Deck 19: Electrochemistry

Question 1

What element is being oxidized in the following redox reaction? H₂O₂(l)+ ClO₂(aq)→ ClO₂^-(aq)+ O₂(g)

A) H
B) O
C) Cl
D) N
E) C

Answer 1

O

Question 2

What element is being reduced in the following redox reaction? C₃H₈O₂(aq)+ K₂Cr₂O₇(aq)→ C₃H₄O₄(aq)+ Cr⁺³(aq)

A) C
B) H
C) O
D) K
E) Cr

Answer 2

Cr

Question 3

What element is being reduced in the following redox reaction? H₂O₂(l)+ ClO₂(aq)→ ClO₂⁻(aq)+ O₂(g)

A) H
B) O
C) Cl
D) N
E) C

Answer 3

Cl

Question 4

Identify the location of oxidation in an electrochemical cell.

A) the anode
B) the cathode
C) the electrode
D) the salt bridge
E) the socket

Question 5

What element is being oxidized in the following redox reaction? Cr(OH)₄^-(aq)+ ClO^-(aq)→ CrO₄^2-(aq)+ Cl^-(aq)

A) Cr
B) O
C) H
D) Cl

Question 6

Balance the following redox reaction if it occurs in acidic solution.What are the coefficients in front of H₂C₂O₄ and H₂O in the balanced reaction? MnO₄⁻(aq)+ H₂C₂O₄(aq)→ Mn²⁺(aq)+ CO₂(g)

A) H₂C₂O₄ = 5, H₂O = 8
B) H₂C₂O₄ = 1, H₂O = 1
C) H₂C₂O₄ = 5, H₂O = 1
D) H₂C₂O₄ = 1, H₂O = 4
E) H₂C₂O₄ = 3, H₂O = 2

Question 7

What element is being oxidized in the following redox reaction? MnO₄⁻(aq)+ H₂C₂O₄(aq)→ Mn²⁺(aq)+ CO₂(g)

A) C
B) O
C) Mn
D) H

Question 8

Identify the location of reduction in an electrochemical cell.

A) the anode
B) the cathode
C) the electrode
D) the salt bridge
E) the socket

Question 9

What element is being oxidized in the following redox reaction? C₃H₈O₂(aq)+ K₂Cr₂O₇(aq)→ C₃H₄O₄(aq)+ Cr⁺³(aq)

A) C
B) H
C) O
D) K
E) Cr

Question 10

Balance the following redox reaction if it occurs in acidic solution.What are the coefficients in front of H⁺ and Fe³⁺ in the balanced reaction? Fe²⁺(aq)+ MnO₄⁻(aq)→ Fe³⁺(aq)+ Mn²⁺(aq)

A) H⁺ = 2, Fe³⁺ = 3
B) H⁺ = 8, Fe³⁺ = 5
C) H⁺ = 3, Fe³⁺ = 2
D) H⁺ = 5, Fe³⁺ = 1
E) H⁺ = 8, Fe³⁺ = 1

Question 11

In a hydrogen-oxygen fuel cell,

A) neither oxygen or hydrogen atoms are oxidized or reduced.
B) both oxygen and hydrogen atoms are oxidized.
C) both oxygen and hydrogen atoms are reduced.
D) oxygen atoms are reduced and hydrogen atoms are oxidized.
E) oxygen atoms are oxidized and hydrogen atoms are reduced.

Question 12

What element is being reduced in the following redox reaction? Cr(OH)₄⁻(aq)+ ClO⁻(aq)→ CrO₄^2-(aq)+ Cl⁻(aq)

A) Cr
B) O
C) H
D) Cl

Question 13

In a hydrogen-oxygen fuel cell,

A) no transfer of electrons occurs.
B) both oxygen and hydrogen atoms lose electrons.
C) both oxygen and hydrogen atoms gain electrons.
D) oxygen atoms lose electrons and hydrogen atoms gain electrons.
E) oxygen atoms gain electrons and hydrogen atoms lose electrons.

