Deck 21: Electrochemistry: Chemical Change and Electrical Work

Question 1

In the electrolyte of an electrochemical cell, current is carried by anions moving toward the anode and cations moving in the opposite direction.

Answer 1

True

Question 2

Electrolytic cells utilize electrical energy to drive nonspontaneous redox reactions.

Answer 2

True

Question 3

A buried iron pipe can be protected against corrosion by connecting it to a rod of copper.

Answer 3

False

Question 4

The lead-acid battery is an example of a secondary battery.

Question 5

Oxidation occurs at the cathode of a galvanic cell, but at the anode of an electrolytic cell.

Question 6

Consider the following balanced redox reaction Mn²⁺(aq) + S₂O₈²⁻(aq) + 2H₂O(l) → MnO₂(s) + 4H(aq) + 2SO₄²⁻(aq)
Which of the following statements is true?

A)Mn ²⁺( aq)is the oxidizing agent and is reduced.
B)Mn ²⁺( aq)is the oxidizing agent and is oxidized.
C)Mn ²⁺( aq)is the reducing agent and is oxidized.
D)Mn ²⁺( aq)is the reducing agent and is reduced.
E)Manganese does not change its oxidation number in this reaction.

Question 7

For the reaction occurring in a voltaic (galvanic) cell, ΔG > 0.

Question 8

A primary battery is one that can be recharged.

Question 9

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

A)CuO and H ₂
B)H ₂ and CuO
C)CuO and Cu
D)H ₂O and H ₂
E)None of these choices are correct.

Question 10

A salt bridge provides a path for electrons to move between the anode and cathode compartments of a voltaic cell.

Question 11

In the shorthand notation for cells, a double vertical line is used to separate the reduced and oxidized forms of a redox couple.

Question 12

In the electrolyte of an electrochemical cell, current is carried by electrons moving from the anode to the cathode.

Question 13

In the absence of oxygen, iron will rust as long as moisture is present.

Question 14

In the shorthand notation for cells, a single vertical line represents a salt bridge.

Question 15

In a fuel cell, an external source of electrical power is used to drive a nonspontaneous reaction in which a fuel is produced.

Question 16

A buried iron pipe can be protected against corrosion by connecting it to a rod of magnesium.

Question 17

A secondary cell (battery) can operate either as a galvanic or an electrolytic cell.

Question 18

If the electrodes of a voltaic cell are connected with an external wire, electrons will flow in this wire from the cathode to the anode.

Question 19

Which one of the following is not a redox reaction?

A)Al(OH)₄( aq)+ 4H( aq)→ Al ³+( aq)+ 4H ₂O( l)
B)C ₆H ₁₂O ₆( s)+ 6O ₂( g)→ 6CO ₂( g)+ 6H ₂O( l)
C)Na ₆FeCl ₈( s)+ 2Na( l)→ 8NaCl( s)+ Fe( s)
D)2H ₂O ₂( aq)→ 2H ₂O( l)+ O ₂( g)
E)CO ₂( g)+ H ₂( g)→ CO( g)+ H ₂O( g)

Question 20

Electrons are produced at the cathode of a voltaic cell.

Question 21

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

A)Al( s)→ Al ³⁺( aq)+ 3e ⁻
B)Al ³⁺( aq)+ 3e → Al( s)
C)Ni( s)→ Ni ²⁺( aq)+ 2e ⁻
D)Ni ²⁺( aq)+ 2e ⁻ → Ni( s)
E)None of these choices are correct.

Question 22

Which one of the following statements about electrochemical cells is correct?

A)In a salt bridge, current is carried by cations moving toward the anode, and anions toward the cathode.
B)In the external wire, electrons travel from cathode to anode.
C)The anode of a voltaic cell is labeled minus (−).
D)Oxidation occurs at the cathode, in an electrolytic cell.
E)None of these choices are correct.

Question 23

A voltaic cell prepared using zinc and iodine has the following cell notation. Zn(s) | Zn²⁺(aq) || I⁻(aq) | I₂(s) | C(graphite)
Which of the following equations correctly represents the balanced, spontaneous, cell reaction?

A)2I ⁻( aq)+ Zn ²⁺( aq)→ I ₂( s)+ Zn( s)
B)I ₂( s)+ Zn( s)→ 2I ⁻( aq)+ Zn ²⁺( aq)
C)2I ⁻( aq)+ Zn( s)→ I ₂( s)+ Zn ²⁺( aq)
D)I ₂( s)+ Zn ²⁺( aq)→ 2I ⁻( aq)+ Zn( s)
E)None of these choices are correct.

Question 24

Which of the following solids is commonly used as an inactive electrode in electrochemical cells?

A)Zinc
B)Graphite
C)Copper
D)Iron
E)Sodium

Question 25

The line notation, Pt | H₂(g) | H⁺(aq) || Cu²⁺(aq) | Cu(s), indicates that

A)copper metal is a product of the cell reaction.
B)hydrogen gas (H ₂)is a product of the cell reaction.
C)Cu is the anode.
D)Pt is the cathode.
E)Cu ²⁺ is the reducing agent.

