Deck 16: Oxidation and Reduction

Question 1

Reduction is the gain of electrons.

Answer 1

True

Question 2

Fuel cells are based on the tendency of some elements to gain electrons from gasoline.

Answer 2

False

Question 3

Redox reactions must involve the gain or loss of oxygen atoms.

Answer 3

False

Question 4

The sum of the oxidation numbers of all atoms in K₂Cr₂O₇ equals zero.

Question 5

The reducing agent is reduced during the reaction.

Question 6

The reaction 2 NO₂ → N₂O₄ would not be considered a redox reaction.

Question 7

Given that the Activity Series shown below is accurate,then Li(s)+ K⁺(aq)→ Li⁺ (aq)+ K(s)is a spontaneous reaction.
Activity Series =

Question 8

Cars are being developed that run on hydrogen gas and the only emission is water.

Question 9

Oxidation can be defined as the gain of oxygen atoms by another element.

Question 10

Reactions involving the transfer of electrons are called redox reactions.

Question 11

The half-reaction 2 Br ^1- → Br₂ + 2 e^- is balanced with respect to mass but it is not balanced with respect to charge.

Question 12

The oxidation number of manganese in MnO₄^1- is +7.

Question 13

The oxidation number of a chlorine atom is -1.

Question 14

The oxidation number of sodium in NaI is +1.

Question 15

Oxidation and reduction cannot both occur in the same chemical reaction.

Question 16

Oxidation is the loss of electrons.

Question 17

Reduction can be defined as the gain of oxygen atoms by another element.

Question 18

The oxidizing agent is the substance being reduced.

Question 19

The oxidation number of sulfur in SO₃ is -6.

Question 20

Most acids dissolve metals by the oxidation of H⁺ ions to hydrogen gas.

Question 21

An electrolytic cell is a spontaneous redox reaction.

Question 22

The rusting of iron is an example of the process known as corrosion.

Question 23

A spontaneous redox reaction can be used to produce electrical current.

Question 24

An electrochemical cell is based on the coupling of a spontaneous redox reaction.

Question 25

A sacrificial electrode works by being reduced which prevents the metal from being oxidized.

Question 26

Oxidation occurs at the cathode.

Question 27

It can be shown that copper metal lies below H₂ on the activity series of metals.This means that copper will dissolve in hydrochloric acid.

Question 28

The cathode is the electrode at which reduction occurs.

Question 29

Gold metal is found at the bottom of the activity series of metals since it is the most difficult metal to oxidize.

Question 30

The driving force that causes electrons to flow through a wire is called current.

Question 31

Corrosion of metals may be prevented by keeping them dry at all times.

Question 32

Rusting of iron requires the presence of both oxygen and water.

Question 33

Alkaline batteries are used in automobiles.

Question 34

To achieve the largest battery voltage possible,the battery should be assembled from a metal high on the activity series list with a metal ion low on the activity series list.

Question 35

Electrical current can be used to drive a nonspontaneous redox reaction.

Question 36

Which fact about fuel cells is FALSE?

A)Fuel cell automobiles are powered by water and the only emission is hydrogen.
B)Fuel cells are based on the tendency of some elements to gain electrons from other elements.
C)Fuel cell automobiles are whisper quiet.
D)Fuel cell automobiles are environmentally friendly.
E)all of the above

Question 37

Electrolysis is used to recover many metals from their oxide ores.

Question 38

Flashlight batteries are called dry cells.

Question 39

Ca²⁺ (aq)+ 2Na (s)→ Ca (s)+ 2 Na⁺ (aq)is a spontaneous reaction.
Activity Series =

Question 40

A galvanic cell is a spontaneous electrochemical cell.

Question 41

In the following reaction,
Mg (s)+ Cu²⁺ (aq)→ Mg²⁺ (aq)+ Cu (s):

A)Mg is the reducing agent and Cu is the oxidizing agent.
B)Mg²⁺ is the reducing agent and Cu is the oxidizing agent.
C)Cu is the reducing agent and Mg²⁺ is the oxidizing agent.
D)Cu²⁺ is the reducing agent and Mg is the oxidizing agent.
E)Mg is the reducing agent and Cu²⁺ is the oxidizing agent.

Question 42

For the reaction Si (s)+ O₂ (g)→ SiO₂ (g),the reducing agent is

A)Si.
B)O₂.
C)SiO₂.
D)O.
E)none of the above

Question 43

Which of the following are typically TRUE of a reducing agent?
1.It causes reduction.
2.It gains electron(s).
3.It is the oxidized substance.

A)1 and 2 only
B)1 and 3 only
C)2 and 3 only
D)All of 1,2,and 3
E)Neither 1,2 or 3

Question 44

The reducing agent typically:

A)gains electrons.
B)always remains unchanged during a reaction.
C)is the oxidized substance.
D)is itself reduced.
E)none of the above

Question 45

What is the oxidation state of the underlined element in the compound: CO₂?

