Deck 14: Oxidation-Reduction Reactions

Question 1

What is the oxidation number of sulfur in the thiosulfate ion, S₂O₃^2-?

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

Answer 1

+2

Question 2

What is the oxidation number of sulfur in sulfur trioxide, SO₃?

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

Answer 2

+6

Question 3

Which statement is TRUE?

A) Hydrogen atom to hydrogen ion (H⁺) is reduction.
B) Oxygen atom to oxide ion (O^2-) is reduction.
C) Tin atom to tin(IV) ion is reduction.
D) Fluoride ion (F^-) to fluorine atom is reduction.

Answer 3

Oxygen atom to oxide ion (O^2-) is reduction.

Question 4

In the context of chemical reactions, oxidation refers to the:

A) gain of electrons.
B) loss of electrons.
C) loss of oxygen.
D) loss of water.

Question 5

Given the accompanying partial activity series, which element(s) can reduce zinc ion to elemental zinc?
Zn $\rightarrow$ Zn²⁺ + 2e^-
Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) nickel
B) iron
C) copper
D) nickel, iron, and copper
E) None of these elements can reduce zinc ion to elemental zinc.

Question 6

The major credit for creating the first "battery" goes to:

A) James Watt.
B) Andre Ampere.
C) Alessandro Volta.
D) Georg Ohm.

Question 7

Given the accompanying partial activity series, predict which element or ion will react with cobalt, Co.
Zn $\rightarrow$ Zn²⁺ + 2e^-
Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) Zn
B) Fe²⁺
C) Ni
D) Cu²⁺

Question 8

Given the accompanying partial activity series, predict which element or ion will react with the cobalt ion, Co²⁺.
Zn $\rightarrow$ Zn²⁺ + 2e^-
Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) Zn
B) Fe²⁺
C) Ni
D) Cu²⁺

Question 9

Considering the following net ionic equation: Mg + Fe²⁺ $\rightarrow$ Mg²⁺ + Fe
The species REDUCED is _____, and the REDUCING AGENT is _____.

A) Mg; Mg
B) Mg; Fe²⁺
C) Fe²⁺; Fe²⁺
D) Fe²⁺; Mg

Question 10

What is the oxidation number of carbon in carbon dioxide, CO₂?

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

Question 11

Which statement is FALSE?

A) Silver ion (Ag⁺) to silver atom is reduction.
B) Chloride (Cl^-) ion to chlorine atom is reduction.
C) Hydrogen atom to hydride ion (H^-) is reduction.
D) Sulfur atom to sulfide ion (S^2-) is reduction.

Question 12

What is the oxidation number of sulfur in the sulfite ion, SO₃^2-?

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

Question 13

Given the accompanying partial activity series, predict which reaction(s) will occur as written.
Zn $\rightarrow$ Zn²⁺ + 2e^-
Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) Zn + Fe²⁺ $\rightarrow$ Zn²⁺ + Fe
B) Fe + Ni²⁺ $\rightarrow$ Fe²⁺ + Ni
C) Co + Cu²⁺ $\rightarrow$ Cu + Co²⁺
D) Zn + Fe²⁺ $\rightarrow$ Zn²⁺ + Fe, Fe + Ni²⁺ $\rightarrow$ Fe²⁺ + Ni , and Co + Cu²⁺ $\rightarrow$ Cu + Co²⁺
E) None of these reactions will occur as written.

Question 14

In the context of chemical reactions, reduction refers to the:

A) gain of electrons.
B) loss of electrons.
C) gain of oxygen.
D) loss of water.

Question 15

What is the oxidation number of carbon in carbon monoxide, CO?

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

Question 16

What is the oxidation number of nitrogen in the nitrate ion, NO₃^-?

A) -1
B) -3
C) +6
D) +5

Question 17

Given the accompanying partial activity series, which element CANNOT reduce nickel(II) to elemental nickel?
Zn $\rightarrow$ Zn²⁺ + 2e^-
Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) zinc
B) iron
C) cobalt
D) copper

Question 18

Which example illustrates a redox reaction?