Question 14

What element is being reduced in the following redox reaction? MnO₄⁻(aq)+ H₂C₂O₄(aq)→ Mn²⁺(aq)+ CO₂(g)

A) C
B) O
C) Mn
D) H

Question 15

In a voltaic cell,the anode is defined as

A) a metal contact.
B) the more positively charged electrode.
C) the positive terminal of the power source.
D) the more negatively charged electrode.
E) the negative terminal of the power source.

Question 16

Balance the following redox reaction if it occurs in basic solution.What are the coefficients in front of ClO₂ and H₂O in the balanced reaction? H₂O₂(l)+ ClO₂(aq)→ ClO₂⁻(aq)+ O₂(g)

A) ClO₂ = 1, H₂O = 1
B) ClO₂ = 1, H₂O = 2
C) ClO₂ = 4, H₂O = 3
D) ClO₂ = 4, H₂O = 2
E) ClO₂ = 2, H₂O = 2

Question 17

Define a salt bridge.

A) A pathway composed of salt water, that ions pass through.
B) A pathway in which no ions flow.
C) A pathway between the cathode and anode in which ions are reduced.
D) A pathway between the cathode and anode in which ions are oxidized.
E) A pathway by which counterions can flow between the half-cells without the solutions in the half-cell totally mixing.

Question 18

A voltaic cell

A) produces electrical current from a spontaneous chemical reaction.
B) produces electrical current from electricity.
C) consumes electrical current to drive a spontaneous chemical reaction.
D) produces electrical current from a nonspontaneous chemical reaction.
E) consumes electrical current to drive a nonspontaneous chemical reaction.

Question 19

Balance the following redox reaction if it occurs in basic solution.What are the coefficients in front of Br₂ and OH⁻ in the balanced reaction? Br₂(l)→ BrO₃⁻(aq)+ Br⁻(aq)

A) Br₂ = 1, OH⁻ = 2
B) Br₂ = 2, OH⁻ = 5
C) Br₂ = 3, OH⁻ = 3
D) Br₂ = 3, OH⁻ = 6
E) Br₂ = 1, OH⁻ = 6

Question 20

Balance the following redox reaction if it occurs in basic solution.What are the coefficients in front of Cr(OH)₄⁻ and ClO⁻ in the balanced reaction? Cr(OH)₄⁻(aq)+ ClO⁻(aq)→ CrO₄^2-(aq)+ Cl⁻(aq)

A) Cr(OH)₄⁻ = 2, ClO⁻ = 3
B) Cr(OH)₄⁻ = 1, ClO⁻ = 1
C) Cr(OH)₄⁻ = 1, ClO⁻ = 2
D) Cr(OH)₄⁻ = 2, ClO⁻ = 6
E) Cr(OH)₄⁻ = 6, ClO⁻ = 5

Question 21

Use the tabulated half-cell potentials to calculate ΔG° for the following balanced redox reaction. Pb²⁺(aq)+ Cu(s)→ Pb(s)+ Cu²⁺(aq)

A) -41 kJ
B) -0.47 kJ
C) +46 kJ
D) +91 kJ
E) -21 kJ

Question 22

Determine the cell notation for the redox reaction given below. 3 Cl₂(g)+ 2 Fe(s)→ 6 Cl⁻(aq)+ 2 Fe³⁺(aq)

A) Cl₂(g) ∣ Cl⁻(aq) ∣ Pt Fe(s) ∣ Fe³⁺(aq)
B) Cl⁻(aq) ∣ Cl₂(g) ∣ Pt Fe³⁺(aq) ∣ Fe(s)
C) Fe³⁺(aq) ∣ Fe(s) Cl⁻(aq) ∣ Cl₂(g) ∣ Pt
D) Fe(s) ∣ Cl₂(g) Fe³⁺(aq) ∣ Cl⁻(aq) ∣ Pt
E) Fe(s) ∣ Fe³⁺(aq) Cl₂(g) ∣ Cl⁻(aq) ∣ Pt

