Deck 20: Electrochemistry

Question 1

Cathodic protection is attaching a more active metal to the protected metal.

Answer 1

True

Question 2

Choose the INCORRECT statement.

A) When a half reaction is reversed, the sign of the potential is changed.
B) Reversing a half reaction makes it a reduction potential.
C) Each electrochemical cell consists of a reduction half cell and an oxidation half cell.
D) A voltaic cell is also called a battery.
E) The potential difference of a cell is the voltage of the cell.

Answer 2

Reversing a half reaction makes it a reduction potential.

Question 3

The active metal is called a sacrificial cathode.

Answer 3

False

Question 4

Choose the INCORRECT statement.

A) A double vertical line separates half cells in a cell diagram.
B) A single vertical line separates phases in a cell diagram.
C) A voltaic cell is a galvanic cell.
D) Voltaic cells produce an electron flow.
E) Electrolytic cells are cells where electron flow is caused by spontaneous reactions.

Question 5

In a galvanic cell, oxidation occurs at the cathode.

Question 6

When Ecell < 0, the reaction is spontaneous.

Question 7

A primary battery is recharged by passing electricity through the battery.

Question 8

Corrosion of metals is an oxidation-reduction process.

Question 9

Primary batteries' cell reactions cannot be reversed.

Question 10

In the electrolysis of water, oxygen is evolved at the cathode.

Question 11

Choose the INCORRECT statement.

A) An electrode is often a strip of metal.
B) An electrode in a solution of its ions is a half cell.
C) An electrochemical cell is a half cell.
D) The electromotive force (emf) is the cell potential.
E) The cell potential is the potential difference between the half cells.

Question 12

Choose the INCORRECT statement.

A) SHE stands for Standard Helium Electrodes.
B) E° is the standard electrode potential.
C) The standard electrode potential is the reduction potential of a half cell.
D) The standard cell potential is the potential difference between two half cells.
E) E°cell is the standard cell potential.

Question 13

In a galvanic cell, oxidation occurs at the:

A) anode
B) cathode
C) salt bridge
D) electrolyte
E) in cathodic space

Question 14

Choose the INCORRECT statement.

A) Electrons are transferred in oxidation-reduction reactions.
B) A strip of metal in a solution of ions of that metal is an electrode potential.
C) Reduction is the gain of electrons.
D) Oxidation is the loss if electrons.
E) A salt bridge maintains electrical contact between two half cells.

Question 15

In a zinc-lead cell the reaction is: Pb2+ + Zn → Pb + Zn2+ E° = 0.637 V
Which of the following statements about this cell is FALSE?

A) The zinc electrode is the cathode.
B) The reaction will go in the direction indicated.
C) The shorthand notation is Zn ∣ Zn2+  Pb2+ ∣ Pb
D) The actual cell voltage is less than +0.637 volts because of concentration polarization and possible other factors.
E) The lead electrode is positively charged.

Question 16

E°cell is the standard cell potential.

Question 17

Choose the correct statement based on the following oxidation potentials. Mg/Mg2+ +2.37 v Fe/Fe2+ +0.44 v Cu/Cu2+ -0.34 v
Zn/Zn2+ +0.76 v Sn/Sn2+ +0.14 v Ag/Ag+ -0.80 v

A) Mg will not displace Zn2+ from solution
B) Cu will displace Sn2+ from solution
C) Fe will displace Zn2+ from solution
D) Fe will displace H+ from solution
E) Sn will displace Fe2+ from solution

Question 18

The hydrogen standard electrode is the most convenient standard electrode to use.

Question 19

The Ecell for the following concentration cell at 25°C is 0.006.
Pt ∣ H2 (g, 0.025 atm) ∣ H+ (0.012 M)  H+ (1 M) ∣ H2 (g, 1 atm) ∣ Pt
2 H+(aq) + 2 e- → H2(g) E° = 0. V

Question 20

Choose the INCORRECT statement.

A) A cell diagram is a symbolic way to show cell components.
B) An anode is where oxidation occurs.
C) A cathode is where reduction occurs.
D) Half cells in a cell diagram are separated by a single vertical line.
E) The anode is on the left in a cell diagram.

Question 21

Choose the INCORRECT statement.

