Answer at the bottom of the page
20.1 Multiple-Choice
1) What is the oxidation number of bromine in the BrO3- ion?
A) -1
B) +1
C) +3
D) +5
E) +7
2) What is the oxidation number of nitrogen in the HNO3?
A) -1
B) +1
C) +3
D) +5
E) +7
3) What is the oxidation number of sulfur in the HSO4- ion?
A) -2
B) +1
C) +2
D) +4
E) +6
4) Which element is oxidized in the reaction below?
Fe(CO)5 (l) + 2HI (g) → Fe(CO)4I2 (s) + CO (g) + H2 (g)
A) Fe
B) C
C) O
D) H
E) I
5) Which element is reduced in the reaction below?
Fe(CO)5 (l) + 2HI (g) → Fe(CO)4I2 (s) + CO (g) + H2 (g)
A) Fe
B) C
C) O
D) H
E) I
6) Which element is oxidized in the reaction below?
Fe+2 + H+ + Cr2O7-2 → Fe+3 + Cr+3 + H2O
A) Fe
B) Cr
C) O
D) H
7) Which element is reduced in the reaction below?
Fe+2 + H+ + Cr2O7-2 → Fe+3 + Cr+3 + H2O
A) Fe
B) Cr
C) O
D) H
8) Which element is oxidized in the reaction below?
I- + MnO4- + H+ → I2 + MnO2 + H2O
A) I
B) Mn
C) O
D) H
9) Which element is reduced in the reaction below?
I- + MnO4- + H+ → I2 + MnO2 + H2O
A) I
B) Mn
C) O
D) H
10) Which of the following reactions is a redox reaction?
(a) K2CrO4 + BaCl2 → BaCrO4 + 2KCl
(b) Pb22+ + 2Br- → PbBr
(c) Cu + S → CuS
A) (a) only
B) (b) only
C) (c) only
D) (a) and (c)
E) (b) and (c)
11) Which one of the following reactions is a redox reaction?
A) NaOH + HCl → NaCl + H2O
B) Pb2+ + 2Cl- → PbCl2
C) AgNO3 + HCl → HNO3 + AgCl
D) None of the above is a redox reaction.
12) Which substance is the reducing agent in the following reaction?
Fe2S3 + 12HNO3 → 2Fe(NO3)3 + 3S + 6NO2 + 6H2O
A) HNO3
B) S
C) NO2
D) Fe2S3
E) H2O
13) Which substance is the oxidizing agent in the following reaction?
Fe2S3 + 12HNO3 → 2Fe(NO3)3 + 3S + 6NO2 + 6H2O
A) HNO3
B) S
C) NO2
D) Fe2S3
E) H2O
14) What is the coefficient of the permanganate ion when the following equation is balanced?
MnO4- + Br- → Mn2+ + Br2 (acidic solution)
A) 1
B) 2
C) 3
D) 5
E) 4
15) What is the coefficient of the dichromate ion when the following equation is balanced?
Fe2+ + Cr2O72- → Fe3+ + Cr3+ (acidic solution)
A) 1
B) 2
C) 3
D) 5
E) 6
16) What is the coefficient of Fe3+ when the following equation is balanced?
CN- + Fe3+ → CNO- + Fe2+ (basic solution)
A) 1
B) 2
C) 3
D) 4
E) 5
17) Which transformation could take place at the anode of an electrochemical cell?
A) Cr2O72- → Cr2+
B) F2 to F-
C) O2 to H2O
D) HAsO2 to As
E) None of the above could take place at the anode.
18) The purpose of the salt bridge in an electrochemical cell is to __________.
A) maintain electrical neutrality in the half-cells via migration of ions.
B) provide a source of ions to react at the anode and cathode.
C) provide oxygen to facilitate oxidation at the anode.
D) provide a means for electrons to travel from the anode to the cathode.
E) provide a means for electrons to travel from the cathode to the anode.