Question 26

When the following redox equation is balanced with smallest whole number coefficients, the coefficient for Sn(OH)₃⁻ will be Bi(OH)₃(s) + Sn(OH)₃(aq) → Sn(OH)₆²⁻(aq) + Bi(s) (basic solution)

A)1.
B)2.
C)3.
D)6.
E)None of these choices are correct.

Question 27

Which of the following statements about voltaic and electrolytic cells is correct?

A)The anode will definitely gain weight in a voltaic cell.
B)Oxidation occurs at the cathode of both cells.
C)The free energy change, Δ G, is negative for the voltaic cell.
D)The electrons in the external wire flow from cathode to anode in an electrolytic cell.
E)None of these choices are correct.

Question 28

A voltaic cell can be prepared from copper and tin. What is the E°_cell for the cell that forms from the following half-reactions? Cu²⁺(aq) + 2e⁻ ⇄ Cu(s) E° = 0.34 V
Sn⁴⁺(aq) + 2e⁻ ⇄ Sn²⁺(aq) E° = 0.13 V

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

Question 29

The line notation, Al(s) | Al³⁺(aq) || Co²⁺(aq) | Co(s), indicates that

A)Co is the reducing agent.
B)Co ²⁺ ions are oxidized.
C)Al is the reducing agent.
D)Al ³⁺ is the reducing agent.
E)aluminum metal is the cathode.

Question 30

Consider the following redox equation Mn(OH)₂(s) + MnO₄(aq) → MnO₄²⁻(aq) (basic solution)
When the equation is balanced with 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)None of these choices are correct.

Question 31

Which one of the following pairs of substances could be used to construct a single redox electrode (i.e., they have an element in common, but in different oxidation states)?

A)HCl and Cl ⁻
B)H ⁺ and OH ⁻
C)H ₂O and H ⁺
D)Fe ³⁺ and Fe ₂O ₃
E)MnO ₂ and Mn ²⁺

Question 32

When the following redox equation is balanced with smallest whole number coefficients, the coefficient for the iodide ion will be I⁻(aq) + NO₃⁻(aq) → NO(g) + I₂(s) (acidic solution)

A)2.
B)3.
C)6.
D)8.
E)None of these choices are correct.

Question 33

When the following redox equation is balanced with smallest whole number coefficients, the coefficient for zinc will be Zn(s) + ReO₄(aq) → Re(s) + Zn²⁺(aq) (acidic solution)

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

Question 34

When the following redox equation is balanced with smallest whole number coefficients, the coefficient for the hydrogen sulfate ion will be Al(s) + HSO₄(aq) + OH⁻(aq) → Al₂O₃(s) + S²⁻(aq) + H₂O(l)

A)1.
B)3.
C)4.
D)8.
E)None of these choices are correct.

Question 35

A voltaic cell prepared using aluminum and nickel has the following cell notation. Al(s) | Al³⁺(aq) || Ni²⁺(aq) | Ni(s)
Which of the following represents the correctly balanced spontaneous reaction equation for the cell?

A)Ni ²⁺( aq)+ Al( s)→ Al ³⁺( aq)+ Ni( s)
B)3Ni ²⁺( aq)+ 2Al( s)→ 2Al ³⁺( aq)+ 3Ni( s)
C)Ni( s)+ Al ³⁺( aq)→ Ni ²⁺( aq)+ Al( s)
D)3Ni( s)+ 2Al ³⁺( aq)→ 3Ni ²⁺( aq)+ 2Al( s)
E)None of these choices are correct.

Question 36

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

A)1
B)2
C)4
D)10
E)None of these choices are correct.

Question 37

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 N ₂( g)is the reducing agent.

Question 38

Which component of the following cell notation is the anode? P | Q || R | S

A)P
B)Q
C)R
D)S
E)One of the | symbols is the anode.

Question 39

Which of the following statements about voltaic and electrolytic cells is correct?

A)The electrons in the external wire flow from cathode to anode in both types of cell.
B)Oxidation occurs at the cathode only in a voltaic cell.
C)The free energy change, Δ G, is negative for an electrolytic cell.
D)The cathode is labeled as positive (+)in a voltaic cell but negative (-)in an electrolytic cell.
E)Reduction occurs at the anode in an electrolytic cell.

Question 40

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

A)Cu( s)→ Cu ²⁺( aq)+ 2e ⁻
B)Cu ²⁺( aq)+ 2e ⁻ → Cu( s)
C)Ag( s)→ Ag ⁺( aq)+ e ⁻
D)Ag ⁺( aq)+ e ⁻ → Ag( s)
E)Cu( s)+ 2Ag ⁺( aq)→ Cu ²⁺( aq)+ 2Ag( s)

Question 41

When metal A is placed in a solution of metal ions B²⁺, a reaction occurs between A and B²⁺, and metal ions A²⁺ appear in the solution. When metal B is placed in acid solution, gas bubbles form on its surface. When metal A is placed in a solution of metal ions C²⁺, no reaction occurs. Which of the following reactions would not occur spontaneously?

