Deck 19: Oxidation-Reduction Redoxreactions

Question 1

Examine the two beakers shown below.
If the metals were connected by a wire containing a meter and the two solutions by a salt bridge,the meter shows are reading of 0.95 V.Which of the following is correct?

A)A spontaneous reaction occurs.
B)A voltaic cell has been constructed.
C)Electrons flow from the anode to the cathode.
D)Reduction occurs at the cathode.
E)All of the above are correct in this situation.

Answer 1

All of the above are correct in this situation.

Question 2

Consider the following images.The reactions occurring in each are shown in the choices.


A B C D
Which of the following is an example of an electron transfer reaction?

A)Pb(NO₃)₂(aq)+ Na₂SO₄(aq) 2 NaNO₃(aq)+ PbSO₄(s)
B)H₂CO₃(aq) H₂O(l)+ CO₂(g)
C)Ca(s)+ 2HCl(aq) CaCl₂(aq)+ H₂(g)
D)Zn(s)+ Cu²⁺(aq) Zn²⁺(aq)+ Cu(s)
E)Both c and d are electron transfer reactions.

Answer 2

Both c and d are electron transfer reactions.

Question 3

Which of the following processes is a reduction reaction?

A)2 Br^- becoming Br₂
B)Ni²⁺ becoming Ni³⁺
C)Hg₂²⁺ becoming 2 Hg
D)Tin(II)becoming tin(IV)
E)Iron(II)becoming iron(III)

Answer 3

Hg₂²⁺ becoming 2 Hg

Question 4

What is the balanced redox equation that results from the combination of the following half-reactions?
Cr³⁺ + 3e^-
Cr and 2 Cl^-
Cl₂ + 2 e^-

A)CrCl₂⁺ + e^- Cr + Cl₂
B)Cr³⁺ + 2 Cl^- + e^- Cr + Cl₂
C)Cr³⁺ + 3 Cl^- CrCl₃
D)2 Cr³⁺ + 6 Cl^- + 3 e^- 3 Cl₂ + 2 Cr + 2 e^-
E)2 Cr³⁺ + 6 Cl^- 3 Cl₂ + 2 Cr

Question 5

What is the oxidation number of Cl in Cl₂?

A)-1
B)-2
C)+2
D)0
E)One atom is +1 and the other is -1.

Question 6

Identify the reduction half-reaction in the redox equation:
4 Ag + O₂(g)+ 2 H₂O
4 Ag⁺ + 4 OH^-

A)Ag Ag + e^-
B)4 Ag + 4 e^- 4 Ag⁺
C)2 H₂O + 2e^- 4 OH^-
D)O₂(g)+ 2 H₂O + 4 e^- 4 OH^-
E)2 H₂O + 2 e^- H₂ + 2 OH^-

Question 7

What is the half-reaction for the oxidation of sulfide ions in aqueous solution?

A)S^2-(aq) S(s)+ 2 e^-
B)S-(aq)+ e^- S^2-(aq)
C)S(s)+ 2 e^- S^2-(aq)
D)SO₃^2-(aq)+ 6 H⁺(aq) S(s)+ 3 H₂O( )+ 4 e^-
E)SO₄^2-(aq)+ 8 H⁺(aq) S(s)+ 4 H₂O( )+ 6 e^-

Question 8

Oxidation-reduction reactions are also known as...

A)electron-transfer reactions
B)proton-transfer reactions
C)neutron bombardment reactions
D)neutralization reactions
E)double displacement reactions

Question 9

Identify the oxidation half-reaction in the redox equation:
Cu(s)+ Cl₂(g)
Cu²⁺ + 2 Cl^-

A)Cl₂ 2 Cl^- + 2 e^-
B)Cl₂ + 2 e^- 2 Cl^-
C)Cu Cu²⁺ + 2 e^-
D)Cu + 2 e^- Cu²⁺
E)Cu + Cl₂ + 2 e^- Cu²⁺ + 2 Cl^- + 2 e^-

Question 10

What is the oxidation number of titanium in TiO₂?