A) A concentration cell consists of half cells with identical electrodes but different ion concentrations.
B) Primary batteries' cell reactions cannot be reversed.
C) Secondary batteries' cell reaction can be reversed.
D) A primary battery is recharged by passing electricity through the battery.
E) Cells can be joined in series to increase the total voltage.

Question 22

Determine E°cell for the reaction: Pb2+ + Zn → Pb + Zn2+. The half reactions are: Pb2+(aq) + 2 e- → Pb(s) E° = -0.125 V
Zn2+(aq) + 2 e- → Zn(s) E° = -0.763 V

A) 0.638 V
B) -0.638 V
C) 0.888 V
D) -1.276 V
E) -0.888 V

Question 23

Calculate the Ksp of lead iodide from the following standard electrode potentials, at 25°C: 2 e- + PbI2(S) → Pb(s) + 2 I-(aq) E° = -0.365 V
2 e- + Pb2+(aq) → Pb(s) E° = -0.126 V

A) 8 × 10-9
B) 9 × 10-5
C) 2 × 10-17
D) 5 × 10-13
E) 6 × 10-5

Question 24

If the voltage of an electrochemical cell is negative then the cell reaction is:

A) nonspontaneous
B) slow
C) exothermic
D) spontaneous
E) fast

Question 25

Choose the INCORRECT statement.

A) One mole of hydrogen ions will have a positive charge of one Faraday.
B) One Faraday of charge will release 35.5 g of Cl2 in the electrolysis of a chloride solution.
C) One Faraday of charge will plate out two moles of Cu from a solution of CuSO4(aq).
D) One mole of electrons has a charge of l Faraday.
E) One mole of hydrogen gas requires 2 Faradays.

Question 26

For the reaction: Mg(s) + AgNO3(aq) → Ag(s) + Mg(NO3)2(aq) Ag+(aq) + e- → Ag(s) E° = 0.800 V
Mg2+(aq) + 2 e- → Mg(s) E° = -2.356 V
Is the reaction spontaneous and why?

A) No, Mg(s) does not react with Ag+.
B) No, E° is a positive value.
C) No, E° is a negative value.
D) Yes, E° is a positive value.
E) Yes, E° is a negative value.

Question 27

What is the concentration of Al3+ in the following cell at 25°C if the cell voltage is 1.486 V? Al ∣ Al3+(?)  Sn2+(3.21 × 10-4 M) ∣ Sn
Al3+ + 3 e- → Al(s) E° = -1.676 V
Sn2+ + 2 e- → Sn(s) E° = -0.137 V

A) 2.8 × 10-3 M
B) 1.6 × 10-5 M
C) 4.5 × 10-5 M
D) 2.4 × 10-2 M
E) 7.8 × 10-6 M

Question 28

Glass electrodes are used for direct measurement of:

A) pH
B) pKa
C) Ksp
D) Q
E) pKw

Question 29

Consider the cell: Ni ∣ Ni2+ (?M)  Cu2+ (0.136 M) ∣ Cu
Ni2+/Ni E° = -0.257 V
Cu2+/Cu E° = 0.340 V
The measured potential of the cell is 0.621 V. What is [Ni2+] at 25°C?

A) 2 × 10-2 M
B) 1 M
C) 4 × 10-42 M
D) 0.05 M
E) 0.4 M

Question 30

The lithium-ion battery is based on:

A) Li+/Li couple
B) Co3+/Co2+ couple
C) Co(III)/Co(IV) couple
D) both Li+/Li and Co3+/Co2+
E) both Li+/Li and Co(III)/Co(IV)

Question 31

Choose the INCORRECT statement.

A) Corrosion of metals is an oxidation reduction process.
B) Rust is a form of corrosion.
C) Metals can be protected by cathodic protection.
D) Cathodic protection is attaching a more active metal to the protected metal.
E) The active metal is called a sacrificial cathode.

Question 32

What is the cell diagram for the spontaneous cell involving the Fe3+ ∣ Fe2+ (0.771V) half cell and the Zn2+ ∣ Zn (-0.763 V) half cell?