19) Which transformation could take place at the anode of an electrochemical cell?
A) NO → NO3-
B) CO2 → Cr2O42-
C) VO2+ → VO2+
D) H2AsO4 → H3AsO3
E) O2 → H2O2
20) Which transformation could take place at the cathode of an electrochemical cell?
A) MnO2 → MnO4-
B) Br2 → BrO3-
C) NO → HNO2
D) HSO4- → H2SO3
E) Mn2+ → MnO4-
Table 20.1
Half Reaction E°(V)
F2 (g) + 2e- → 2F- (aq) +2.87
Cl2 (g) + 2e- → 2Cl- (aq) +1.359
Br2 (l) + 2e- → 2Br- (aq) +1.065
O2 (g) + 4H+ (aq) + 4e- → 2H2O (l) +1.23
Ag+ + e- → Ag (s) +0.799
Fe3+ (aq) + e- → Fe2+ (aq) +0.771
I2 (s) + 2e- → 2I- (aq) +0.536
Cu2+ + 2e- → Cu (s) +0.34
2H+ + 2e- → H2 (g) 0
Pb2+ + 2e- → Pb (s) -0.126
Ni2+ + 2e- → Ni (s) -0.28
Li+ + e- → Li (s) -3.05
21) Which of the halogens in Table 20.1 is the strongest oxidizing agent?
A) Cl2
B) Br2
C) F2
D) I2
E) All of the halogens have equal strength as oxidizing agents.
22) Which one of the following types of elements is most likely to be a good oxidizing agent?
A) alkali metals
B) lanthanides
C) alkaline earth elements
D) transition elements
E) halogens
23) Which one of the following is the best oxidizing agent?
A) H2
B) Na
C) O2
D) Li
E) Ca
Table 20.2
24) Which of the following reactions will occur spontaneously as written?
A) Sn4+ (aq) + Fe3+ (aq) → Sn2+ (aq) + Fe2+ (aq)
B) 3Fe (s) + 2Cr3+ (aq) → 2Cr (s) + 3Fe2+ (aq)
C) Sn4+ (aq) + Fe2+ (aq) → Sn2+ (aq) + Fe (s)
D) 3Sn4+ (aq) + 2Cr (s) → 2Cr3+ (aq) + 3Sn2+ (aq)
E) 3Fe2+ (aq) → Fe (s) + 2Fe3+ (aq)
25) Which of the following reactions will occur spontaneously as written?
A) 3Fe2+ (aq) + Cr3+ (aq) → Cr (s) + 3Fe3+ (aq)
B) 2Cr3+ (aq) + 3Sn2+ (aq) → 3Sn4+ (aq) + 2Cr (s)
C) Sn4+ (aq) + Fe2+ (s) → Sn2+ (aq) + Fe (s)
D) Sn2+ (aq) + Fe2+ (s) → Sn4+ (aq) + Fe3+ (aq)
E) 2Cr (s) + 3Fe2+ (s) → 3Fe (s) + 2Cr3+ (aq)
26) 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?
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
E) Any of the above will change the measure cell potential.
27) 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?
A) lowering the pH in the cathode compartment
B) addition of more tin metal to the anode compartment
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.
28) What is the anode in an alkaline battery?
A) MnO2
B) KOH
C) Zn powder
D) Mn2O3
E) Pt
29) What is the cathode in an alkaline battery?
A) MnO2
B) KOH
C) Zn powder
D) Mn2O3
E) Pt
30) What is the cathode in the hydrogen fuel cell?
A) O2
B) KOH
C) Li
D) H2
E) Pt
31) In a lead-acid battery, the electrodes are consumed. In this battery,
A) the anode is Pb.
B) the anode is PbSO4.
C) the anode is PbO2.
D) the cathode is PbSO4.
E) the cathode is Pb.
32) Cathodic protection of a metal pipe against corrosion usually entails
A) attaching an active metal to make the pipe the anode in an electrochemical cell.