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

Question 11

Which among the following are the parts that comprose an electrolytic cell?
(i)Two electrodes
(ii)A molecular liquid
(iii)A salt bridge
(iv)An ionic solution

A)i and ii
B)i and iv
C)ii,iii,and iv
D)i,ii,and iii
E)i,iii,and iv

Question 12

What happens in a galvanic cell?

A)Cations are changed into ions
B)Chemical energy is converted to electrical energy
C)Anions combine with cations to produce electricity
D)Less reactive metals are turned into more reactive metals by the action of an electric current
E)Matter is changed into energy

Question 13

Reduction can be defined as...

A)a increase in oxidation number
B)the gain of protons
C)the loss of protons
D)a gain of electrons
E)a loss of electrons

Question 14

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

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

Question 15

Consider the following beakers.In the beaker on the left copper metal is placed in a solution of silver nitrate.The reaction is allowed to run for 60 minutes producing the products shown on the right.
The equation for the oxidation half-reaction would be:

A)
B)
C)
D)

Question 16

Identify the oxidation half-reaction in the following group.

A)Ag(NH₃)₂ + e^- Ag + 2 NH₃
B)Ag + Cl^- AgCl + e^-
C)PbSO₄(s)+ 2 e^- Pb(s)+ SO₄^2-
D)Ag(CN)₂ + e^- Ag + 2 CN^-
E)Cr₂O₇^2- + H₂O 2 CrO₄^2- + 2 H⁺

Question 17

Which of the following is the half-reaction for reduction of chlorine to chloride ions in water?

A)Cl₂(aq) Cl^-(aq)+ Cl⁺(aq)
B)Cl^-(aq)+ H⁺(aq) HCl(aq)
C)2 Cl^-(aq)+ 2 e^- Cl₂(aq)
D)Cl₂(aq)+ 2 e^- 2 Cl^-(aq)
E)2 Cl^-(aq) Cl₂(aq)+ 2 e^-

Question 18

Which of the following statements is correct for an electrolytic cell?

A)Electrons flow through the external circuit from the anode to the cathode
B)The electrode at which oxidation occurs is the cathode
C)The reaction occurring in the cell can be used to generate an electric current.
D)Charge is carried through the solution by electrons in one direction and by protons in the other direction
E)None of the statements above is correct

Question 19

How many electrons are transferred in the balanced redox equation that results from combining these two half-reactions on a molar scale?
Al
Al³⁺ + 3e^- and Cu²⁺ + 2 e^-
Cu

A)6
B)5
C)3
D)2
E)1

Question 20

Which of the following is a reduction reaction?

A)Conversion of 2 Cl^- to Cl₂
B)Conversion of copper(I)ions into copper(II)ions
C)Conversion of Ag⁺ into Ag
D)Conversion of Al³⁺ to Al
E)Conversion of plutonium into uranium

Question 21

In comparing acid-base neutralization reactions and redox reactions,which of the following is correct?

A)A strong acid readily gains protons while a strong oxidizing agent readily gains electrons.
B)A strong acid readily provides protons while a strong reducing agent readily gains electrons.
C)A strong base readily gains protons while a strong oxidizing agent readily gains electrons.
D)A strong base readily provides protons while a strong reducing agent readily loses electrons.

Question 22

What role does the reducing agent play in a redox reaction?

A)It catalyzes the reaction
B)It picks up electrons
C)It picks up protons from the oxidizing agent
D)It donates protons to the oxidizing agent
E)It donates some of its electrons

Question 23

What is the reducing agent in the reaction of hydrazine as a rocket fuel: N₂H₄( )+ O₂(g) N₂(g)+ 2 H₂O( )?

A)N₂H₄
B)O₂
C)N₂
D)H₂O
E)There is no reducing agent in this reaction

Question 24

In the reaction of carbon with oxygen,which substance is oxidized? The equation for the reaction is
C(s)+ O₂(g)
CO₂(g).