A) metal and nonmetal
B) double displacement
C) neutralization
D) precipitation

Question 19

Considering the following net ionic equation: Mg + Fe²⁺ $\rightarrow$ Mg²⁺ + Fe
The species that is OXIDIZED is _____, and the OXIDIZING AGENT is _____.

A) Mg; Mg
B) Mg; Fe²⁺
C) Fe²⁺; Fe²⁺
D) Fe²⁺; Mg

Question 20

Which example does NOT illustrate a redox reaction?

A) metal and nonmetal
B) double displacement
C) single displacement
D) combustion

Question 21

Which example BEST represents the reaction between copper and hydrochloric acid?

A) Cu + 2 HCl $\rightarrow$ CuCl₂ + H₂
B) Cu + 2 HCl $\rightarrow$ CuH₂ + Cl₂
C) Cu + H₂Cl $\rightarrow$ CuCl + H₂
D) Copper and hydrochloric acid do not react.

Question 22

Which example represents the reduction half-reaction for cobalt/cobalt(II)?

A) Co $\rightarrow$ Co²⁺ + 2 e^-
B) Co + 2 e^- $\rightarrow$ Co^2-
C) Co²⁺ + 2 e^- $\rightarrow$ Co
D) Co²⁺ $\rightarrow$ Co + 2 e^-

Question 23

What are the coefficients of the balanced equation that represents the reaction in a magnesium/aluminum electrochemical cell?
Mg (s) + Al³⁺ (aq) $\rightarrow$ Al (s) + Mg²⁺ (aq)

A) 1, 1, 1, 1
B) 3, 2, 2, 3
C) 2, 3, 3, 2
D) 1, 2, 1, 3

Question 24

Given the accompanying partial activity series, which element(s) will NOT react with acid?
Zn $\rightarrow$ Zn²⁺ + 2e^-
Fe $\rightarrow$ Fe²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
H₂ $\rightarrow$ 2H⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-
Ag $\rightarrow$ Ag⁺ + e^-

A) nickel
B) iron
C) silver
D) nickel, iron, and silver
E) All of these elements will react with acid.

Question 25

Consider an electrochemical cell consisting of zinc and cobalt half-cells. Use the partial activity series included to determine the direction in which the electrons in the wire will flow.
Zn $\rightarrow$ Zn²⁺ + 2e^-
Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) from the zinc anode to the cobalt cathode
B) from the zinc cathode to the cobalt anode
C) from the cobalt anode to the zinc cathode
D) from the cobalt cathode to the zinc anode

Question 26

The reduction half-reaction for the reaction of zinc with hydrochloric acid is:

A) Zn²⁺ + 2 e^- $\rightarrow$ Zn.
B) Zn $\rightarrow$ Zn²⁺ + 2 e^-.
C) H₂ $\rightarrow$ 2 H⁺ + 2 e^-.
D) 2 H⁺ + 2 e^- $\rightarrow$ H₂.

Question 27

Given the accompanying partial activity series, which element(s) will react with acid?
Zn $\rightarrow$ Zn²⁺ + 2e^-
Fe $\rightarrow$ Fe²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
H₂ $\rightarrow$ 2H⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-
Ag $\rightarrow$ Ag⁺ + e^-

A) nickel
B) copper
C) silver
D) nickel, copper, and silver
E) None of these elements will react with acid.

Question 28

If the accompanying drawing of an electrochemical cell represents an iron-nickel cell, use the partial activity series included to describe the component labeled 2. Zn $\rightarrow$ Zn²⁺ + 2e^- Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) iron anode
B) nickel anode
C) iron cathode
D) nickel cathode

Question 29

If the accompanying drawing of an electrochemical cell represents an iron-nickel cell, use the partial activity series included to select the half-reaction represented by the RIGHT side of the cell. Zn $\rightarrow$ Zn²⁺ + 2e^- Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) Fe $\rightarrow$ Fe²⁺ + 2e^-
B) Ni $\rightarrow$ Ni²⁺ + 2e^-
C) Fe²⁺ + 2e^- $\rightarrow$ Fe
D) Ni²⁺ + 2e^- $\rightarrow$ Ni

Question 30

Which example BEST represents the reaction between magnesium and hydrochloric acid?

