the following equation is balanced?
MnO4- + Br- → Mn2+ + Br2 (acidic solution)
Respuesta
-
A) 1
-
B) 2
-
C) 3
-
D) 5
-
E) 4
Pregunta 9
Pregunta
What is the coefficient of Fe3+ when the following equation is balanced?
CN- + Fe3+ → CNO- + Fe2+ (basic solution)
Respuesta
-
A) 1
-
B) 2
-
C) 3
-
D) 4
-
E) 5
Pregunta 10
Pregunta
The purpose of the salt bridge in an electrochemical cell is to __________.
Respuesta
-
A) maintain electrical neutrality in the half-cells via migration of ions.
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B) provide a source of ions to react at the anode and cathode.
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C) provide oxygen to facilitate oxidation at the anode.
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D) provide a means for electrons to travel from the anode to the cathode.
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E) provide a means for electrons to travel from the cathode to the anode.
Pregunta 11
Pregunta
Which transformation could take place at the anode of an electrochemical cell?
Respuesta
-
A) NO → NO3-
-
B) CO2 → Cr2O42-
-
C) VO2+ → VO2+
-
D) H2AsO4 → H3AsO3
-
E) O2 → H2O2
Pregunta 12
Pregunta
Which transformation could take place at the cathode of an electrochemical cell?
Respuesta
-
A) MnO2 → MnO4-
-
B) Br2 → BrO3-
-
C) NO → HNO2
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D) HSO4- → H2SO3
-
E) Mn2+ → MnO4-
Pregunta 13
Pregunta
Which of the halogens in Table 20.1 is the strongest oxidizing agent?
Respuesta
-
A) Cl2
-
B) Br2
-
C) F2
-
D) I2
-
E) All of the halogens have equal strength as oxidizing agents.
Pregunta 14
Pregunta
Which one of the following types of elements is most likely to be a good oxidizing agent?
Respuesta
-
A) alkali metals
-
B) lanthanides
-
C) alkaline earth elements
-
D) transition elements
-
E) halogens
Pregunta 15
Pregunta
Which one of the following is the best oxidizing agent?
Respuesta
-
A) H2
-
B) Na
-
C) O2
-
D) Li
-
E) Ca
Pregunta 16
Pregunta
Which of the following reactions will occur spontaneously as written?
Respuesta
-
A) Sn4+ (aq) + Fe3+ (aq) → Sn2+ (aq) + Fe2+ (aq)
-
B) 3Fe (s) + 2Cr3+ (aq) → 2Cr (s) + 3Fe2+ (aq)
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C) Sn4+ (aq) + Fe2+ (aq) → Sn2+ (aq) + Fe (s) ← I chose this one
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D) 3Sn4+ (aq) + 2Cr (s) → 2Cr3+ (aq) + 3Sn2+ (aq)
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E) 3Fe2+ (aq) → Fe (s) + 2Fe3+ (aq)
Pregunta 17
Pregunta
Consider an electrochemical cell based on the reaction:
2H+ (aq) + Sn (s) → Sn2+ (aq) + H2 (g)
Which of the following actions would change the measured cell potential?
Respuesta
-
A) increasing the pH in the cathode compartment
-
B) lowering the pH in the cathode compartment
-
C) increasing the [Sn2+] in the anode compartment
-
D) increasing the pressure of hydrogen gas in the cathode compartment
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E) Any of the above will change the measure cell potential.
Pregunta 18
Pregunta
Consider an electrochemical cell based on the reaction:
2H+ (aq) + Sn (s) → Sn2+ (aq) + H2 (g)
Which of the following actions would not change the measured cell potential?
Respuesta
-
A) lowering the pH in the cathode compartment
-
B) addition of more tin metal to the anode compartment
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C) increasing the tin (II) ion concentration in the anode compartment
-
D) increasing the pressure of hydrogen gas in the cathode compartment
-
E) Any of the above will change the measured cell potential.
Pregunta 19
Pregunta
Cathodic protection of a metal pipe against corrosion usually entails
Respuesta
-
A) attaching an active metal to make the pipe the anode in an electrochemical cell.
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B) coating the pipe with another metal whose standard reduction potential is less negative than that of the pipe.
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C) attaching an active metal to make the pipe the cathode in an electrochemical cell.
-
D) attaching a dry cell to reduce any metal ions which might be formed.
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E) coating the pipe with a fluoropolymer to act as a source of fluoride ion (since the latter is so hard to oxidize).
Pregunta 20
Pregunta
One of the differences between a voltaic cell and an electrolytic cell is that in an electrolytic cell __________.
Respuesta
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A) an electric current is produced by a chemical reaction
-
B) electrons flow toward the anode
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C) a nonspontaneous reaction is forced to occur
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D) O2 gas is produced at the cathode
-
E) oxidation occurs at the cathode
Pregunta 21
Pregunta
__________ is reduced in the following reaction:
Cr2O72- + 6S2O32- + 14H+ → 2Cr3+ + 3S4O62- + 7H2O
Respuesta
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A) Cr6+
-
B) S2+
-
C) H+
-
D) O2-
-
E) S4O62-
Pregunta 22
Pregunta
Which substance is serving as the oxidizing agent in the following reaction?
