Deck 19: Electrochemistry

Question 1

What is the name given to the experimental apparatus for generating electricity through the use of a spontaneous redox reaction?

A) Electrolytic cell
B) Galvanic cell
C) Redox cell
D) Cathode
E) Anode

Answer 1

Galvanic cell

Question 2

Consider the following redox equation. Mn(OH)₂(s) + MnO₄^-(aq) → MnO₄^2-(aq) (basic solution)
When the equation is balanced with the smallest whole number coefficients, what is the coefficient for OH^-(aq) and on which side of the equation is OH^-(aq) present?

A) 4, reactant side
B) 4, product side
C) 6, reactant side
D) 6, product side
E) 8, reactant side

Answer 2

6, reactant side

Question 3

Which statement is correct?

A) The cathode is the electrode where the oxidation takes place.
B) The cathode is the electrode where the reduction takes place.
C) Both oxidation and reduction make take place at the cathode, depending on the cell.
D) The cathode is always positive.
E) The anode is always negative.

Answer 3

The cathode is the electrode where the reduction takes place.

Question 4

When the following equation is balanced with the lowest whole number coefficients, the coefficients are: Cu(s) + H⁺(aq) + NO₃^-(aq) → NO(g) + H₂O(l) + Cu²⁺(aq)

A) 1, 2, 1, 1, 1, 1
B) 3, 2, 1, 1, 1, 3
C) 3, 2, 4, 2, 4, 3
D) 1, 8, 2, 2, 4, 1
E) 3, 8, 2, 2, 4, 3

Question 5

If a substance is reduced, it must undergo a

A) gain of electrons.
B) loss of oxygen.
C) gain of hydrogen.
D) loss of electrons.
E) gain of oxygen.

Question 6

When the following redox equation is balanced with the smallest whole number coefficients, what is the coefficient of Sn(OH)₃^-? Bi(OH)₃(s) + Sn(OH)₃^-(aq) → Sn(OH)₆^2-(aq) + Bi(s) (basic solution)

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

Question 7

Consider the reaction CuO(s) + H₂(g) → Cu(s) + H₂O(l)
In this reaction, which substances are the oxidizing agent and reducing agent, respectively?

A) CuO and H₂
B) H₂ and CuO
C) CuO and Cu
D) H₂O and H₂
E) Cu and H₂O

Question 8

Complete and balance the following redox equation using the set of smallest whole numbers coefficients. What is the sum of the coefficients? HI + HNO₃ → I₂ + NO (acidic solution)

A) 5
B) 7
C) 14
D) 17
E) None of these choices is correct.

Question 9

When the following redox equation is balanced with the smallest whole number coefficients, the coefficient for the hydrogen sulfate ion will be ________. Al(s) + HSO₄^-(aq) + OH^-(aq) → Al₂O₃(s) + S^2-(aq) + H₂O(l)

A) 1
B) 3
C) 4
D) 6
E) 8

Question 10

Complete and balance the following redox equation. Now sum the coefficients of all species in the balanced equation. (Remember to add the coefficients that are equal to one, and to add the coefficients of any species added to the equation.) The sum of the smallest whole number coefficients is Bi(OH)₃ + SnO₂^2- → Bi + SnO₃^2- (basic solution)

A) 32
B) 25
C) 16
D) 13
E) 4

Question 11

What is the name given to the apparatus where oxidation occurs in a cell where electricity flows?

A) Cathode
B) Electrode
C) Galvanic cell
D) Anode
E) Voltaic cell

Question 12

Which is not a redox reaction?

A) Al(OH)₄^-(aq) + 4H⁺(aq) → Al³⁺(aq) + 4H₂O(l)
B) C₆H₁₂O₆(s) + 6O₂(g) → 6CO₂(g) + 6H₂O(l)
C) Na₆FeCl₈(s) + 2Na(l) → 8NaCl(s) + Fe(s)
D) 2H₂O₂(aq) → 2H₂O(l) + O₂(g)
E) CO₂(g) + H₂(g) → CO(g) + H₂O(g)

Question 13

Complete and balance the following redox equation. When properly balanced using the smallest whole-number coefficients, the coefficient of S is H₂S + HNO₃ → S + NO + H₂O (acidic solution)

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

Question 14

When the following redox equation is balanced with the smallest whole number coefficients, what is the coefficient of Sb³⁺(aq)? BrO₃^-(aq) + Sb³⁺(aq) → Br^-(aq) + Sb⁵⁺(aq) (acidic solution)