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

Question 46

Identify the substance being reduced in the following reaction: CH₄ + 2O₂ $\to$ CO₂ + 2H₂O.

A)CH₄
B)O₂
C)CO₂
D)H₂O
E)none of the above

Question 47

Identify the oxidizing agent in the following reaction: CH₄ + 2O₂ $\to$ CO₂ + 2H₂O.

A)CH₄
B)O₂
C)CO₂
D)H₂O
E)none of the above

Question 48

Identify the reducing agent in the following reaction: CH₄ + 2O₂ $\to$ CO₂ + 2H₂O.

A)CH₄
B)O₂
C)CO₂
D)H₂O
E)none of the above

Question 49

Oxidation typically involves:

A)the loss of electrons.
B)the loss of oxygen.
C)the gain of electrons.
D)the gain of water.
E)none of the above

Question 50

What is the oxidation state of the underlined element in the compound: H₂SO₄?

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

Question 51

Identify the substance being oxidized in the following reaction: CH₄ + 2O₂ $\to$ CO₂ + 2H₂O.

A)CH₄
B)O₂
C)CO₂
D)H₂O
E)none of the above

Question 52

What is the oxidation state of the underlined element in the reaction: NaHCO₃ + HCl $\to$ NaCl + CO₂ + H₂O

A)0
B)+1
C)-1
D)+2
E)-2

Question 53

What is the oxidation state of the underlined element in the reaction: NaHCO₃ + HCl $\to$ NaCl + CO₂ + H₂O

A)0
B)+1
C)-1
D)+2
E)-2

Question 54

Reduction typically involves:

A)the loss of electrons.
B)the gain of oxygen.
C)the gain of electrons.
D)the gain of water.
E)none of the above

Question 55

The oxidizing agent typically:

A)loses electrons.
B)gains oxygen.
C)is the reactant that is reduced.
D)is oxidized.
E)none of the above

Question 56

The oxidation number of Cr in Cr₂O₇^2- is

A)+2.
B)-2.
C)+7.
D)+6.
E)none of the above

Question 57

What is the oxidation state of the underlined element in the compound: H₂SO₄?

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

Question 58

Which of the following are typically TRUE of an oxidizing agent?
1.It causes oxidation.
2.It gains electron(s).
3.It is the reduced substance.

A)1 and 2 only
B)1 and 3 only
C)2 and 3 only
D)All of 1,2,and 3
E)Neither 1,2,or 3

Question 59

What is the oxidation state of the underlined element in the reaction: NaHCO₃ + HCl $\to$ NaCl + CO₂ + H₂O

A)0
B)+1
C)-1
D)+2
E)-2

Question 60

In the following reaction,
Zn (s)+ CuSO₄ (aq)→ ZnSO₄ (aq)+ Cu (s)

A)Zn is the reducing agent and CuSO₄ is the oxidizing agent.
B)CuSO₄ is the reducing agent and Zn is the oxidizing agent.
C)ZnSO₄ is the reducing agent and Cu is the oxidizing agent.
D)Cu²⁺ is the reducing agent and Zn²⁺ is the oxidizing agent.
E)none of the above

Question 61

Balance the following half reaction in base solution: H₂0 (l)→ H₂ (g)

A)2H₂O (l)+ 2 e^- → H₂ (g)+ 2 OH^- (aq)
B)2H₂O (l)→ 2H₂ (g)+ 2 e^- + O₂
C)2H₂O (l)→ H₂ (g)+ 2 H⁺ + 2e^-
D)H₂O (l)→ 2H⁺ + 2OH^-
E)2H₂O (l)→ H₂ (g)+ 2OH^- (aq)+ 5 e^-

Question 62

What is the oxidation state of nitrogen in N₂O₃?

A)0
B)+1
C)+2
D)+3
E)+6

Question 63

The oxidation state of Na in Na₂SO₄ is:

A)+1
B)+2
C)+4
D)-1
E)none of the above

Question 64

Which substance below would contain a nitrogen atom with the highest oxidation number of all those shown?

A)NH₄ ¹⁺
B)N₂
C)NO₂
D)NO₃ ^1-
E)NH₃

Question 65

Assign the oxidation state of each atom in potassium chlorate,KClO₃.