Question 23

Use the tabulated half-cell potentials to calculate ΔG° for the following balanced redox reaction. 3 I₂(s)+ 2 Fe(s)→ 2 Fe³⁺(aq)+ 6 I⁻(aq)

A) -1.1 × 10² kJ
B) +4.9 × 10¹ kJ
C) -9.7 × 10¹ kJ
D) +2.3 × 10² kJ
E) -3.3 × 10² kJ

Question 24

Use the standard half-cell potentials listed below to calculate the standard cell potential for the following reaction occurring in an electrochemical cell at 25°C.(The equation is balanced.) 3 Cl₂(g)+ 2 Fe(s)→ 6 Cl⁻(aq)+ 2 Fe³⁺(aq)
Cl₂(g)+ 2 e⁻ → 2 Cl⁻(aq)E° = +1.36 V
Fe³⁺(aq)+ 3 e⁻ → Fe(s)E° = -0.04 V

A) +4.16 V
B) -1.40 V
C) -1.32 V
D) +1.32 V
E) +1.40 V

Question 25

Calculate the cell potential for the following reaction that takes place in an electrochemical cell at 25°C. Sn(s)∣ Sn²⁺(aq,1.8 M) Ag⁺(aq,0.055 M)∣ Ag(s)

A) -0.94 V
B) -0.85 V
C) +1.02 V
D) +0.98 V
E) +0.86 V

Question 26

Calculate the cell potential for the following reaction that takes place in an electrochemical cell at 25°C. Sn(s)∣ Sn²⁺(aq,0.022 M) Ag⁺(aq,2.7 M)∣ Ag(s)

A) +1.01 V
B) -0.83 V
C) +1.31 V
D) +0.01 V
E) -0.66 V

Question 27

What statement is NOT true about standard electrode potentials?

A) E°_cell ^{is positive for spontaneous reactions.}
B) Electrons will flow from more negative electrode to more positive electrode.
C) The electrode potential of the standard hydrogen electrode is exactly zero.
D) E°_cell is the difference in voltage between the anode and the cathode.
E) The electrode in any half-cell with a greater tendency to undergo reduction is positively charged relative to the standard hydrogen electrode and therefore has a positive E°.

Question 28

Use the tabulated half-cell potentials to calculate ΔG° for the following redox reaction. 2 Al(s)+ 3 Mg²⁺(aq)→ 2 Al³⁺(aq)+ 3 Mg(s)

A) +4.1 × 10² kJ
B) +1.4 × 10² kJ
C) -2.3 × 10² kJ
D) -7.8 × 10² kJ
E) +6.8 × 10² kJ

Question 29

Identify the characteristics of a spontaneous reaction.

A) ΔG° < 0
B) ΔE°_cell > 0
C) K > 1
D) all of the above
E) none of the above

Question 30

Use the standard half-cell potentials listed below to calculate the standard cell potential for the following reaction occurring in an electrochemical cell at 25°C.(The equation is balanced.) Mg(s)+ Cu²⁺(aq)→ Cu(s)+ Mg²⁺(aq)
Mg²⁺(aq)+ 2 e⁻ → Mg(s)E° = -2.38 V
Cu²⁺(aq)+ 2 e⁻ → Cu(s)E° = +0.34 V

A) +2.04 V
B) -2.04 V
C) +2.72 V
D) -1.36 V
E) +1.36 V

Question 31

Use the standard half-cell potentials listed below to calculate the standard cell potential for the following reaction occurring in an electrochemical cell at 25°C.(The equation is balanced.) 2 K(s)+ I₂(s)→ 2 K⁺(aq)+ 2 I⁻(aq)
K⁺(aq)+ e⁻ → K(s)E° = -2.93 V
I₂(s)+ 2 e⁻ → 2 I⁻(aq)E° = +0.54 V

