Chapter 17 - Electrochemistry

Question 1

Question

What is the oxidation number of bromine in the BrO3- ion?

Answer

A) -1
B) +1
C) +3
D) +5
E) +7

Question 2

Question

What is the oxidation number of sulfur in the HSO4- ion?

Answer

A) -2
B) +1
C) +2
D) +4
E) +6

Question 3

Question

Which element is oxidized in the reaction below? Fe(CO)5 (l) + 2HI (g) → Fe(CO)4I2 (s) + CO (g) + H2 (g)

Answer

A) Fe
B) C
C) O
D) H
E) I

Question 4

Question

Which element is reduced in the reaction below? Fe(CO)5 (l) + 2HI (g) → Fe(CO)4I2 (s) + CO (g) + H2 (g)

Answer

A) Fe
B) C
C) O
D) H
E) I

Question 5

Question

Which of the following reactions is a redox reaction? (a) K2CrO4 + BaCl2 → BaCrO4 + 2KCl (b) Pb22+ + 2Br- → PbBr (c) Cu + S → CuS

Answer

A) (a) only
B) (b) only
C) (c) only
D) (a) and (c)
E) (b) and (c)

Question 6

Question

Which one of the following reactions is a redox reaction?

Answer

A) NaOH + HCl → NaCl + H2O
B) Pb2+ + 2Cl- → PbCl2
C) AgNO3 + HCl → HNO3 + AgCl
D) None of the above is a redox reaction.

Question 7

Question

Which substance is the reducing agent in the following reaction? Fe2S3 + 12HNO3 → 2Fe(NO3)3 + 3S + 6NO2 + 6H2O

Answer

A) HNO3
B) S
C) NO2
D) Fe2S3
E) H2O

Question 8

Question

What is the coefficient of the permanganate ion when the following equation is balanced? MnO4- + Br- → Mn2+ + Br2 (acidic solution)

Answer

A) 1
B) 2
C) 3
D) 5
E) 4

Question 9

Question

What is the coefficient of Fe3+ when the following equation is balanced? CN- + Fe3+ → CNO- + Fe2+ (basic solution)

Answer

A) 1
B) 2
C) 3
D) 4
E) 5

Question 10

Question

The purpose of the salt bridge in an electrochemical cell is to __________.

Answer

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.

Question 11

Question

Which transformation could take place at the anode of an electrochemical cell?

Answer

A) NO → NO3-
B) CO2 → Cr2O42-
C) VO2+ → VO2+
D) H2AsO4 → H3AsO3
E) O2 → H2O2

Question 12

Question

Which transformation could take place at the cathode of an electrochemical cell?

Answer

A) MnO2 → MnO4-
B) Br2 → BrO3-
C) NO → HNO2
D) HSO4- → H2SO3
E) Mn2+ → MnO4-

Question 13

Question

Which of the halogens in Table 20.1 is the strongest oxidizing agent?

Image:

5c98fd0f-9a8b-4369-8591-5365eef33a99 (image/png)

Answer

A) Cl2
B) Br2
C) F2
D) I2
E) All of the halogens have equal strength as oxidizing agents.

Question 14

Question

Which one of the following types of elements is most likely to be a good oxidizing agent?

Answer

A) alkali metals
B) lanthanides
C) alkaline earth elements
D) transition elements
E) halogens

Question 15

Question

Which one of the following is the best oxidizing agent?

Answer

A) H2
B) Na
C) O2
D) Li
E) Ca

Question 16

Question

Which of the following reactions will occur spontaneously as written?

Answer

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) ← I chose this one
D) 3Sn4+ (aq) + 2Cr (s) → 2Cr3+ (aq) + 3Sn2+ (aq)
E) 3Fe2+ (aq) → Fe (s) + 2Fe3+ (aq)

Question 17

Question

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?

Answer

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.

Question 18

Question

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?

Answer

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.

Question 19

Question

Cathodic protection of a metal pipe against corrosion usually entails

Answer

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).

Question 20

Question

One of the differences between a voltaic cell and an electrolytic cell is that in an electrolytic cell __________.

Answer

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

Question 21

Question

__________ is reduced in the following reaction: Cr2O72- + 6S2O32- + 14H+ → 2Cr3+ + 3S4O62- + 7H2O

Answer

A) Cr6+
B) S2+
C) H+
D) O2-
E) S4O62-

Question 22

Question

Which substance is serving as the oxidizing agent in the following reaction? 14H+ + Cr2O72- + 3Ni → 3Ni2+ + 2Cr3+ + 7H2O

Answer

A) Ni
B) H+
C) Cr2O72-
D) H2O
E) Ni2+

Question 23

Question

__________ electrons appear in the following half-reaction when it is balanced. S4O62- → S2O32-

Answer

A) 6
B) 2
C) 4
D) 1
E) 3

Question 24

Question

The balanced half-reaction in which dichromate ion is reduced to chromium metal is a __________ process.

Answer

A) two-electron
B) six-electron
C) three-electron
D) four-electron
E) twelve-electron

Question 25

Question

The electrode at which oxidation occurs is called the __________.

Answer

A) oxidizing agent
B) cathode
C) reducing agent
D) anode
E) voltaic cell

Question 26

Question

In a voltaic cell, electrons flow from the __________ to the __________.

Answer

A) salt bride, anode
B) anode, salt bridge
C) cathode, anode
D) salt bridge, cathode
E) anode, cathode

Question 27

Question

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)

Image:

554089bc-c30c-4215-993a-505ea84df075 (image/png)

Answer

A) +0.46
B) +0.617
C) +1.39
D) -0.46
E) +1.21

Question 28

Question

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)

Image:

26c1b370-c5d4-47b5-95ba-ad20bca73ad2 (image/png)

Answer

A) -1.45
B) +2.99
C) +1.51
D) +3.05
E) +1.57

Question 29

Question

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)

Answer

A) -24.3
B) +24.3
C) -12.6
D) +12.6
E) -50.8

Question 30

Question

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)

Answer

A) -0.34
B) +66
C) -130
D) +130
E) none of the above

Question 31

Question

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)

Answer

A) -24.3
B) +259
C) -259
D) +776
E) none of the above

Question 32

Question

Galvanized iron is iron coated with __________.

Answer

A) magnesium.
B) zinc.
C) chromium.
D) phosphate.
E) iron oxide.

Question 33

Question

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.

Answer

A) 2.0 × 10-2
B) 4.2 × 10-4
C) 1.4 × 10-1
D) 4.9 × 101
E) 1.0 × 10-12

Question 34

Question

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.

Answer

A) 0.212
B) 0.118
C) 0.00222
D) 22.2
E) 0.232

Question 35

Question

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)

Answer

A) 0.50
B) 0.84
C) 0.39
D) 0.76
E) 0.63

Question 36

Question

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.

Answer

A) 2.20
B) 2.32
C) 2.10
D) 2.39
E) 2.23

Question 37

Question

The most difficult species to reduce and the poorest oxidizing agent is __________.

Answer

A) Fr+
B) F-
C) Li+
D) He

Question 38

Question

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.

Answer

True
False

	Created by Dawn G almost 8 years ago

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Chapter 17 - Electrochemistry

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