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

Question 15

When the following redox equation is balanced using the smallest whole-number coefficients, what is the coefficient of NO₂? Sn + HNO₃ → SnO₂ + NO₂ + H₂O (acidic solution)

A) 1
B) 2
C) 3
D) 4
E) 5

Question 16

When the following redox equation is balanced with the smallest whole number coefficients, what is the coefficient for nitrogen dioxide? I₂(s) + HNO₃(aq) → HIO₃(aq) + NO₂(g) + H₂O(l)

A) 1
B) 2
C) 4
D) 5
E) 10

Question 17

What is the oxidizing agent in the (unbalanced) reaction? Cu(s) + H⁺(aq) + NO₃^-(aq) → NO(g) + H₂O(l) + Cu²⁺(aq)

A) Cu
B) H⁺
C) (NO₃^-)
D) NO
E) Cu²⁺

Question 18

When the following redox equation is balanced with the smallest whole number coefficients, what is the coefficient of Zn(s)? Zn(s) + ReO₄^-(aq) → Re(s) + Zn²⁺(aq) (acidic solution)

A) 2
B) 7
C) 8
D) 16
E) None of these choices is correct.

Question 19

Consider the following balanced redox reaction. 3CuO(s) + 2NH₃(aq) → N₂(g) + 3H₂O(l) + 3Cu(s)
Which of the following statements is true?

A) CuO(s) is the oxidizing agent and copper is reduced.
B) CuO(s) is the oxidizing agent and copper is oxidized.
C) CuO(s) is the reducing agent and copper is oxidized.
D) CuO(s) is the reducing agent and copper is reduced.
E) CuO(s) is the oxidizing agent and N₂(g) is the reducing agent.

Question 20

Consider the following balanced redox reaction. Mn²⁺(aq) + S₂O₈^2-(aq) + 2H₂O(l) → MnO₂(s) + 4H⁺(aq) + 2SO₄^2-(aq)
Which of the following statements is true?

A) Mn²⁺(aq) is the oxidizing agent and is reduced.
B) Mn²⁺(aq) is the oxidizing agent and is oxidized.
C) Mn²⁺(aq) is the reducing agent and is oxidized.
D) Mn²⁺(aq) is the reducing agent and is reduced.
E) Manganese does not change its oxidation number in this reaction.

Question 21

The redox reaction of peroxydisulfate with iodide has been used for many years as part of the iodine clock reaction. If E°_cell= 1.587 V and E° of the cathode half-cell is 0.536 V, what is E° of the anode half-cell? S₂O₈^2-(aq) + 2H⁺ + 2I ^-(aq) → 2HSO₄^-(aq) + I₂(aq)

A) -1.051 V
B) -2.123 V
C) 1.051 V
D) 2.123 V
E) None of these choices is correct.

Question 22

The voltaic cell composed of Co(s), Co²⁺(aq), Cu(s), and Cu²⁺(aq) has E°_cell = 0.62 V. If E° of the cathode half-cell is 0.34 V, what is E° of the anode half-cell? Cu²⁺(aq) + Co(s) → Cu(s) + Co²⁺(aq)

A) -0.28 V
B) -0.96 V
C) 0.28 V
D) 0.96 V
E) 0.21 V

Question 23

If E° for X + e^- → Y is larger than E° for A + 2e^- → B, then in a spontaneous process under standard-state conditions,

A) X will oxidize A.
B) Y will oxidize A.
C) Y will reduce A.
D) B will oxidize X.
E) B will reduce X.

Question 24

A voltaic cell is prepared using copper and silver. Its cell notation is shown below. Cu(s) | Cu²⁺(aq) || Ag⁺(aq) | Ag(s)
Which reaction occurs at the cathode?

A) Cu(s) → Cu²⁺(aq) + 2e^-
B) Cu²⁺(aq) + 2e^- → Cu(s)
C) Ag(s) → Ag⁺(aq) + e^-
D) Ag⁺(aq) + e^- → Ag(s)
E) Cu(s) + 2Ag⁺(aq) → Cu²⁺(aq) + 2Ag(s)

Question 25

What is E°_cell for the following reaction? 2 Ag(s) + Sn²⁺(aq) → 2 Ag⁺(aq) + Sn(s)

A) +0.94 V
B) -0.94 V
C) +0.67 V
D) -0.67 V
E) +1.34 V

Question 26

What is the name given to the apparatus that connects the two solutions by a conducting medium through which the cations and anions can move from one half-cell to the other?