A) +6.40 V
B) +1.85 V
C) -5.32 V
D) +3.47 V
E) +5.32 V

Question 32

Use the standard half-cell potentials listed below to calculate the standard cell potential for the following reaction occurring in an electrochemical cell at 25°C.(The equation is balanced.) Pb(s)+ Br₂(l)→ Pb²⁺(aq)+ 2 Br⁻(aq)
Pb²⁺(aq)+ 2 e⁻ → Pb(s)E° = -0.13 V
Br₂(l)+ 2 e^- → 2 Br^-(aq)E° = +1.07 V

A) +1.20 V
B) +0.94 V
C) -0.94 V
D) -1.20 V
E) -0.60 V

Question 33

Use the standard half-cell potentials listed below to calculate the standard cell potential for the following reaction occurring in an electrochemical cell at 25°C.(The equation is balanced.) Sn(s)+ 2 Ag⁺(aq)→ Sn²⁺(aq)+ 2 Ag(s)
Sn²⁺(aq)+ 2 e⁻ → Sn(s)E° = -0.14 V
Ag⁺(aq)+ e⁻ → Ag(s)E° = +0.80 V

A) +1.74 V
B) +0.94 V
C) +1.08 V
D) -1.08 V
E) -1.74 V

Question 34

Use the tabulated half-cell potentials to calculate the equilibrium constant (K)for the following balanced redox reaction at 25°C. Pb²⁺(aq)+ Cu(s)→ Pb(s)+ Cu²⁺(aq)

A) 7.9 × 10^-8
B) 8.9 × 10⁷
C) 7.9 × 10¹⁵
D) 1.3 × 10^-16
E) 1.1 × 10^-8

Question 35

Which of the following reactions would have the smallest value of K at 298 K?

A) A + B → C; E°_cell = +1.22 V
B) A + 2 B → C; E°_cell = +0.98 V
C) A + B → 2 C; E°_cell = -0.030 V
D) A + B → 3 C; E°_cell = +0.15 V
E) More information is needed to determine.

Question 36

Identify a characteristic that does not describe a standard hydrogen electrode.

A) 1 M HCl solution with hydrogen gas
B) 1 atmosphere
C) zinc electrode
D) inert platinum electrode
E) potential of zero

Question 37

Use the tabulated half-cell potentials to calculate the equilibrium constant (K)for the following balanced redox reaction at 25°C. 3 I₂(s)+ 2 Fe(s)→ 2 Fe³⁺(aq)+ 6 I⁻(aq)

A) 3.5 × 10^-59
B) 1.1 × 10¹⁷
C) 2.4 × 10⁵⁸
D) 8.9 × 10^-18
E) 1.7 × 10²⁹

Question 38

Use the tabulated half-cell potentials to calculate the equilibrium constant (K)for the following balanced redox reaction at 25°C. 2 Al(s)+ 3 Mg²⁺(aq)→ 2 Al³⁺(aq)+ 3 Mg(s)

A) 1.1 × 10⁷²
B) 8.9 × 10^-73
C) 1.1 × 10^-72
D) 1.0 × 10²⁴
E) 4.6 × 10³¹

Question 39

Calculate the cell potential for the following reaction that takes place in an electrochemical cell at 25°C. Fe(s)∣ Fe³⁺(aq,0.0011 M) Fe³⁺(aq,2.33 M)∣ Fe(s)

A) +0.066 V
B) -0.036 V
C) 0.00 V
D) -0.099 V
E) +0.20 V

Question 40

Calculate the cell potential for the following reaction that takes place in an electrochemical cell at 25°C. Mg(s)∣ Mg²⁺(aq,2.74 M) Cu²⁺(aq,0.0033 M)∣ Cu(s)

A) -2.80 V
B) +2.62 V
C) +2.71 V
D) +2.12 V
E) -1.94 V

Question 41

In an electrolytic cell,the anode is defined as

A) a metal contact.
B) the more positively charged electrode.
C) the positive terminal of the power source.
D) the more negatively charged electrode.
E) the negative terminal of the power source.