A) Fe2+(aq) ∣ Fe3+(aq)  Zn2+(aq) ∣ Zn(s)
B) Pt(s) ∣ Fe2+(aq), Fe3+(aq)  Zn2+(aq) ∣ Zn(s)
C) Zn(s) ∣ Zn2+(aq)  Fe3+(aq) ∣ Fe2+(aq) ∣ Pt(s)
D) Zn(s) ∣ Zn2+(aq)  Fe3+(aq) ∣ Fe2+(aq)
E) Zn(s) ∣ Zn2+(aq)  Fe3+(aq) ∣ Fe2+(aq) ∣ Zn(s)

Question 33

In the cell Fe2+ ∣ Fe3+  Cu2+ ∣ Cu which will increase the cell voltage the most?

A) Halve [Cu2+].
B) Halve [Fe2+].
C) Double [Cu2+].
D) Double [Fe2+].
E) Cut Cu electrode in half.

Question 34

Which of the following are commonly used as alternate standard electrodes:
I. Ag(s) | AgCl(s) | Cl- (1.0 M)
II. Hg(l) | HgCl2(s) | Cl- (1.0 M)
III. Ag(s) | AgCl(s) | Cl- (0.1 M)
IV. Hg(l) | Hg2Cl2(s) | Cl- (1.0 M)
V. Hg(s) | Hg2Cl2(s) | Cl- (1.0 M)

A) I) and V)
B) II) and IV)
C) I) and IV)
D) II) and III)
E) I) and III)

Question 35

Determine E°cell for the reaction: 2 Al + 3 Zn2+ → 2 Al3+ + 3 Zn. The half reactions are: Al3+(aq) + 3 e- → Al(s) E° = -1.676 V
Zn2+(aq) + 2 e- → Zn(s) E° = -0.763 V

A) 0.913 V
B) -2.439 V
C) 2.439 V
D) -1.063 V
E) -0.913 V

Question 36

What is the concentration of Cu2+ in the following cell at 25°C if the cell voltage is 1.253 V? Zn ∣ Zn2+ (0.125 M)  Cu2+(?) ∣ Cu
Cu2+ + 2 e- → Cu(s) E° = 0.340 V
Zn2+ + 2 e- → Zn(s) E° = -0.763 V

A) 0.6 M
B) 1 × 10-2 M
C) 1 × 10-6 M
D) 9 × 10-4 M
E) 4 × 10-4 M

Question 37

Determine E°cell for the reaction: 2 Ag+ + Mg → 2 Ag + Mg2+. The half reactions are: Mg2+(aq) + 2 e- → Mg(s) E° = -2.356 V
Ag+(aq) + e- → Ag(s) E° = 0.800 V

A) 0.756 V
B) -0.756 V
C) 3.156 V
D) -1.556 V
E) 1.556 V

Question 38

Choose the INCORRECT statement.

A) The work available in a cell = -zFEcell.
B) ΔG° = -zFE°cell
C) When Ecell < 0, the reaction is spontaneous.
D) When Ecell = 0, the reaction is at equilibrium.
E) Reversing a cell reaction changes the sign of Ecell.

Question 39

Determine the Ksp at 25°C of AgCl(s). The half-reactions are: Ag+(aq) + 1 e- → Ag(s) E° = +0.771 V
AgCl(s) + 1 e- → Ag(s) + Cl- E° = +0.222 V

A) 1 × 10-2
B) 0.771
C) 4 × 1011
D) 5 × 10-10
E) 4 × 10-11

Question 40

For the reaction: Mg(s) + AgNO3(aq) → Ag(s) + Mg(NO3)2(aq) Ag+(aq) + e- → Ag(s) E° = 0.800 V
Mg2+(aq) + 2 e- → Mg(s) E° = -2.356 V
Estimate Keq at 25°C.

A) 5.7 × 10106
B) 2.0 × 1053
C) 3.7 × 1052
D) 1.1 × 1027
E) 10-107

Question 41

Determine E°cell for the reaction: I2 + Cu → 2 I- + Cu2+. The half reactions are: I2(s) + 2 e- → 2 I-(aq) E° = +0.535 V
Cu2+ + 2 e- → Cu E° = 0.340 V

A) 0.730 V
B) -0.875 V
C) 0.875 V
D) 0.195 V
E) -0.195 V

Question 42

The following half-reactions are used in the zinc-air battery. Zn(OH)42- (aq) + 2 e- → Zn(s) + 4 OH-(aq) E° = -1.199 V
O2(g) + 2 H2O(l) + 4 e- → 4 OH-(aq) E° = +0.401 V
How much charge is transferred per gram Zn(s) in this voltaic cell?