A) Mg + 2 HCl $\rightarrow$ MgCl₂ + H₂
B) Mg + 2 HCl $\rightarrow$ MgH₂ + Cl₂
C) Mg + H₂Cl $\rightarrow$ MgCl + H₂
D) Magnesium and hydrochloric acid do not react.

Question 31

Using the accompanying drawing of an electrochemical cell, identify the components labeled 1, 2, and 5, respectively.

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

Question 32

Consider an electrochemical cell consisting of zinc and nickel half-cells. Use the partial activity series included to determine the direction in which the electrons in the wire will flow.
Zn $\rightarrow$ Zn²⁺ + 2e^-
Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) from the zinc anode to the nickel cathode
B) from the zinc cathode to the nickel anode
C) from the nickel anode to the zinc cathode
D) from the nickel cathode to the zinc anode

Question 33

Given the accompanying partial activity series, which element(s) can reduce copper(II) to elemental copper?
Zn $\rightarrow$ Zn²⁺ + 2e^-
Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) nickel
B) iron
C) zinc
D) nickel, iron, and zinc
E) None of these elements can reduce copper(II) to elemental copper.

Question 34

Which example represents the oxidation half-reaction for cobalt/cobalt(II)?

A) Co $\rightarrow$ Co²⁺ + 2 e^-
B) Co + 2 e^- $\rightarrow$ Co^2-
C) Co²⁺ + 2 e^- $\rightarrow$ Co
D) Co²⁺ $\rightarrow$ Co + 2 e^-

Question 35

If the accompanying drawing of an electrochemical cell represents an iron-nickel cell, use the partial activity series included to select the half-reaction represented by the LEFT side of the cell. Zn $\rightarrow$ Zn²⁺ + 2e^- Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) Fe $\rightarrow$ Fe²⁺ + 2e^-
B) Ni $\rightarrow$ Ni²⁺ + 2e^-
C) Fe²⁺ + 2e^- $\rightarrow$ Fe
D) Ni²⁺ + 2e^- $\rightarrow$ Ni

Question 36

Given the accompanying partial activity series, which element(s) will react with acid?
Zn $\rightarrow$ Zn²⁺ + 2e^-
Fe $\rightarrow$ Fe²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
H₂ $\rightarrow$ 2H⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-
Ag $\rightarrow$ Ag⁺ + e^-

A) iron
B) nickel
C) zinc
D) iron, nickel, and zinc
E) None of these elements will react with acid.

Question 37

If the accompanying drawing of an electrochemical cell represents an iron-nickel cell, use the partial activity series included to identify the components labeled 1, 2, 3, and 4 respectively. Zn $\rightarrow$ Zn²⁺ + 2e^- Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) iron, nickel, iron ion solution, nickel ion solution
B) nickel, iron, iron ion solution, nickel ion solution
C) nickel, iron, nickel ion solution, iron ion solution
D) iron, nickel, nickel ion solution, iron ion solution

Question 38

The oxidation half-reaction for the reaction of zinc with hydrochloric acid is:

A) Zn²⁺ + 2 e^- $\rightarrow$ Zn.
B) Zn $\rightarrow$ Zn²⁺ + 2 e^-.
C) H₂ $\rightarrow$ 2 H⁺ + 2 e^-.
D) 2 H⁺ + 2 e^- $\rightarrow$ H₂.

Question 39

Knowing that sodium and potassium react violently with water, predict which element will also react with water.

A) cesium
B) aluminum
C) zinc
D) It is impossible to predict accurately from the information given.