A) Cathode
B) Electrode
C) Galvanic cell
D) Salt bridge
E) Fuel cell

Question 27

Which is incorrect?

A) At equilibrium, E_cell = 0.
B) E > 0 for a spontaneous process.
C) E = 0 for a spontaneous process.
D) ΔG < 0 for a spontaneous process.
E) ΔG = 0 at equilibrium.

Question 28

A voltaic cell prepared using aluminum and nickel has the following cell notation. Al(s) | Al³⁺(aq) || Ni²⁺(aq) | Ni(s)
Which reaction occurs at the anode?

A) Al(s) → Al³⁺(aq) + 3e^-
B) Al³⁺(aq) + 3e^- → Al(s)
C) Ni(s) → Ni²⁺(aq) + 2e^-
D) Ni²⁺(aq) + 2e^- → Ni(s)
E) Ni(s) + Ni²⁺(aq) → Al(s) + Al³⁺(aq)

Question 29

What is E°_cell for the following reaction? Al(s) + 3Ag⁺(aq) → Al³⁺(aq) + 3Ag(s)

A) -2.46 V
B) 0.86 V
C) -0.86 V
D) 2.46 V
E) 4.06 V

Question 30

What is E°_cell for the following reaction? 2Au(s) + 3Ca²⁺(aq) → 2Au³⁺(aq) + 3Ca(s)

A) -4.37 V
B) -1.37 V
C) -11.6 V
D) 1.37 V
E) 4.37 V

Question 31

What is meant by SHE?

A) Shared half electrodes
B) Shifting half of the electricity
C) Standard hydrogen electrode
D) Small helium electrode
E) Standard Hg electrode

Question 32

What is E°_cell for a galvanic cell represented by the combination of the following half-reactions?

A) -0.398 V
B) -2.380 V
C) 0.398 V
D) 2.380 V
E) 6.539 V

Question 33

What is the purpose of a salt bridge in an electrochemical cell?

A) A salt bridge provides electrical contact between the electrodes that make up the cell.
B) A salt bridge carries electrons between the cathode and anode.
C) A salt bridge insulates the two electrodes.
D) A salt bridge allows the electrolyte solution to siphon from one side of the cell to the other so the levels remain equal.
E) A salt bridge allows electrolyte to flow from one half-cell to the other in order to maintain electroneutrality.

Question 34

What is E°_cell for the following reaction? 2Fe²⁺(aq) + Cd²⁺(aq) → 2Fe³⁺(aq) + Cd(s)

A) -0.37 V
B) 0.37 V
C) -1.17 V
D) 1.17 V
E) None of these choices is correct

Question 35

Which is the correct cell notation for the following reaction? Au³⁺(aq) + Al(s) → Al³⁺(aq) + Au(s)

A) Al³⁺(aq)|Al(s)||Au³⁺(aq)|Au(s)
B) Al(s)|Al³⁺(aq)||Au³⁺(aq)|Au(s)
C) Al³⁺(aq)|Au³⁺(aq)||Al(s)|Au(s)
D) Al³⁺(aq)|Au(s)||Au³⁺(aq)|Al(s)
E) Au(s)|Al(s)||Au³⁺(aq)|Al³⁺(aq)

Question 36

A cell can be prepared from copper and tin. What is the E°_cell for the galvanic cell that forms from the following half-reactions?

A) 0.47 V
B) 0.21 V
C) -0.21 V
D) -0.47 V
E) 0.42 V

Question 37

What is the name given to the apparatus where reduction occurs in a cell where electricity flows?

A) Cathode
B) Electrode
C) Galvanic cell
D) Anode
E) Voltaic cell

Question 38

What is E°_cell for a galvanic cell represented by the combination of the following half-reactions?

A) -0.18 V
B) 0.18 V
C) 1.28 V
D) 1.66 V
E) 2.12 V

Question 39

Based on the data presented below, which is the strongest oxidizing agent?

A) [PtCl₄]^2-(aq)
B) RuO₄(s)
C) HFeO₄^-(aq)
D) H₄XeO₆(aq)
E) Cl^-(aq)

Question 40

A certain electrochemical cell has for its cell reaction: Zn + HgO → ZnO + Hg
Which is the half-reaction occurring at the anode?