B) coating the pipe with another metal whose standard reduction potential is less negative than that of the pipe.
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.
E) coating the pipe with a fluoropolymer to act as a source of fluoride ion (since the latter is so hard to oxidize).
33) One of the differences between a voltaic cell and an electrolytic cell is that in an electrolytic cell __________.
A) an electric current is produced by a chemical reaction
B) electrons flow toward the anode
C) a nonspontaneous reaction is forced to occur
D) O2 gas is produced at the cathode
E) oxidation occurs at the cathode
20.2 Bimodal Questions
1) The gain of electrons by an element is called __________.
A) reduction
B) oxidation
C) disproportionation
D) fractionation
E) sublimation
2) __________ is reduced in the following reaction:
Cr2O72- + 6S2O32- + 14H+ → 2Cr3+ + 3S4O62- + 7H2O
A) Cr6+
B) S2+
C) H+
D) O2-
E) S4O62-
3) __________ is oxidized in the following reaction:
Cr2O72- + 6S2O32- + 14H+ → 2Cr3+ + 3S4O62- + 7H2O
A) Cr6+
B) S2+
C) H+
D) O2-
E) S4O62-
4) __________ is the oxidizing agent in the reaction below.
Cr2O72- + 6S2O32- + 14H+ → 2Cr3+ + 3S4O62- + 7H2O
A) Cr2O72-
B) S2O32-
C) H+
D) Cr3+
E) S4O62-
5) __________ is the reducing agent in the reaction below.
Cr2O72- + 6S2O32- + 14H+ → 2Cr3+ + 3S4O62- + 7H2O
A) Cr2O72-
B) S2O32-
C) H+
D) Cr3+
E) S4O62-
6) Which substance is serving as the reducing agent in the following reaction?
14H+ + Cr2O72- + 3Ni → 3Ni2+ + 2Cr3+ + 7H2O
A) Ni
B) H+
C) Cr2O72-
D) H2O
E) Ni2+
7) Which substance is serving as the oxidizing agent in the following reaction?
14H+ + Cr2O72- + 3Ni → 3Ni2+ + 2Cr3+ + 7H2O
A) Ni
B) H+
C) Cr2O72-
D) H2O
E) Ni2+
8) Which substance is the reducing agent in the reaction below?
Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2O
A) Pb
B) H2SO4
C) PbO2
D) PbSO4
E) H2O
9) Which substance is the oxidizing agent in the reaction below?
Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2O
A) Pb
B) H2SO4
C) PbO2
D) PbSO4
E) H2O
10) What is the oxidation number of chromium in Cr2O ion?
A) +3
B) +12
C) +7
D) +6
E) +14
11) What is the oxidation number of potassium in KMnO4?
A) 0
B) +1
C) +2
D) -1
E) +3
12) What is the oxidation number of manganese in the MnO ion?
A) +1
B) +2
C) +5
D) +4
E) +7
13) What is the oxidation number of manganese in MnO2?
A) +3
B) +2
C) +1
D) +4
E) +7
14) What is the oxidation number of oxygen in H2O2?
A) -1
B) -2
C) +1
D) +2
E) -1/2
15) __________ electrons appear in the following half-reaction when it is balanced.
S4O62- → S2O32-
A) 6
B) 2
C) 4
D) 1
E) 3
16) The balanced half-reaction in which chlorine gas is reduced to the aqueous chloride ion is a __________ process.
A) one-electron
B) two-electron
C) four-electron
D) three-electron
E) six-electron
17) The balanced half-reaction in which dichromate ion is reduced to chromium metal is a __________ process.
A) two-electron
B) six-electron
C) three-electron
D) four-electron
E) twelve-electron
18) The balanced half-reaction in which dichromate ion is reduced to chromium(III) ion is a __________ process.