Question 40

If the accompanying drawing of an electrochemical cell represents an iron-nickel cell, use the partial activity series included to determine the component labeled 1. Zn $\rightarrow$ Zn²⁺ + 2e^- Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) iron anode
B) nickel anode
C) iron cathode
D) nickel cathode

Question 41

Write the balanced net ionic equation for the reaction consisting of the two half-reactions given.
Cu $\rightarrow$ Cu²⁺ + 2 e^-
Ag⁺ + e^- $\rightarrow$ Ag

A) Cu (s) + Ag⁺ (aq) $\rightarrow$ Cu²⁺ (aq) + Ag (s)
B) Cu (s) + 2 Ag⁺ (aq) $\rightarrow$ Cu²⁺ (aq) + 2 Ag (s)
C) Ag (s) + Cu²⁺ (aq) $\rightarrow$ Ag⁺ (aq) + Cu (s)
D) 2 Ag (s) + Cu²⁺ (aq) $\rightarrow$ 2 Ag⁺ (aq) + Cu (s)

Question 42

Write the balanced net ionic equation for the reaction consisting of the two half-reactions given. Mg $\rightarrow$ Mg²⁺ + 2 e^-
Pb⁴⁺ + 4 e^- $\rightarrow$ Pb

A) Pb (s) + Mg²⁺ (aq) $\rightarrow$ Pb⁴⁺ (aq) + Mg (s)
B) Mg (s) + Pb⁴⁺ (aq) $\rightarrow$ Pb (s) + Mg²⁺ (aq)
C) 2 Mg (s) + Pb⁴⁺ (aq) $\rightarrow$ Pb (s) + 2 Mg²⁺ (aq)
D) Pb (s) + 2 Mg²⁺ (aq) $\rightarrow$ Pb⁴⁺ (aq) + 2 Mg (s)

Question 43

Which pair of half-reactions takes place in a fuel cell?

A) reduction: O₂ + 4 H⁺ + 4 e^- $\rightarrow$ 2H₂O; oxidation: H₂ $\rightarrow$ 2 H⁺ + 2 e^-
B) reduction: H₂ $\rightarrow$ 2 H⁺ + 2 e^-; oxidation: O₂ + 4 H⁺ + 4 e^- $\rightarrow$ 2 H₂O
C) reduction: O₂ + 4 H⁺ + 4 e^- $\rightarrow$ 2H₂O; oxidation: 2 H⁺ + 2 e^- $\rightarrow$ H₂
D) reduction: H₂ $\rightarrow$ 2 H⁺ + 2 e^-; oxidation: 2 H₂O $\rightarrow$ O₂ + 4H⁺ + 4 e^-

Question 44

Which reaction could be used to electroplate nickel with gold?

A) Ni (s) + 2 Au⁺ (aq) $\rightarrow$ Ni²⁺ (aq) + 2 Au (s)
B) Zn (s) + 2 Au⁺ (aq) $\rightarrow$ Zn²⁺ (aq) + 2 Au (s)
C) 2 Au (s) + Ni²⁺ (aq) $\rightarrow$ Ni (s) + 2 Au⁺ (aq)
D) 2 Au (s) + Zn²⁺ (aq) $\rightarrow$ Zn (s) + 2 Au⁺ (aq)

Question 45

Use the partial activity series included to determine which reaction will NOT occur spontaneously. Zn $\rightarrow$ Zn²⁺ + 2e^-
Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) Fe (s) + Co²⁺ (aq) $\rightarrow$ Fe²⁺ (aq) + Co (s)
B) Zn (s) + Ni²⁺ (aq) $\rightarrow$ Zn²⁺ (aq) + Ni (s)
C) Cu (s) + Fe²⁺ (aq) $\rightarrow$ Cu²⁺ (aq) + Fe (s)
D) Ni (s) + Cu²⁺ (aq) $\rightarrow$ Ni²⁺ (aq) + Cu (s)

Question 46

Which pair of half-reactions could be used to electroplate silver onto iron?

A) reduction: Ag⁺ + e^- $\rightarrow$ Ag; oxidation: Ag $\rightarrow$ Ag⁺ + e^-
B) reduction: Ag $\rightarrow$ Ag⁺ + e^-; oxidation: Ag⁺ + e^- $\rightarrow$ Ag
C) reduction: Fe²⁺ + 2 e^- $\rightarrow$ Fe; oxidation: Fe $\rightarrow$ Fe²⁺ + 2 e^-
D) reduction: Fe $\rightarrow$ Fe²⁺ + 2 e^-; oxidation: Fe²⁺ + 2 e^- $\rightarrow$ Fe