14H+ + Cr2O72- + 3Ni → 3Ni2+ + 2Cr3+ + 7H2O
Respuesta
-
A) Ni
-
B) H+
-
C) Cr2O72-
-
D) H2O
-
E) Ni2+
Pregunta 23
Pregunta
__________ electrons appear in the following half-reaction when it is balanced.
S4O62- → S2O32-
Respuesta
-
A) 6
-
B) 2
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C) 4
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D) 1
-
E) 3
Pregunta 24
Pregunta
The balanced half-reaction in which dichromate ion is reduced to chromium metal is a __________ process.
Respuesta
-
A) two-electron
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B) six-electron
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C) three-electron
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D) four-electron
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E) twelve-electron
Pregunta 25
Pregunta
The electrode at which oxidation occurs is called the __________.
Respuesta
-
A) oxidizing agent
-
B) cathode
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C) reducing agent
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D) anode
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E) voltaic cell
Pregunta 26
Pregunta
In a voltaic cell, electrons flow from the __________ to the __________.
Respuesta
-
A) salt bride, anode
-
B) anode, salt bridge
-
C) cathode, anode
-
D) salt bridge, cathode
-
E) anode, cathode
Pregunta 27
Pregunta
The standard cell potential (E°cell) for the voltaic cell based on the reaction below is __________ V.
Sn2+ (aq) + 2Fe3+ (aq) → 2Fe2+ (aq) + Sn4+ (aq)
Respuesta
-
A) +0.46
-
B) +0.617
-
C) +1.39
-
D) -0.46
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E) +1.21
Pregunta 28
Pregunta
The standard cell potential (E°cell) for the voltaic cell based on the reaction below is __________ V.
Cr (s) + 3Fe3+ (aq) → 3Fe2+ (aq) + Cr3+ (aq)
Respuesta
-
A) -1.45
-
B) +2.99
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C) +1.51
-
D) +3.05
-
E) +1.57
Pregunta 29
Pregunta
The standard cell potential (E°cell) of the reaction below is +0.126 V. The value of ΔG° for the reaction is __________ kJ/mol.
Pb (s) + 2H+ (aq) → Pb2+ (aq) + H2 (g)
Respuesta
-
A) -24.3
-
B) +24.3
-
C) -12.6
-
D) +12.6
-
E) -50.8
Pregunta 30
Pregunta
The standard cell potential (E°cell) of the reaction below is -0.34 V. The value of ΔG° for the reaction is __________ kJ/mol.
Cu (s) + 2H+ (aq) → Cu2+ (aq) + H2 (g)
Respuesta
-
A) -0.34
-
B) +66
-
C) -130
-
D) +130
-
E) none of the above
Pregunta 31
Pregunta
The standard cell potential (E°cell) of the reaction below is +1.34 V. The value of ΔG° for the reaction is __________ kJ/mol.
3Cu (s) + 2MnO4- (aq) + 8H+ (aq) → 3Cu2+ (aq) + 2MnO2 (s) + 4H2O (l)
Respuesta
-
A) -24.3
-
B) +259
-
C) -259
-
D) +776
-
E) none of the above
Pregunta 32
Pregunta
Galvanized iron is iron coated with __________.
Respuesta
-
A) magnesium.
-
B) zinc.
-
C) chromium.
-
D) phosphate.
-
E) iron oxide.
Pregunta 33
Pregunta
The standard cell potential (E°) of a voltaic cell constructed using the cell reaction below is 0.76 V:
Zn (s) + 2H+ (aq) → Zn2+ (aq) + H2 (g)
With PH2 = 1.0 atm and [Zn2+] = 1.0 M, the cell potential is 0.66 V. The concentration of H+ in the cathode compartment is __________ M.
Respuesta
-
A) 2.0 × 10-2
-
B) 4.2 × 10-4
-
C) 1.4 × 10-1
-
D) 4.9 × 101
-
E) 1.0 × 10-12
Pregunta 34
Pregunta
A voltaic cell is constructed with two silver-silver chloride electrodes, where the half-reaction is
AgCl (s) + e- → Ag (s) + Cl- (aq) E° = +0.222 V
The concentrations of chloride ion in the two compartments are 0.0222 M and 2.22 M, respectively. The cell emf is __________ V.
Respuesta
-
A) 0.212
-
B) 0.118
-
C) 0.00222
-
D) 22.2
-
E) 0.232
Pregunta 35
Pregunta
The standard cell potential (E°cell) for the reaction below is +0.63 V. The cell potential for this reaction is __________ V when [Zn2+] = 3.5 M and [Pb2+] = 2.0 × 10-4 M.
Pb2+ (aq) + Zn (s) → Zn2+ (aq) + Pb (s)
Respuesta
-
A) 0.50
-
B) 0.84
-
C) 0.39
-
D) 0.76
-
E) 0.63
Pregunta 36
Pregunta
The standard emf for the cell using the overall cell reaction below is +2.20 V:
2Al (s) + 3I2 (s) → 2Al3+ (aq) + 6I- (aq)
The emf generated by the cell when [Al3+] = 4.5 × 10-3 M and [I-] = 0.15 M is ________ V.
Respuesta
-
A) 2.20
-
B) 2.32
-
C) 2.10
-
D) 2.39
-
E) 2.23
Pregunta 37
Pregunta
The most difficult species to reduce and the poorest oxidizing agent is __________.
Respuesta
-
A) Fr+
-
B) F-
-
C) Li+
-
D) He
Pregunta 38
Pregunta
In a half reaction the amount of a substance that is reduced or oxidized is directly proportional to the number of electrons generated in the cell.
Respuesta
-
True
-
False
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