Question 42

Identify the battery that is in most automobiles.

A) dry-cell battery
B) lithium ion battery
C) lead-acid storage battery
D) NiCad battery
E) fuel cell

Question 43

What mass of silver can be plated onto an object in 33.5 minutes at 8.70 A of current? Ag⁺(aq)+ e⁻ → Ag(s)

A) 19.6 g
B) 0.326 g
C) 9.78 g
D) 3.07 g
E) 0.102 g

Question 44

What is the reaction at the cathode in a breathalyzer?

A) Ethanol is oxidized to acetic acid.
B) Acetic acid is reduced to ethanol.
C) Oxygen is reduced.
D) Hydrogen is oxidized.
E) Ethanol is oxidized to acetaldehyde.

Question 45

What is the reaction at the anode in a breathalyzer?

A) Ethanol is oxidized to acetic acid.
B) Acetic acid is reduced to ethanol.
C) Oxygen is reduced.
D) Hydrogen is oxidized.
E) Ethanol is oxidized to acetaldehyde.

Question 46

In a nickel-cadmium battery,NiO(OH)is reduced to

A) Ni(OH)₄.
B) NiO₂.
C) Ni.
D) Ni(OH)₂.
E) NiOH.

Question 47

An electrolytic cell

A) produces electrical current from a spontaneous chemical reaction.
B) produces electrical current from electricity.
C) consumes electrical current to drive a spontaneous chemical reaction.
D) produces electrical current from a nonspontaneous chemical reaction.
E) consumes electrical current to drive a nonspontaneous chemical reaction.

Question 48

Calculate the cell potential for the following reaction that takes place in an electrochemical cell at 25°C. Cu(s)∣ Cu²⁺(aq,0.0032 M) Cu²⁺(aq,4.48 M)∣ Cu(s)

A) 0.00 V
B) +0.093 V
C) +0.34 V
D) +0.186 V
E) +0.052 V

Question 49

Identify the battery that is used as a common flashlight battery.

A) dry-cell battery
B) lithium ion battery
C) lead-acid storage battery
D) NiCad battery
E) fuel cell

Question 50

What mass of aluminum can be plated onto an object in 755 minutes at 5.80 A of current?

A) 73.5 g
B) 24.5 g
C) 220. g
D) 147 g
E) 8.17 g

Question 51

Describe how water can be a good conductor of current.

A) use pure water
B) heat the water
C) add salt
D) chill the water
E) vaporize the water

Question 52

In an alkaline battery,MnO₂ is reduced to

A) MnO₃.
B) Mn₂O₂.
C) MnO(OH).
D) MnO₄^-.
E) Mn₂O₃.

Question 53

Identify the battery type that has a high overcharge tolerance.

A) NiCad
B) Li ion
C) NiMH
D) lead storage
E) none of the above

Question 54

In a lead-acid storage battery,PbO₂ is reduced to

A) Pb.
B) PbSO₄.
C) Pb₂O.
D) PbO₃.
E) PbO.

Question 55

In a dry-cell battery,MnO₂ is reduced to

A) MnO₃.
B) Mn₂O₂.
C) MnO(OH).
D) MnO₄^-.
E) Mn₂O₃.

Question 56

Identify the components of a fuel cell.

A) nickel-metal hydride
B) lithium ion
C) hydrogen-oxygen
D) nickel-cadmium
E) zinc-manganese

Question 57

Nickel can be plated from aqueous solution according to the following half reaction.How long would it take (in min)to plate 29.6 g of nickel at 4.7 A? Ni²⁺(aq)+ 2 e⁻ → Ni(s)

A) 1.7 × 10² min
B) 5.9 × 10² min
C) 3.5 × 10² min
D) 4.8 × 10² min
E) 6.2 × 10² min

Question 58

In a lead-acid storage battery,Pb is oxidized to

A) PbO₂.
B) PbSO₄.
C) Pb₂O.
D) PbO₃.
E) PbO.