A)O₂(g)
B)CO₂(g)
C)No substance is oxidized in this reaction
D)C(s)
E)Both C(s)and O₂(g)

Question 25

Consider the following table of relative strengths of oxidizing and reducing agents:
Oxidizing Agent
Reducing Agent
Stronger
A⁺ + e^-
A
Weaker
$\downarrow$
B²⁺ + 2 e^-
B
$\uparrow$
Weaker
C³⁺ + 3 e^-
C
Stronger
Which of the following is the correct net ionic equation for the redox reaction between A⁺ and C and the correct direction that is favored?

A)A⁺ + C A + C³⁺ forward
B)A⁺ + C A + C³⁺ reverse
C)3 A⁺ + C 3 A + C³⁺ forward
D)3 A⁺ + C 3 A + C³⁺ reverse
E)A⁺ + C + e^- A + C³⁺ + 3 e^- forward

Question 26

When zinc is plated to iron,the zinc corrodes rather than the iron.Which statement is true?

A)Zinc is less reactive than iron
B)Zinc is more active metal than iron
C)Zinc is a better oxidizing agent than iron
D)Iron is a better reducing agent than zinc
E)Both metals are Lewis metals

Question 27

Which of the following substances is most likely to be a reducing agent?

A)NH₄⁺
B)S^2-
C)Mg²⁺
D)KMnO₄
E)Cl₂

Question 28

Which of the following is the correct net ionic equation for the redox reaction between nickel ion and metallic silver and the correct direction that is favored? The half reactions are:
Ag⁺ + e^-
Ag(s)Ni²⁺ + 2e^-
Ni(s)Ag⁺ is a stronger oxidizing agent than Ni²⁺.

A)Ni²⁺(aq)+ Ag(s)+ e^- Ni(s)+ Ag⁺ (aq)forward
B)Ni²⁺(aq)+ Ag(s)+ e^- Ni(s)+ Ag⁺(aq)reverse
C)Ni²⁺(aq)+ Ag(s) Ni(s)+ 2 Ag⁺(aq)reverse
D)Ni²⁺(aq)+ 2 Ag(s) Ni(s)+ 2 Ag⁺(aq)forward
E)Ni²⁺(aq)+ 2 Ag(s) Ni(s)+ 2 Ag⁺(aq)reverse

Question 29

Which of the following statements is incorrect?

A)Acid-base reactions involve a transfer of protons; redox reactions,a transfer of electrons
B)In both redox and acid-base reactions,the reactants are given special names to indicate their roles in the transfer process
C)Just as certain species can either donate or accept protons and thereby behave as an acid in one reaction and a base in another,certain species can either accept or donate electrons,acting as an oxidizing agent in one reaction and a reducing agent in another
D)Just as acids and bases may be classified as "strong" or "weak" depending on how readily they donate or accept protons,the strengths of oxidizing and reducing agents may be compared according to their tendencies to attract or release electrons
E)Unlike most acid-base reactions in aqueous solution,which reach a state of equilibrium,most aqueous redox reactions do not reach a state of equilibrium and proceed entirely in either the forward or reverse direction

Question 30

Which of the following is the correct net ionic equation for the redox reaction between zinc and the copper(II)ion and the correct direction that is favored? The half-reactions are:
Cu²⁺ + 2 e^-
Cu(s)Zn²⁺ + 2 e^-
Zn(s)Cu²⁺ is a stronger oxidizing agent than Zn²⁺.

A)Cu²⁺(aq)+ Zn(s) Cu(s)+ Zn²⁺(aq)reverse
B)Cu²⁺(aq)+ Zn(s) Cu(s)+ Zn²⁺(aq)forward
C)Cu²⁺(aq)+ Zn²⁺(s) Cu(s)+ Zn(s) reverse
D)Cu²⁺(aq)+ Zn²⁺(s) Cu(s)+ Zn(s) forward
E)Zn(s)+ Cu²⁺(aq) Zn⁺(aq)+ Cu⁺(aq)forward

Question 31

Which of the following cannot be a reducing agent?