A) four-electron
B) twelve-electron
C) three-electron
D) six-electron
E) two-electron
19) The balanced half-reaction in which sulfate ion is reduced to sulfite ion is a __________ process.
A) four-electron
B) one-electron
C) two-electron
D) three-electron
E) six-electron
20) The electrode at which oxidation occurs is called the __________.
A) oxidizing agent
B) cathode
C) reducing agent
D) anode
E) voltaic cell
21) The half-reaction occurring at the anode in the balanced reaction shown below is __________.
3MnO4- (aq) + 24H+ (aq) + 5Fe (s) → 3Mn2+ (aq) + 5Fe3+ (aq) + 12H2O (l)
A) MnO4- (aq) + 8H+ (aq) + 5e- → Mn2+ (aq) + 4H2O (l)
B) 2MnO4- (aq) + 12H+ (aq) + 6e- → 2Mn2+ (aq) + 3H2O (l)
C) Fe (s) → Fe3+ (aq) + 3e-
D) Fe (s) → Fe2+ (aq) + 2e-
E) Fe2+ (aq) → Fe3+ (aq) + e-
22) The half-reaction occurring at the cathode in the balanced reaction shown below is __________.
3MnO4- (aq) + 24H+ (aq) + 5Fe (s) → 3Mn2+ (aq) + 5Fe3+ (aq) + 12H2O (l)
A) MnO4- (aq) + 8H+ (aq) + 5e- → Mn2+ (aq) + 4H2O (l)
B) 2MnO4- (aq) + 12H+ (aq) + 6e- → 2Mn2+ (aq) + 3H2O (l)
C) Fe (s) → Fe3+ (aq) + 3e-
D) Fe (s) → Fe2+ (aq) + 2e-
E) Fe2+ (aq) → Fe3+ (aq) + e-
23) In a voltaic cell, electrons flow from the __________ to the __________.
A) salt bride, anode
B) anode, salt bridge
C) cathode, anode
D) salt bridge, cathode
E) anode, cathode
24) The reduction half reaction occurring in the standard hydrogen electrode is __________.
A) H2 (g, 1 atm) → 2H+ (aq, 1M) + 2e-
B) 2H+ (aq) + 2OH- → H2O (l)
C) O2 (g) + 4H+ (aq) + 4e- → 2H2O (l)
D) 2H+ (aq, 1M) + 2e- → H2 (g, 1 atm)
E) 2H+ (aq, 1M) + Cl2 (aq) → 2HCl (aq)
25) 1V = __________.
A) 1 amp ∙ s
B) 1 J/s
C) 96485 C
D) 1 J/C
E) 1 C/J
26) The more __________ the value of E°red, the greater the driving force for reduction.
A) positive
B) negative
C) exothermic
D) endothermic
E) extensive
Table 20.2
27) 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)
A) +0.46
B) +0.617
C) +1.39
D) -0.46
E) +1.21
28) 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)
A) -1.45
B) +2.99
C) +1.51
D) +3.05
E) +1.57
29) The standard cell potential (E°cell) for the voltaic cell based on the reaction below is __________ V.
2Cr (s) + 3Fe2+ (aq) → 3Fe (s) + 2Cr3+ (aq)
A) +0.30
B) +2.80
C) +3.10
D) +0.83
E) -0.16
30) The standard cell potential (E°cell) for the voltaic cell based on the reaction below is __________ V.
3Sn4+ (aq) + 2Cr (s) → 2Cr3+ (aq) + 3Sn2+ (aq)
A) +1.94
B) +0.89
C) +2.53
D) -0.59
E) -1.02
31) The relationship between the change in Gibbs free energy and the emf of an electrochemical cell is given by __________.
A) ΔG =
B) ΔG =
C) ΔG = -nFE
D) ΔG = -nRTF
E) ΔG =
32) 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)
A) -24.3
B) +24.3
C) -12.6
D) +12.6
E) -50.8
33) The standard cell potential (E°cell) of the reaction below is -0.55 V. The value of ΔG° for the reaction is __________ J/mol.