Question 59

In a nickel-metal hydride battery,NiO(OH)is reduced to

A) Ni(OH)₄.
B) NiO₂.
C) Ni.
D) Ni(OH)₂.
E) NiOH.

Question 60

Calculate the cell potential for the following reaction that takes place in an electrochemical cell at 25°C. Al(s)∣ Al³⁺(aq,0.115 M) Al³⁺(aq,3.89 M)∣ Al(s)

A) +1.66 V
B) +0.060 V
C) 0.00 V
D) +0.090 V
E) +0.030 V

Question 61

Balance the following reaction in KOH.What are the coefficients in front of C₉H₂₀O₂ and KMnO₄ in the balanced reaction? C₉H₂₀O₂(aq)+ KMnO₄(aq)→ C₉H₁₄O₄K₂(aq)+ MnO₂(aq)

A) C₉H₂₀O₂ = 3, KMnO₄ = 8
B) C₉H₂₀O₂ = 3, KMnO₄ = 4
C) C₉H₂₀O₂ = 8, KMnO₄ = 4
D) C₉H₂₀O₂ = 2, KMnO₄ = 8
E) C₉H₂₀O₂ = 3, KMnO₄ = 2

Question 62

What element is being oxidized in the following redox reaction? C₁₀H₂₂O₂(aq)+ KMnO₄(aq)→ C₁₀H₁₆O₄K₂(aq)+ MnO₂(aq)

A) C
B) H
C) O
D) K
E) Mn

Question 63

What element is being oxidized in the following redox reaction? Mg²⁺(aq)+ NH₄⁺(aq)→ Mg(s)+ NO₃⁻(aq)

A) Mg
B) N
C) H
D) O

Question 64

What element is being reduced in the following redox reaction? C₃H₈O₂(aq)+ KMnO₄(aq)→ C₃H₂O₄K₂(aq)+ MnO₂(aq)

A) C
B) H
C) O
D) K
E) Mn

Question 65

A sacrificial electrode is composed of a metal that

A) does not serve as a protective coating.
B) reduces more easily than iron.
C) has an oxide that is crumbly when formed.
D) oxidizes more easily than iron.
E) oxidizes the same as iron.

Question 66

Aluminum is quickly oxidized in the air to form

A) Al₂O₃.
B) Al(OH)₂.
C) Al(OH)₃.
D) Al₃O₂.
E) AlO.

Question 67

Predict the species that will be reduced first if the following mixture of molten salts undergoes electrolysis. Na⁺,Ca²⁺,Cl⁻,Br⁻,F⁻

A) Na⁺
B) Cl^-
C) Ca²⁺
D) Br^-
E) F^-

Question 68

Predict the species that will be reduced first if the following mixture of molten salts undergoes electrolysis. Zn²⁺,Fe³⁺,Mg²⁺,Br^-,I^-

A) Zn²⁺
B) Mg²⁺
C) Br^-
D) Fe³⁺
E) I^-

Question 69

Identify a component in the formation of rust.

A) salt
B) moisture
C) acid
D) all of the above
E) none of the above

Question 70

Define extraction.

A) Free metal is oxidized out of its ore.
B) Undesired reduction of metals from reducing agents in the environment
C) Plating a film on a metal to protect it
D) Undesired oxidation of metals from oxidizing agents in the environment
E) Free metal is reduced out of its ore.

Question 71

Identify oxidation.