A) HgO + 2e^- → Hg + O^2-
B) Zn²⁺+ 2e^- → Zn
C) Zn → Zn²⁺ + 2e^-
D) ZnO + 2e^- → Zn

Question 41

If ΔG° of the following reaction is -110 kJ/mol, what is E°_cell? (F = 96,500 C • mol ^-1) A³⁺(aq) + 3B(s) → A(s) + 3B⁺(aq)

A) +0.38 V
B) -0.09 V
C) -0.38 V
D) +0.00038 V
E) +0.09 V

Question 42

What is the equilibrium constant at 25°C for the following reaction? (R = 8.314 J/K • mol, F = 96,500 C • mol^-1)

A) 1.2 × 10⁵
B) 1.4 × 10¹⁰
C) 8.6 × 10^-6
D) 7.1 × 10^-11
E) 2.3 × 10²³

Question 43

Consider the reaction in the lead-acid cell Pb(s) + PbO₂(s) + 2H₂SO₄(aq) → 2PbSO₄(aq) + 2H₂O(l)
For which E°_cell = 2.04 V at 298 K. ΔG° for this reaction is

A) -3.94 × 10⁵ kJ/mol.
B) -3.94 × 10² kJ/mol.
C) -1.97 × 10⁵ kJ/mol.
D) -7.87 × 10² kJ/mol.
E) -7.87 × 10⁵ kJ/mol.

Question 44

What is the equilibrium constant at 25°C for the following reaction? (R = 8.314 J/K • mol, F = 96,500 C • mol^-1)

A) 4.1 × 10²⁰
B) 8.2 × 10³⁰
C) 3.3 × 10⁵¹
D) 6.7 × 10⁶¹
E) > 9.9 × 10⁹⁹

Question 45

Which equation is correct?

A) E = -(RT/nF) lnK
B) E° = (RT/nF) lnK
C) E° = (RT/nF) lnQ
D) E = -(RT/nF) lnQ
E) E = E° + lnQ

Question 46

What is the cell potential at 25°C for the following reaction if [Zn²⁺] = 1.0 × 10^{-4 M} and [Sn²⁺] = 0.20 M ? (R = 8.314 J/K • mol, F = 96,500 C • mol ^-1)

A) -0.62 V
B) +0.52 V
C) -0.52 V
D) -0.72 V
E) +0.72 V

Question 47

Given the following standard reduction potentials, calculate the solubility product of AgCN at 25°C.

A) 4.3 × 10^-14
B) 2.3 × 10¹³
C) 2.1 × 10^-14
D) 5.1 × 10¹³
E) None of these choices is correct.

Question 48

What is ΔG° for the reaction of iron(II) ions with one mole of permanganate ions? (F = 96,500 C • mol ^-1)

A) -71.4 kJ
B) -286 kJ
C) -357 kJ
D) -428 kJ
E) None of these choices is correct.

Question 49

A voltaic cell consists of a Mn/Mn²⁺ electrode (E° = -1.18 V) and a Fe/Fe²⁺ electrode (E° = -0.44 V). Calculate [Fe²⁺] if [Mn²⁺] = 0.050 M and E_cell = 0.78 V at 25°C.

A) 0.040 M
B) 0.24 M
C) 1.1 M
D) 1.8 M
E) None of these choices is correct.

Question 50

Based on the data presented below, which is the strongest reducing agent?

A) Fe³⁺
B) Fe²⁺
C) Br^-
D) Al³⁺
E) Al(s)

Question 51

What is E°_cell for the following reaction, and is it spontaneous or nonspontaneous under standard-state conditions? 2Fe³⁺(aq) + 2H₂O(l) → H₂O₂(aq) + 2H⁺(aq) + 2Fe²⁺(aq)
Given:

A) E°_cell = -1.00 V, nonspontaneous
B) E°_cell = -1.00 V, spontaneous
C) E°_cell = 1.00 V, nonspontaneous
D) E°_cell = 1.00 V, spontaneous
E) E°_cell = -0.23 V, nonspontaneous

Question 52

Which equation is correct?