I2 (s) + 2Br- (aq) → 2I- (aq) + Br2 (l)
A) 0.54
B) 0.55
C) 5.5 × 10-6
D) 1.1 × 105
E) none of the above
34) 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)
A) -0.34
B) +66
C) -130
D) +130
E) none of the above
35) 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)
A) -24.3
B) +259
C) -259
D) +776
E) none of the above
36) The lead-containing reactant(s) consumed during recharging of a lead-acid battery is/are __________.
A) Pb (s) only
B) PbO2 (s) only
C) PbSO4 (s) only
D) both PbO2 (s) and PbSO4 (s)
E) both Pb (s) and PbO2 (s)
37) Galvanized iron is iron coated with __________.
A) magnesium.
B) zinc.
C) chromium.
D) phosphate.
E) iron oxide.
38) Corrosion of iron is retarded by __________.
A) the presence of salts
B) high pH conditions
C) low pH conditions
D) both the presence of salts and high pH conditions
E) both the presence of salts and low pH conditions
20.3 Algorithmic Questions
1) 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.
A) 2.0 × 10-2
B) 4.2 × 10-4
C) 1.4 × 10-1
D) 4.9 × 101
E) 1.0 × 10-12
2) 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.
A) 0.212
B) 0.118
C) 0.00222
D) 22.2
E) 0.232
3) 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)
A) 0.50
B) 0.84
C) 0.39
D) 0.76
E) 0.63
4) The standard cell potential (E°cell) for the reaction below is +1.10 V. The cell potential for this reaction is __________ V when the concentration of [Cu2+] = 1.0 × 10-5 M and [Zn2+] = 3.5 M.
Zn (s) + Cu2+ (aq) → Cu (s) + Zn2+ (aq)
A) 1.42
B) 1.26
C) 0.94
D) 0.78
E) 1.10
5) A voltaic cell is constructed with two Zn2+-Zn electrodes, where the half-reaction is
Zn2+ + 2e- → Zn (s) E° = -0.763 V
The concentrations of zinc ion in the two compartments are 5.50 M and 1.11 × 10-2 M, respectively. The cell emf is __________ V.
A) -1.54 × 10-3
B) -378
C) 0.0798
D) 0.160
E) -0.761
6) 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.
A) 2.20
B) 2.32
C) 2.10
D) 2.39
E) 2.23
7) The standard emf for the cell using the overall cell reaction below is +0.48 V:
Zn (s) + Ni2+ (aq) → Zn2+ (aq) + Ni (s)
The emf generated by the cell when [Ni2+] = 2.50 M and [Zn2+] = 0.100 M is ________ V.
A) 0.40
B) 0.50
C) 0.52
D) 0.56
E) 0.44
8) How many kilowatt-hours of electricity are used to produce 3.00 kg of magnesium in the electrolysis of molten MgCl2 with an applied emf of 4.50 V?
A) 0.0336
B) 0.0298
C) 7.4
D) 29.8
E) 14.9
9) The most useful ore of aluminum is bauxite, in which Al is present as hydrated oxides,
Al2O3 × H2O. The number of kilowatt-hours of electricity required to produce 4.00 kg of aluminum from electrolysis of compounds from bauxite is __________ when the applied emf is 5.00 V.
A) 0.0168
B) 0.0596
C) 39.7
D) 19.9
E) 59.6
10) The town of Natrium, West Virginia, derives its name from the sodium produced in the electrolysis of molten sodium chloride (NaCl) mined from ancient salt deposits. The number of kilowatt-hours of electricity required to produce 4.60 kg of metallic sodium from the electrolysis of molten NaCl(s) is __________ when the applied emf is 4.50 V.
A) 24.1
B) 0.0414
C) 0.0241
D) 48.3
E) 12.1
11) The electrolysis of molten AlCl3 for 3.25 hr with an electrical current of 15.0 A produces __________ g of aluminum metal.