A) increase in oxidation number
B) loss of electrons
C) gain of protons
D) loss of neutrons
E) both A and B

Question 72

Balance the following redox reaction if it occurs in basic solution.What are the coefficients in front of Cr and Cl₂ in the balanced reaction? Cr(s)+ Cl₂(g)→ Cr³⁺(aq)+ Cl^-(aq)

A) Cr = 2, Cl₂ = 3
B) Cr = 2, Cl₂ = 4
C) Cr = 1, Cl₂ = 2
D) Cr = 2, Cl₂ = 1
E) Cr = 3, Cl₂ = 2

Question 73

Predict the species that will be oxidized first if the following mixture of molten salts undergoes electrolysis. Cu²⁺,Mg²⁺,Cl⁻,Br⁻,F⁻

A) Cl^-
B) F^-
C) Cu²⁺
D) Mg²⁺
E) Br^-

Question 74

Balance the following redox reaction if it occurs in H₂SO₄.What are the coefficients in front of C₁₀H₂₂O₂ and H₂SO₄ in the balanced reaction? C₁₀H₂₂O₂(aq)+ Na₂Cr₂O₇(aq)→ C₁₀H₁₈O₄(aq)+ Cr₂(SO₄)₃(aq)

A) C₁₀H₂₂O₂ = 3, H₂SO₄ = 4
B) C₁₀H₂₂O₂ = 2, H₂SO₄ = 8
C) C₁₀H₂₂O₂ = 1, H₂SO₄ = 16
D) C₁₀H₂₂O₂ = 3, H₂SO₄ = 16
E) C₁₀H₂₂O₂ = 2, H₂SO₄ = 4

Question 75

Balance the following redox reaction if it occurs in acidic solution.What are the coefficients in front of Fe and Ag⁺ in the balanced reaction? Fe(s)+ Ag⁺(aq)→ Ag(s)+ Fe²⁺(aq)

A) Fe = 1, Ag⁺ = 2
B) Fe = 1, Ag⁺ = 3
C) Fe = 2, Ag⁺ = 1
D) Fe = 2, Ag⁺ = 3
E) Fe = 3, Ag⁺ = 3

Question 76

Define corrosion.

A) Free metal is oxidized out of its ore.
B) Undesired reduction of metals from reducing agents in the environment
C) Plating a film on a metal to protect it
D) Undesired oxidation of metals from oxidizing agents in the environment
E) Free metal is reduced out of its ore.

Question 77

Balance the following redox reaction if it occurs in acidic solution.What are the coefficients in front of Pb and H⁺ in the balanced reaction?
Pb²⁺(aq)+ NH₄⁺(aq)? Pb(s)+ NO₃?(aq)

A) Pb = 1, H? = 8
B) Pb = 1, H? = 2
C) Pb = 4, H? = 10
D) Pb = 2, H? = 3
E) Pb = 3, H? = 5

Question 78

To prevent rust,nails are coated with

A) zinc.
B) salt.
C) calcium.
D) sodium.
E) lithium.

Question 79

Balance the following redox reaction if it occurs in H₂SO₄.What are the coefficients in front of H₂O and Cr₂(SO₄)₃ in the balanced reaction? C₇H₁₆O₂(aq)+ Na₂Cr₂O₇(aq)→ C₇H₁₂O₄(aq)+ Cr₂(SO₄)₃(aq)

A) H₂O = 1, Cr₂(SO₄)₃ = 5
B) H₂O = 5, Cr₂(SO₄)₃ = 2
C) H₂O = 11, Cr₂(SO₄)₃ = 4
D) H₂O = 22, Cr₂(SO₄)₃ = 4
E) H₂O = 8, Cr₂(SO₄)₃ = 4

Question 80

Describe the reactions during the electrolysis of water.

A) Oxygen is reduced and hydrogen is oxidized.
B) Oxygen and hydrogen are both oxidized.
C) Oxygen and hydrogen are both reduced.
D) Oxygen is oxidized and hydrogen is reduced.
E) Neither oxygen nor hydrogen are oxidized or reduced.