A)K = +1,Cl = +1,O = -2
B)K = -1,Cl = -1,O = +2
C)K = +1,Cl = +5,O = -2
D)K = +1,Cl = -1,O = 0
E)K = -1,Cl = +1,O = 0

Question 66

If you properly balance the following half reaction in base solution,how many electrons would appear on the product side of the equation? Al (s)→ Al(OH)₄^1- (aq)

A)2
B)3
C)4
D)5
E)none of the above

Question 67

From the activity list included in this problem,which element/ion is the most easily oxidized?
Activity Series =

A)Na
B)Ca
C)Na⁺
D)Li
E)Li+

Question 68

Reduction involves which of the following?
1.Loss of electron(s).
2.Gain of electron(s).
3.Decrease in oxidation state.

A)1 only
B)2 only
C)3 only
D)1 and 2 only
E)2 and 3 only

Question 69

What is the balanced oxidation half-reaction for the following unbalanced redox reaction?
Ca(s)+ Ag⁺(aq) $\to$ Ca²⁺(aq)+ Ag(s)

A)Ca → Ca²⁺ + 2 e^-
B)Ag⁺ → Ag + e^-
C)2 e^- + Ca → Ca²⁺
D)2 Ag⁺ + 2 e^-→ 2Ag
E)none of the above

Question 70

Balance the following half reaction in acid solution: MnO₄^- $\to$ Mn²⁺ (aq)

A)MnO₄^- → Mn²⁺ + 3 e^-
B)MnO₄^- + 8 H⁺→ Mn²⁺ + 4 H₂O
C)MnO₄^- + 8 H⁺→ Mn²⁺ + 4 H₂O +5 e^-
D)MnO₄^- + 8 H⁺ + 5 e^-→ Mn²⁺ + 4 H₂O
E)none of the above

Question 71

Assign the oxidation state of each atom in sodium sulfate,Na₂SO₄.

A)Na = +1,S = +4,O = -2
B)Na = +1,S = -2,O = +4
C)Na = +2,S = +6,O = -2
D)Na = +1,S = +6,O = -2
E)Na = +2,S = -2,O = 0

Question 72

If you properly balance the following half reaction in acid solution,how many electrons would appear on the product side of the equation? NO (g)→ NO₃^1- (aq)

A)1
B)2
C)3
D)5
E)none of the above

Question 73

What is the oxidation state of the underlined element in the reaction: Cl₂ + Mg $\to$ MgCl₂

A)0
B)+2
C)-2
D)+4
E)-4

Question 74

The oxidation state of Mn in KMnO₄ is:

A)+1
B)-1
C)+5
D)+7
E)none of the above

Question 75

What must be done to the following half-reactions before they can be added together?
Mn (s)→ Mn ²⁺(aq)+ 2e^-
Fe ³⁺ (aq)+ 3 e^- → Fe (s)

A)Double the Mn half-reaction.
B)Double the Mn half-reaction and triple the Fe half-reaction.
C)Triple the Mn half-reaction and double the Fe half-reaction.
D)Add H⁺ ions to the left-side of the Mn reaction.
E)none of the above

Question 76

What is the balanced reduction half-reaction for the following unbalanced redox reaction:
Ca(s)+ Ag⁺(aq) $\to$ Ca²⁺(aq)+ Ag(s)

A)Ca → Ca²⁺+ 2 e^-
B)Ag⁺ → Ag + 1 e^-
C)2 e^- + Ca → Ca²⁺
D)2Ag⁺ + 2 e^-→ 2Ag
E)none of the above

Question 77

Balance the redox reaction: Br^-(aq)+ Cr₂O₇^2-(aq) $\to$ Cr³⁺ + Br₂ (l)

A)4 Br^- + Cr₂O₇^2- + 7 H⁺ → 2 Cr³⁺ + 2 Br₂ + 7 H₂O
B)6 Br^- + Cr₂O₇^2- + 147 H⁺ → 2 Cr³⁺ + 3 Br₂ + 7 H₂O
C)2 Br^-+ Cr₂O₇^2- + 147 H⁺ → 2 Cr³⁺ + Br₂ + 7 H₂O
D)2 Br^- + 2 Cr₂O₇^2- + 147 H⁺ → 4 Cr³⁺+ Br₂ + 14 H₂O
E)none of the above

Question 78

What is the oxidation state of sulfur in SO₃^2-?

A)0
B)-2
C)+3
D)+4
E)+6

Question 79

Oxidation involves which of the following?
1.Loss of electron(s).
2.Gain of electron(s).
3.Increase in oxidation state.

A)1 only
B)2 only
C)3 only
D)1 and 3 only
E)2 and 3 only

Question 80

What is the balanced oxidation half-reaction for the following unbalanced redox reaction:
Ca(s)+ Ag⁺(aq) $\to$ Ca²⁺(aq)+ Ag(s)

A)Ca → Ca²⁺ + 2 e^-
B)Ag⁺ → Ag + e^-
C)2 e^- + Ca → Ca²⁺
D)2 Ag⁺ + 2 e^-→ 2Ag
E)none of the above