A) 5.90 × 103 C
B) 2.95 × 103 C
C) 1.47 × 103 C
D) 3.39 × 10-4 C
E) 1.69 × 10-4 C

Question 43

An electrolysis is carried out by passing an electric current through a solution of copper sulfate using inert electrodes. This causes:

A) Cu to plate out on the negative electrode
B) Cu to plate out on the anode
C) oxygen to form on the negative electrode
D) H2 to form at the negative electrode
E) sulfur to form on the positive electrode

Question 44

Determine E°cell at 25°C for the following reaction: 3 Sn2+ + 2 Al(s) → 2 Al3+ + 3 Sn(s)
Al3+ + 3 e- → Al(s) E° = -1.676 V
Sn2+ + 2 e- → Sn(s) E° = -0.137 V

A) 2.941 V
B) -1.813 V
C) 1.813 V
D) -1.539 V
E) 1.539 V

Question 45

Determine E°cell for the reaction: Pb + Cu2+ → Pb2+ + Cu. The half reactions are: Pb2+(aq) + 2 e- → Pb(s) E° = -0.125 V
Cu2+ + 2 e- → Cu E° = 0.340 V

A) 0.215 V
B) 0.465 V
C) 0.930 V
D) -0.215 V
E) -0.465 V

Question 46

One mole of electrons has a charge of:

A) 96,485 A
B) 1.60 × 10-19
C) 6.02 × 1023 A
D) 96,485 C
E) 96,485 F

Question 47

Write the net redox reaction that occurs in the following galvanic cell. Ti(s) ∣ Ti3+(aq)  Se2-(aq) ∣ Se(s)

A) Ti(s) + Se2-(aq) + 1 e- → Ti3+(aq) + Se(s)
B) 2 Ti(s) + 3 Se(s) → 2 Ti3+(aq) + 3 Se2-(aq)
C) Ti(s) + Se(s) → Ti3+(aq) + Se2-(aq) + 1 e-
D) 2 Ti3+(aq) + 3 Se(s) → 2 Ti(s) + 3 Se2-(aq)
E) 2 Ti3+(aq) + 3 Se(s) + 1 e- → 2 Ti(s) + 3 Se2-(aq)

Question 48

For the reaction: Mg(s) + 2 AgNO3(aq) → 2 Ag(s) + Mg(NO3)2(aq) Write a voltaic diagram for the reaction.

A) Ag(s) | Ag(aq)  Mg2+(aq) | Mg(s)
B) Mg(s) ∣ Mg2+  Ag+ (aq) ∣ Ag (s)
C) Mg(s) ∣ Mg2+  Ag(s) ∣ Ag+ (aq)
D) Ag(aq) ∣ Ag(s)  Mg(s) ∣ Mg2+ (aq)
E) Ag(s) ∣ Mg2+ (aq)  Ag+ (aq) ∣ Mg(s)

Question 49

How many coulombs would be needed to deposit all of the Ag+ ion from 600 mL of a solution 0.250 M in Ag+?

A) 1.45 × 107 C
B) 1.56 × 106 C
C) 1.45 × 104 C
D) 2.41 × 104 C
E) 1.56 × 104 C

Question 50

Given the table below predict the numerical value of the standard cell potential for the reaction: 2 Cr(s) + 3 Cu2+(aq) → 2 Cr3+(aq) + 3 Cu(s)
Half Reaction E° (volts)
(1) Cr3+ + 3 e- → Cr -0.74
(2) Cr3+ + e- → Cr2+ -0.41
(3) Cr2O72- + 14 H+ + 6 e- → 2 Cr3+ + 7 H2O 1.33
(4) Cu+ + e- → Cu 0.52
(5) Cu2+ + 2 e- → Cu 0.34
(6) Cu2+ + e- → Cu+ 0.16

A) 2.50 volts
B) 0.417 volts
C) -1.08 volts
D) 1.08 volts
E) -0.40 volts

Question 51

Write the net redox reaction that occurs in the galvanic cell. Zn(s) ∣ Zn+2(aq)  Pb+2(aq)∣Pb(s)