A) E°_cell = E°_anode - E°_cathode
B) E°_cell = E°_cathode + E°_anode
C) E°_cell = E°_cathode - E°_anode
D) E°_cell = E°_cathode /E°_anode

Question 53

What is E°_cell for the reaction of nickel(II) ions with cadmium metal at 25°C? (R = 8.314 J/K • mol, F = 96,500 C • mol ^-1)

A) 0.0750 V
B) 0.100 V
C) 0.120 V
D) 0.150 V
E) 0.300 V

Question 54

Consider the reaction of iodine with manganese dioxide. 3I₂(s) + 2MnO₂(s) + 8OH^-(aq) 6I^-(aq) + 2MnO₄^-(aq) + 4H₂O(l)
The equilibrium constant for the overall reaction is 8.3 × 10^-7. What is E°_cell for the reaction at 25°C? (R = 8.314 J/K • mol, F = 96,500 C • mol^-1)

A) -0.36 V
B) -0.18 V
C) -0.12 V
D) -0.060 V
E) +0.12 V

Question 55

What is ΔG° at 200°C for the following reaction? (F = 96,500 C • mol ^-1) 2Na(l) + FeCl₂(s) 2NaCl(s) + Fe(s) E°_cell = 2.35 V

A) 454 kJ/mol
B) -454 kJ/mol
C) 907 kJ/mol
D) -907 kJ/mol
E) 227 kJ/mol

Question 56

Based on the data presented below, which is the strongest reducing agent?

A) Pb(s)
B) Ca(s)
C) Pt(s)
D) Br^-(aq)
E) Pt²⁺(aq)

Question 57

What is ΔG° at 298 K for the following reaction? (F = 96,500 C • mol ^-1)

A) -921 kJ/mol
B) -767 kJ/mol
C) -460 kJ/mol
D) -307 kJ/mol
E) -1840 kJ/mol

Question 58

Based on the data presented below, which is the strongest oxidizing agent?

A) Fe³⁺
B) Fe²⁺
C) Br^-
D) Al³⁺
E) Al(s)

Question 59

Which metals may be oxidized by H⁺ under standard-state conditions?

A) Ag, Cu, Sn, and Zn
B) Ag and Cu
C) Sn and Cu
D) Zn and Cu
E) Zn and Sn

Question 60

What is ΔG° for the following reaction? (F = 96,500 C • mol ^-1) I₂(s) + 2Br^-(aq) → 2I^-(aq) + Br₂(l)
Given:

A) +104 kJ/mol
B) -104 kJ/mol
C) +309 kJ/mol
D) +52 kJ/mol
E) -52 kJ/mol

Question 61

Which, if any, of the following metals would be capable of acting as a sacrificial anode when used with iron pipe?

A)
B)
C)
D)
E)

Question 62

Which metal is not capable of acting as a sacrificial anode when used with iron pipe?

A)
B)
C)
D)
E)

Question 63

What mass of nickel may be electroplated by passing a constant current of 7.2 A through a solution of NiSO₄ for 90.0 min?

A) 0.20 g Ni
B) 0.40 g Ni
C) 12 g Ni
D) 24 g Ni
E) 47 g Ni

Question 64

A metal object is to be gold-plated by an electrolytic procedure using aqueous AuCl₃ electrolyte. How much gold may be deposited in 3.0 min by a constant current of 10. A?

A) 6.2 × 10^-3 mol
B) 9.3 × 10^-3 mol
C) 1.8 × 10^-2 mol
D) 3.5 × 10^-5 mol
E) 1.6 × 10² mol

Question 65

Which is the half-reaction at the anode in a lead storage battery?

A) Pb(s) + PbO₂(s) + 4H⁺(aq) + 2SO₄^2-(aq) → 2PbSO₄(s) + 2H₂O(l)
B) PbO₂(s) + 4H⁺(aq) + 2SO₄^2-(aq) + 2e^- → PbSO₄(s) + 2H₂O(l)
C) Pb(s) + SO₄^2-(aq) → PbSO₄(s) + 2e^-
D) Pb(s) → Pb(s) + 2e^-
E) H₂(g) → 2H⁺(aq) + 2e^-

Question 66

A voltaic cell consists of a Hg/Hg₂²⁺ electrode (E°= 0.85 V) and a Sn/Sn²⁺ electrode (E°= -0.14 V). Calculate [Sn²⁺] if [Hg₂²⁺] = 0.24 M and E_cell = 1.04 V at 25°C.

A) 0.00010 M
B) 0.00070 M
C) 0.0049 M
D) 0.030 M
E) 0.050 M

Question 67

Which one of the following statements relating to the glass electrode is correct?