Question 47

Use the partial activity series included to determine which reaction will NOT occur spontaneously. Zn $\rightarrow$ Zn²⁺ + 2e^-
Fe $\rightarrow$ Fe²⁺ + 2e^-
Co $\rightarrow$ Co²⁺ + 2e^-
Ni $\rightarrow$ Ni²⁺ + 2e^-
Cu $\rightarrow$ Cu²⁺ + 2e^-

A) Fe (s) + Co²⁺ (aq) $\rightarrow$ Fe²⁺ (aq) + Co (s)
B) Zn (s) + Ni²⁺ (aq) $\rightarrow$ Zn²⁺ (aq) + Ni (s)
C) Co (s) + Fe²⁺ (aq) $\rightarrow$ Co²⁺ (aq) + Fe (s)
D) Ni (s) + Cu²⁺ (aq) $\rightarrow$ Ni²⁺ (aq) + Cu (s)

Question 48

What are the coefficients of the balanced equation that represents the reaction in a magnesium/iron electrochemical cell?
Mg (s) + Fe²⁺ (aq) $\rightarrow$ Fe (s) + Mg²⁺ (aq)

A) 1, 1, 1, 1
B) 1, 2, 2, 1
C) 2, 1, 1, 2
D) 1, 2, 1, 2

Question 49

Write the balanced net ionic equation for the reaction consisting of the two half-reactions given.
Cu $\rightarrow$ Cu²⁺ + 2e^-
Au³⁺ + 3e^- $\rightarrow$ Au

A) Cu (s) + Au³⁺ (aq) $\rightarrow$ Cu²⁺ (aq) + Au (s)
B) 3 Cu (s) + 2 Au³⁺ (aq) $\rightarrow$ 3 Cu²⁺ (aq) + 2 Au (s)
C) 2 Au (s) + 3 Cu²⁺ (aq) $\rightarrow$ 2 Au³⁺ (aq) + 3 Cu (s)
D) Au (s) + Cu²⁺ (aq) $\rightarrow$ Au³⁺ (aq) + Cu (s)

Question 50

Given the following net ionic equation, select the correct pairing of half-reactions. Mg (s) + Zn²⁺ (aq) $\rightarrow$ Mg²⁺ (aq) + Zn (s)

A) reduction: Mg $\rightarrow$ Mg²⁺ + 2 e^-; oxidation: Zn²⁺ + 2 e^- $\rightarrow$ Zn
B) reduction: Zn²⁺ + 2 e^- $\rightarrow$ Zn; oxidation: Mg $\rightarrow$ Mg²⁺ + 2 e^-
C) reduction: Zn²⁺ + 2 e^- $\rightarrow$ Zn; oxidation: Mg²⁺ + 2 e^- $\rightarrow$ Mg
D) reduction: Zn $\rightarrow$ Zn²⁺ + 2 e^-; oxidation: Mg $\rightarrow$ Mg²⁺ + 2 e^-

Question 51

What are the coefficients of the balanced equation that represents the reaction in a magnesium/chromium electrochemical cell?
Mg (s) + Cr³⁺ (aq) $\rightarrow$ Cr (s) + Mg²⁺ (aq)

A) 1, 1, 1, 1
B) 3, 2, 2, 3
C) 2, 3, 3, 2
D) 1, 2, 1, 3

Question 52

Given the following net ionic equation, select the CORRECT pairing of half-reactions. 2 Al (s) + 3 Pb²⁺ (aq) $\rightarrow$ 2 Al³⁺ (aq) + 3 Pb (s)

A) reduction: Al $\rightarrow$ Al³⁺ + 3 e^-; oxidation: Pb²⁺ + 2 e^- $\rightarrow$ Pb
B) reduction: Pb²⁺ + 2 e^- $\rightarrow$ Pb; oxidation: Al $\rightarrow$ Al³⁺ + 3 e^-
C) reduction: Al³⁺ + 3 e^- $\rightarrow$ Al; oxidation: Pb²⁺ + 2 e^- $\rightarrow$ Pb
D) reduction: Pb $\rightarrow$ Pb²⁺ + 2 e^-; oxidation: Al $\rightarrow$ Al³⁺ + 3 e^-