A) Pb(s) + Zn(s) → Pb+2(aq) + Zn+2(aq) + 4 e-
B) Pb(s) + Zn+2(aq) → Pb+2(aq) + Zn(s)
C) Pb+2(s) + Zn+2(s) → Pb(s) + Zn(s) + 4 e-
D) Pb+2(aq) + Zn(s) → Zn+2(aq) + Pb(s)
E) Pb(s) + Zn(s) + 4 e- → Pb+2(aq) + Zn+2(aq)

Question 52

Will magnesium metal displace Al3+ ion from an aqueous solution? Mg2+(aq) + 2 e- → Mg(s) E° = -2.356 V
Al3+(aq) + 3 e- → Al(s) E° = -1.676 V

A) No, since E°cell is negative.
B) Yes, since E°cell is negative.
C) No, the reverse reaction is spontaneous.
D) Yes, since E°cell is positive.
E) No, the system is at equilibrium.

Question 53

Determine E°cell for the reaction: Cl2 + 2 F- → 2 Cl- + F2. The half reactions are: F2(s) + 2 e- → 2 F-(aq) E° = +2.866 V
Cl2(s) + 2 e- → 2 Cl-(aq) E° = 1.358 V

A) 3.016 V
B) -4.224 V
C) 1.508 V
D) 4.224 V
E) -1.508 V

Question 54

Determine E°cell for the reaction: 2 Ag + Mg2+ → 2 Ag+ + Mg. The half reactions are: Mg2+(aq) + 2 e- → Mg(s) E° = -2.356 V
Ag+(aq) + e- → Ag(s) E° = 0.800 V

A) 0.756 V
B) -0.756 V
C) 3.156 V
D) -3.156 V
E) 1.556 V

Question 55

For the reaction: Mg(s) + AgNO3(aq) → Ag(s) + Mg(NO3)2(aq) Ag+(aq) + e- → Ag(s) E° = 0.800 V
Mg2+(aq) + 2 e- → Mg(s) E° = -2.356 V
For the reaction, determine E° for the cell.

A) 1.556 V
B) -3.156 V
C) 3.156 V
D) 0.800 V
E) 2.356 V

Question 56

Determine E°cell at 25 °C for the following reaction: Pb2+(aq) + Cu(s) → Cu2+(aq) + Pb(s)
The half-reactions are:
Pb2+(aq) + 2 e- → Pb(s) E° = -0.125 V
Cu2+(aq) + 2 e- → Cu(s) E° = +0.337 V

A) 0.212 V
B) -0.462 V
C) 0.462 V
D) -0.212 V
E) 0.424 V

Question 57

Choose the INCORRECT completion of the following sentence: "In the electrolysis of water...

A) ...a direct current must be used."
B) ...oxygen is evolved at the cathode."
C) ...electrical energy must be supplied continuously because it is an endothermic reaction."
D) ...the volume of hydrogen produced is twice the volume of oxygen produced."
E) ....one mole of H₂ is produced for each two moles of electrons."

Question 58

Determine E°cell for the reaction: MnO4- + 8 H+ + 5 Fe2+ → Mn2+ + 4 H2O + 5 Fe3+. The half reactions are: Fe3+(aq) + e- → Fe2+(aq) E° = +0.771 V
MnO4-(aq) + 8 H+(aq) + 5 e- → Mn2+(aq) + 4 H2O(l) E° = 1.507 V

A) -2.34 V
B) -2.28 V
C) 2.28 V
D) -0.74 V
E) 0.74 V

Question 59

Determine E°cell for the reaction: 2 Al3+ + 3 Zn → 2 Al + 3 Zn2+. The half reactions are: Al3+(aq) + 3 e- → Al(s) E° = -1.676 V
Zn2+(aq) + 2 e- → Zn(s) E° = -0.763 V

A) 0.913 V
B) -2.439 V
C) 2.439 V
D) -1.063 V
E) -0.913 V

Question 60

Determine E°cell for the reaction: Pb + Zn2+ → Pb2+ + Zn. The half reactions are: Pb2+(aq) + 2 e- → Pb(s) E° = -0.125 V
Zn2+(aq) + 2 e- → Zn(s) E° = -0.763 V