A)H⁺(aq)
B)H₂(g)
C)H₂O₂( )
D)CH₄(g)
E)All of the above can be a reducing agent

Question 32

What is the oxidizing agent in this redox reaction?
2 MnO₂(s)+ 2 NH₄Cl(s)+ Zn(s)
Zn(NH₃)₂Cl₂(s)+ Mn₂O₃(s)+ H₂O( )

A)NH₄Cl
B)MnO₂
C)Zn
D)Zn(NH₃)₂Cl₂
E)Mn₂O₃

Question 33

Match each term with its correct classification:
Proton Donor Proton Acceptor Electron Donor Electron Acceptor

A)Reducing Agent Oxidizing Agent Acid Base
B)Base Acid Reducing Agent Oxidizing Agent
C)Base Acid Oxidizing Agent Reducing Agent
D)Acid Base Reducing Agent Oxidizing Agent
E)Acid Base Oxidizing Agent Reducing Agent

Question 34

What happens to an elemental oxidizing agent in a redox reaction?

A)It speeds the rate of the reaction although it doesn't actually participate in the reaction
B)It gives up some of its electrons
C)It increases the oxidation number
D)It gets oxidized
E)It gets reduced

Question 35

What is the oxidation number of chromium in Cr₂O₇^2-?

A)+12
B)+3
C)+6
D)-2
E)-1

Question 36

Silver metal will not react with hydrochloric acid.What does this suggest about silver and hydrochloric acid?

A)HCl is a weak acid
B)HCl is a strong acid
C)Ag is a weaker reducing agent than H⁺ in HCl(aq)
D)Ag is a stronger oxidizing agent than HCl
E)No conclusion can be made based on this information

Question 37

What evidence suggests that Na⁺ ions are very weak oxidizing agents?

A)NaCl is a strong electrolyte
B)Na metal does not occur in the Earth's crust
C)NaOH is a strong base
D)Na metal is soft and can be cut with a knife
E)Na⁺ ions are a component of table salt

Question 38

Which substance gets reduced in this redox reaction?
Pb(s)+ PbO₂(s)+ 2 H₂SO₄(aq)
2 PbSO₄(s)+ 2 H₂O( )

A)H₂SO₄(s)
B)Pb(s)
C)PbO₂(s)
D)PbSO₄(s)
E)No substance is reduced in this reaction

Question 39

Balance the following redox reaction in acidic solution and determine how many water molecules are in the equation.
MnO₄^- + ClO^-
ClO₃^- + Mn²⁺ + H₂O

A)8
B)2
C)6
D)5
E)4

Question 40

Consider the following table of relative strengths of oxidizing and reducing agents:
Oxidizing Agent
Reducing Agent
Stronger
A⁺ + e^-
A
Weaker
$\downarrow$
B²⁺ + 2 e^-
B
$\uparrow$
Weaker
C³⁺ + 3 e^-
C
Stronger
Which correctly lists the oxidizing agents in order of increasing strength?

A)A < B < C
B)C < B < A
C)A⁺ < B²⁺ < C³⁺
D)B²⁺ < A⁺ < C³⁺
E)C³⁺ < B²⁺ < A⁺

Question 41

Balance the half-reaction in acidic solution and determine the coefficient for hydrogen ion:
___ Cr³⁺ + ___ H₂O
___ Cr₂O₇^2- + ___ H⁺

A)2
B)5
C)8
D)11
E)14

Question 42

In balancing the half-reaction
SO₄^2-(aq)
S(s)how many H⁺ ions are added to which side?

A)4 H⁺ to the left side
B)8 H⁺ to the right side
C)4 H⁺ to the right side
D)8 H⁺ to the left side
E)6 H⁺ to the left side

Question 43

Balance the following redox equation in acidic solution and determine the coefficient placed in front of H₂O: ___ Cu + ___ NO₃^- + ___ H⁺ ___ Cu²⁺ + ___ NO + ___ H₂O

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

Question 44

In balancing the half-reaction
NO(g)
NO₃^-(aq)in acidic solution,how many electrons are added,and to which side?

A)1 electron to the right side
B)3 electrons to the left side
C)5 electrons to the left side
D)5 electrons to the right side
E)3 electrons to the right side