A) 147
B) 0.606
C) 4.55 × 10-3
D) 16.4
E) 49.1
12) How many seconds are required to produce 4.00 g of aluminum metal from the electrolysis of molten AlCl3 with an electrical current of 12.0 A?
A) 27.0
B) 9.00
C) 1.19 × 103
D) 2.90 × 105
E) 3.57 × 103
13) How many minutes will it take to plate out 2.19 g of chromium metal from a solution of Cr3+ using a current of 39.5 amps in an electrolyte cell?
A) 5.14
B) 309
C) 103
D) 1.17
E) 15.4
14) What current (in A) is required to plate out 1.22 g of nickel from a solution of Ni2+ in 2.5 hour?
A) 65.4
B) 1.60 × 103
C) 0.446
D) 12.9
E) 0.891
15) How many grams of Ca metal are produced by the electrolysis of molten CaBr2 using a current of 30.0 amp for 9.0 hours?
A) 20.2
B) 404
C) 0.0622
D) 202
E) 101
16) How many grams of Cu are obtained by passing a current of 12 A through a solution of CuSO4 for 30 minutes?
A) 0.016
B) 7.1
C) 14
D) 28
E) 3.6
17) How many seconds are required to produce 1.0 g of silver metal by the electrolysis of a AgNO3 solution using a current of 5.0 amps?
A) 4.5 × 103
B) 3.2 × 103
C) 180
D) 3.7 × 10-5
E) 360
18) How many grams of copper will be plated out by a current of 2.3 A applied for 30 minutes to a 0.50 M solution of copper(II) sulfate?
A) 1.4
B) 2.7
C) 1.8 × 10-2
D) 3.6 × 10-2
E) 0.019
19) How many minutes will it take to plate out 4.56 g of Ni metal from a solution of Ni+2 using a current of 55.5 amps in an electrolytic cell?
A) 2.25
B) 4.50
C) 4.55
D) 135
E) 270
20) How many minutes will it take to plate out 16.22 g of Al metal from a solution of Al+3 using a current of 13.8 amps in an electrolytic cell?
A) 56.0
B) 70.0
C) 162
D) 210.
E) 12600
20.4 Short Answer
1) The most difficult species to reduce and the poorest oxidizing agent is __________.
2) At constant temperature and pressure the Gibbs free energy value is a measure of the __________ of a process.
3) In the formula ΔG = -nFE, F is the __________.
4) The dependence of cell emf on concentration is expressed in the __________ equation.
5) The potential (E) to move K+ from the extracellular fluid to the intracellular fluid necessitates work. The sign for this potential is __________.
6) The anode of the alkaline battery is powdered zinc in a gel that contacts __________.
7) The major product of a hydrogen fuel cell is __________.
8) When iron is coated with a thin layer of zinc to protect against corrosion, the iron is said to be __________.
9) The quantity of charge passing a point in a circuit in one second when the current is one ampere is called a __________.
10) Calculate the number of grams of aluminum produced in 30.0 minutes by electrolysis of AlCl3 at a current of 12.0 A.
20.5 True/False Questions
1) The electrode where reduction occurs is called the anode.
2) In a voltaic cell electrons flow from the anode to the cathode.
3) When the cell potential is negative in a voltaic cell the cell reaction will not proceed spontaneously.
4) The standard reduction potential, E°red, is proportional to the stoichiometric coefficient.
5) The standard reduction potential of X is 1.23 V and that of Y is -0.44 V therefore X is oxidized by Y.
6) The lithium ion battery has more energy per unit mass than nickel-cadmium batteries.
7) Disadvantages of the methanol fuel cell compared to the hydrogen fuel cell are consumption of catalyst and the production of a less environmentally safe product.
8) 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.
9) A positive number for maximum useful work in a spontaneous process (voltaic cell) indicates that the cell will perform work on its surroundings.
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