A) 0.638 V
B) -0.638 V
C) 0.888 V
D) -1.276 V
E) -0.888 V

Question 61

The standard Gibbs energy change for the following voltaic cell is ΔG° = -89.3 kJ at 25°C. What is E°cell? Cu(s) | Cu2+(aq) || Ag+(aq) | Ag(s)

A) +0.463 V
B) -0.926 V
C) -0.463 V
D) +0.926 V
E) +0.231 V

Question 62

The net reaction in a voltaic cell with E°cell = +0.726 V is, 2 Fe3+(aq) + 3 Zn(S) → 2 Fe(s) + 3 Zn2+(aq)
What is ΔG° for this reaction at 25°C?

A) -210 kJ
B) -140 kJ
C) -700 kJ
D) -463 kJ
E) -420 kJ

Question 63

What is Keq at 25°C of the spontaneous cell made from the Zn2+/Zn (-0.76 V) and Br2/2Br- (1.07 V) half cells?

A) 10-6
B) 105
C) 1010
D) 10-11
E) 1061

Question 64

Find Ecell for the following voltaic cell at 25°C: Ti(s) ∣ Ti2+(aq) (0.550M)  Sn2+(aq) (0.005 M) ∣ Sn(s)
The half-reactions are:
Ti2+(aq) + 2 e- ⇔ Ti(s) E° = -1.630 V
Sn2+(aq) + 2 e- ⇔ Sn(s) E° = -0.137 V

A) 1.372 V
B) 1.707 V
C) 1.646 V
D) 1.433 V
E) -1.646 V

Question 65

Using the following reduction half-reactions and their respective standard reduction potentials at 25°C, draw a diagram of a galvanic cell. Cr2O72-(aq) + 14 H+(aq) + 6e- → 2 Cr3+(aq) + 7 H2O E° = +1.33 V
Zn2+(aq) + 2 e- → Zn(s) E° = -0.763 V

A) Zn2+(aq) ∣ Zn(s), H+(aq)  Cr2O72-(aq), Cr(s) ∣ Cr3+(aq)
B) Zn(s) ∣ Zn2+(aq)  H+(aq), Cr3+(aq) ∣ Cr(s)
C) Cr(s) ∣ Cr3+(aq), H+(aq), Cr2O72-(aq)  Zn(S) ∣ Zn2+(aq)
D) Zn(s) ∣ Zn2+(aq)  Cr2O72-(aq), H+(aq), Cr3+(aq) ∣ Pt(s)
E) Pt(s) ∣ Cr3+(aq), Cr2O72-(aq), H+(aq)  Zn2+(aq) ∣ Zn(s)

Question 66

What is the standard cell potential if the Gibbs energy is -2108 kJ in the reaction: C3H8 + O2(g) → CO2(g) + H2O(l) (not balanced)?

A) -10.92 V
B) 10.92 V
C) 21.85 V
D) -1.092 V
E) 1.092 V

Question 67

Calculate Ecell at 25°C for the following voltaic cell. Ksp for NiCO3 is 1.42 × 10-7. Ni(s) ∣ Ni2+(aq) [sat'd NiCO3(s)]  Ni2+(aq) (0.010M) ∣ Ni(s)
The half-reaction is: Ni2+(aq) + 2 e- → Ni(s) E° = -0.257 V

A) +0.257 V
B) -0.257 V
C) 0.000 V
D) +0.0844 V
E) +0.0422 V

Question 68

What is the cell reaction of the spontaneous cell made from the Zn2+/Zn (-0.76 V) and Br2 /2Br-(1.07 V) half cells?

A) 2 Br- + Zn2+ → Zn + Br2
B) Br2 + Zn → Zn2+ + 2 Br-
C) 2 Br- + Zn → Br2 + Zn2+
D) Br2 + Zn → Zn2+ + Br-
E) Br2 + Zn2+ → Zn + 2Br-

Question 69

What is ΔG° at 25°C for the reaction (not balanced): C3H8 + O2(g) → CO2(g) + H2O(l) if the standard cell potential is 1.092 V?

A) -105 kJ
B) -211 kJ
C) 105 kJ
D) -2107 kJ
E) 211 kJ

Question 70

What is E° of the spontaneous cell made from Ag+/Ag (0.80 V) and Cl2/Cl- (1.36 V) half cells?