A) The glass electrode detects hydrogen gas.
B) The glass of a glass electrode serves to conduct electrons.
C) When pH is measured, only a single electrode, the glass electrode, need be used.
D) The potential of the glass electrode varies linearly with the pH of the solution.
E) None of these statements is correct.

Question 68

A voltaic cell consists of an Au/Au³⁺ electrode (E° = 1.50 V) and a Cu/Cu²⁺ electrode (E° = 0.34 V). Calculate [Au³⁺] if [Cu²⁺] = 1.20 M and E_cell = 1.15 V at 25°C.

A) 0.0010 M
B) 0.0020 M
C) 0.010 M
D) 0.020 M
E) 0.41 M

Question 69

How many minutes would be required to electroplate 25.0 g of chromium by passing a constant current of 4.80 A through a solution containing CrCl₃?

A) 483 min
B) 161 min
C) 322 min
D) 2.01 × 10⁴ min
E) 1.11 × 10⁴ min

Question 70

A voltaic cell consists of a Cd/Cd²⁺ electrode (E° = -0.40 V) and a Fe/Fe²⁺ electrode (E° = -0.44 V). If E_cell = 0 and the temperature is 25°C, what is the ratio [Fe²⁺]/[Cd²⁺]?

A) 2.3 × 10¹
B) 1.0 × 10¹
C) 1.0
D) 1.0 × 10^-1
E) 5.0 × 10^-2

Question 71

What mass of Cu may be deposited from a Cu²⁺ solution during electrolysis by a current of 3.00 A for 10.0 hours?

A) 63.6 g Cu
B) 35.6 g Cu
C) 6.4 g Cu
D) 3.6 g Cu
E) 71.2 g Cu

Question 72

What mass of oxygen gas is produced in the electrolysis of water, for every gram of hydrogen gas formed? Reaction: 2H₂O(l) → 2H₂(g) + O₂(g)

A) 32 g O₂
B) 16 g O₂
C) 64 g O₂
D) 20 g O₂
E) 8 g O₂

Question 73

Which is the half-reaction at the cathode in a lead storage battery?

A) Pb(s)+ PbO₂(s) + 4H⁺(aq) + 2SO₄^2-(aq) → 2PbSO₄(s) + 2H₂O(l)
B) PbO₂(s) + 4H⁺(aq) + 2SO₄^2-(aq) + 2e^- → PbSO₄(s) + 2H₂O(l)
C) Pb(s) + SO₄^2-(aq) → PbSO₄(s) + 2e^-
D) Pb(s) → Pb(s) + 2e^-
E) H₂(g) → 2H⁺(aq) + 2e^-

Question 74

Predict the products obtained from the electrolysis of a 1 M AlBr₃ solution.

A) Al and Br₂
B) Al and O₂
C) H₂ and O₂
D) H₂ and Br₂
E) Al and H₂

Question 75

What product forms at the cathode during the electrolysis of molten lithium iodide?

A) Li⁺(l)
B) Li(l)
C) I^-(l)
D) I₂(g)
E) I₃^-(l)

Question 76

What is the minimum voltage required for the electrolysis of 1.0 M NaCl in neutral solution? 2H₂O + 2Cl^- (1.0 M) → H₂(1 atm) + Cl₂(1 atm) + 2OH^-(1 × 10^{-7 M})

A) 2.19 V
B) 1.77 V
C) 0.41 V
D) -0.41 V
E) -1.78 V

Question 77

What quantity of charge is required to cause reduction of 0.20 mole of Cr³⁺ to Cr?

A) 0.60 C
B) 3.0 C
C) 1.9 × 10⁴ C
D) 5.8 × 10⁴ C
E) 9.7 × 10⁴ C

Question 78

Which is the Nernst equation?

A)
B)
C)
D)
E) None of these statements is correct.

Question 79

How much charge must pass through an electrolytic cell to reduce 0.44 mol Ca²⁺ ion to calcium metal?

A) 1.9 ×10⁵ C
B) 8.5 ×10⁴ C
C) 2.1 ×10⁴ C
D) 4.3 ×10⁴ C
E) 0.88 C

Question 80

What is the half-reaction that occurs at the cathode during the electrolysis of an aqueous sodium iodide solution?

A) Na⁺ + e^- →
B) O₂(g) + 4H⁺(aq) + 4e^- → 2H₂O(l)
C) 2H₂O + 2e^- → H₂ + 2OH^-
D) I₂ + 2e^- → 2I^-
E) 2I^- → I₂ + 2e^-