Deck 16: Oxidation and Reduction

Question 1

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

Answer 1

True

Question 2

The oxidation number of sulfur in SO₃ is -6.

Answer 2

False

Question 3

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

Answer 3

True

Question 4

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

Question 5

The oxidation number of a chlorine atom is -1.

Question 6

The oxidizing agent is the substance being reduced.

Question 7

Reactions involving the transfer of electrons are called redox reactions.

Question 8

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

Question 9

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

Question 10

Reduction is the gain of electrons.

Question 11

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

Question 12

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

Question 13

In the reaction S + O₂ → SO₂ ,the O₂ is being oxidized.

Question 14

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 15

The substance being reduced is the oxidizing agent while the substance being oxidized is the reducing agent.

Question 16

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

Question 17

The reducing agent is reduced during the reaction.

Question 18

Oxidation is the loss of electrons.

Question 19

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

Question 20

The oxidation number of sodium in NaI is +1.

Question 21

Electrons flowing through a wire is an example of electrical current.

Question 22

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 23

Corrosion can be defined as the reduction of metals.

Question 24

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

Question 25

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

Question 26

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

Question 27

Alkaline batteries are used in automobiles.

Question 28

The cathode is the electrode at which reduction occurs.

Question 29

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

Question 30

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

Question 31

A galvanic cell is a spontaneous electrochemical cell.

Question 32

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

Question 33

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

Question 34

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

Question 35

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

Question 36

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

Question 37

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 38

Flashlight batteries are called dry cells.

Question 39

An electrolytic cell is a spontaneous redox reaction.

Question 40

Oxidation occurs at the cathode.

Question 41

Identify the substance being oxidized in the following reaction:
.

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

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

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

Question 44

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 45

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 46

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 47

Identify the reducing agent in the following reaction:
.

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

Question 48

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

Question 49

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

Question 50

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 51

The oxidation number of Cr in Cr₂O₇ ^2- is:

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

Question 52

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 53

Identify the oxidizing agent in the following reaction:
.

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

Question 54

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 55

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

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

Question 56

Identify the substance being reduced in the following reaction: .

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

Question 57

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 58

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) is the reducing agent and Zn²⁺ is the oxidizing agent.
E)none of the above

Question 59

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 60

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 61

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

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

Question 62

In which compound does manganese have the highest oxidation state?

A)Mn
B)Mn₂O₃
C)KMnO₄
D)MnO₂
E)none of the above

Question 63

What is the oxidation state of the underlined atom in the compound:
H₂S ?

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

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

What is the oxidation state of the underlined atom in the reaction:

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

Question 66

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 67

For the reaction KMnO₄ + Li → LiMnO₄ + K ,which atom is being reduced?

A)Li
B)Mn
C)O
D)K
E)none of the above

Question 68

The oxidation state of Na in Na₂SO₄ is:

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

Question 69

What is the balanced oxidation half-reaction for the following unbalanced redox reaction:

A)Ca → + 2
B) → Ag +
C)2 + Ca →
D) + 2 → 2Ag
E)none of the above

Question 70

The oxidation number of P in PO₄ ^3- is:

A)-3
B)-5
C)+5
D)+8
E)none of the above

Question 71

What is the oxidation state of the underlined atom in the reaction:

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

Question 72

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

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

Question 73

For the reaction Co + Cl₂ → CoCl₂ ,which statement is TRUE?

A)The cobalt is oxidized because its oxidation state changed from 0 to +2.
B)The cobalt is oxidized because it gained two electrons.
C)The oxidation state of each chlorine atom in Cl₂ is -1.
D)Each chlorine atom is oxidized.
E)none of the above

Question 74

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

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

Question 75

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 76

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 77

What is the oxidation state of nitrogen in N₂O₃?

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

Question 78

The oxidation state of Mn in KMnO₄ is:

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

Question 79

What is the oxidation state of the underlined atom in the reaction:

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

Question 80

What is the oxidation state of the underlined atom in the reaction:

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