A) 2.16 V
B) -2.16 V
C) -0.56 V
D) 0.56 V
E) 1.36 V

Question 71

What is E° of the spontaneous cell made from the Zn2+/Zn (-0.76 V) and Br2/2Br- (1.07 V) half cells?

A) -1.83 V
B) 0.31 V
C) 1.83 V
D) -0.31 V
E) -0.76 V

Question 72

Determine Ecell at 25°C for the following reaction at 25°C: Al ∣ Al3+(0.435 M)  Sn2+(2.12 × 10-3 M) ∣ Sn
3 Sn2+ + 2 Al(s) → 2 Al3+ + 3 Sn(s)
Al3+ + 3 e- → Al(s) E° = -1.676 V
Sn2+ + 2 e- → Sn(s) E° = -0.137 V

A) 1.227 V
B) 1.611 V
C) 1.562 V
D) 1.487 V
E) 1.467 V

Question 73

The following galvanic cell has a measured cell potential E°cell = 0.646 V. Pt(s) ∣ Sn4+(aq), Sn2+(aq)  Ag+(aq) ∣ Ag(s)
Given that the standard reduction potential for the reduction of Ag+ to Ag(s) is +0.800 V, what is the standard reduction potential for the Sn4+/Sn2+ half-reaction?

A) +0.154 V
B) -0.154 V
C) +1.45 V
D) -1.45 V
E) +0.308 V

Question 74

What is the cell diagram for the spontaneous cell involving the Cl2 ∣ Cl- (1.358 V) and the Sn2+ ∣ Sn (-0.137V) half cells?

A) Pt ∣ Cl2(g) ∣ Cl-(aq)  Sn2+(aq) ∣ Sn(s)
B) Sn(S) ∣ Sn2+(aq)  Cl-(aq) ∣ Cl2(g) ∣ Pt
C) Cl2(g) ∣ Cl-(aq)  Sn2+(aq) ∣ Sn(s)
D) Sn(S)  Sn2+(aq)  Cl-(aq) ∣ Cl2(g)
E) Sn(S) ∣ Cl-(aq)  Sn2+(aq) ∣ Sn(s)

Question 75

Determine Keq at 25°C for the following reaction: Pb2+(aq) + Cu(s) ⇔ Cu2+(aq) + Pb(s)
The half-reactions are:
Pb2+(aq) + 2 e- ⇔ Pb(s) E° = -0.125 V
Cu2+(aq) + 2 e- ⇔ Cu(s) E° = +0.337 V

A) 2 × 1069
B) 2 × 10-16
C) 2 × 1016
D) 2 × 10-8
E) 6 × 107

Question 76

What is Keq at 25°C of the spontaneous cell made from Ag+/Ag (0.80 V) and Cl2/Cl- (1.36 V) half cells?

A) 1073
B) 10-10
C) 109
D) 1019
E) 10-19

Question 77

Zn+2(aq) + 2 e- → Zn(s) E° = -0.763 V

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

Question 78

What is Ecell at 25°C of the spontaneous cell made from Ag+/Ag (0.80 V) and Cl2/Cl- (1.36 V) half cells if [Ag+] = 10-2 and [Cl-] = 10-4 with P(Cl2) = 1.1 atm?

A) 0.65 V
B) 0.38 V
C) 0.74 V
D) 0.92 V
E) 0.20 V

Question 79

For the cell reaction at 25°C Cu2+(aq) + Zn(s) → Cu(s) + Zn2+(aq), E°cell = +1.100 V. What is the equilibrium constant for this reaction?

A) 3 × 10-19
B) 2 × 1037
C) 2 × 10-37
D) 3 × 1018
E) 3 × 10-18

Question 80

For the reaction: Mg(s) + AgNO3(aq) → Ag(s) + Mg(NO3)2(aq) Ag+(aq) + e- → Ag(s) E° = 0.800 V
Mg2+(aq) + 2 e- → Mg(s) E° = -2.356 V
Determine ΔG°.

A) -300.3 kJ/mol
B) 304.5 kJ/mol
C) 609.0 kJ/mol
D) -304.5 kJ/mol
E) -609.0 kJ/mol