A)C( s)+ 2H ⁺( aq)→ H ₂( g)+ C ²⁺( aq)
B)C( s)+ A ²⁺( aq)→ A( s)+ C ²⁺( aq)
C)B( s)+ C ²⁺( aq)→ C( s)+ B ²⁺( aq)
D)A( s)+ 2H ⁺( aq)→ H ₂( g)+ A ²⁺( aq)
E)B( s)+ 2H ⁺( aq)→ H ₂( g)+ B ²⁺( aq)

Question 42

Which of the following conditions is most likely to apply to a fully-charged secondary cell?

A)E _cell = E° _cell
B)E° _cell = 0
C)Q = 1
D)Q < K
E)Q = K

Question 43

Examine the following half-reactions and select the strongest oxidizing agent among the species listed. Cr²⁺(aq) + 2e⁻ ⇄ Cr(s) E° = -0.913 V
Fe²⁺(aq) + 2e⁻⇄ Fe(s) E° = -0.447 V
Sr²⁺(aq) + 2e⁻⇄ Sr(s) E° = -2.89 V
Co²⁺(aq) + 2e⁻⇄ Co(s) E° = -0.28 V

A)Cr ²⁺( aq)
B)Fe( s)
C)Fe ²⁺( aq)
D)Sr ²⁺( aq)
E)Co ²⁺( aq)

Question 44

Calculate E°_cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. I₂(s) + 2e⁻ ⇄ 2I⁻ (aq) E° = 0.53 V
Cr³⁺(aq) + 3e⁻ ⇄ Cr(s) E° = −0.74 V
Overall reaction:
2Cr(s) + 3I₂(s) → 2Cr³⁺(aq) + (aq) + 6I⁻(aq)

A)E° _cell = −1.27 V, spontaneous
B)E° _cell = −1.27 V, nonspontaneous
C)E° _cell = 1.27 V, spontaneous
D)E° _cell = 1.27 V, nonspontaneous
E)E° _cell = 1.54 V, spontaneous

Question 45

The voltaic cell made up of cobalt, copper, and their M²⁺ ions, 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)None of these choices are correct.

Question 46

Given that E° for X + e^- → Y is greater than E° for A + 2e^- → B, it is correct to say that, under standard 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 47

Calculate the potential of a voltaic cell (E°_cell) if it is required to do 5.43 × 10⁻³ kJ of work when a charge of 2.50 C is transferred.

A)2.17 × 10 ³ V
B)2.17 × 10 ⁻³ V
C)2.17 V
D)13.6 V
E)1.36 × 10 ⁻² V

Question 48

Calculate E°_cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. O₂(g) + 4H⁺(aq) + 4e⁻ ⇄ 2H₂O(l) E° = 1.229 V
Al³⁺(aq) + 3e⁻ ⇄ Al(s) E° = −1.662 V
Overall reaction:
4Al(s) + 3O₂(g) + 12H⁺(aq) → 4Al³⁺(aq) + 6H₂O(l)

A)E° _cell = −2.891 V, nonspontaneous
B)E° _cell = −2.891 V, spontaneous
C)E° _cell = 2.891 V, nonspontaneous
D)E° _cell = 2.891 V, spontaneous
E)None of these choices are correct.

Question 49

What is the E°_cell for the cell represented by the combination of the following half-reactions? ClO₄(aq) + 8H(aq) + 8e ⇄ Cl^-(aq) + 4H₂O(l) E° = 1.389 V
VO₂(aq) + 2H(aq) + e^- ⇄ VO(aq) + H₂O(l) E° = 0.991 V

A)-0.398 V
B)-2.380 V
C)0.398 V
D)2.380 V
E)None of these choices are correct.

Question 50

A battery is considered "dead" when

A)Q < 1.
B)Q = 1.
C)Q> 1.
D)Q = K.
E)Q/K = 0.

Question 51

What is the E°_cell for the cell represented by the combination of the following half-reactions? 2Hg²⁺(aq) + 2e^- ⇄ Hg₂²⁺(aq) E° = 0.92 V
Cr³⁺(aq) + 3e^- ⇄ Cr(s) E° = -0.74 V

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

Question 52

Examine the following half-reactions and select the weakest oxidizing agent among the species listed. AuBr₄(aq) + 3e⁻ ⇄ Au(s) + 4Br⁻(aq) E° = 0.854 V
Mn²⁺(aq) + 2e⁻⇄ Mn(s) E° = −1.185 V
K⁺(aq) + e⁻⇄ K(s) E° = −2.931 V
F₂O(aq) + 2H⁺(aq) + 4e⁻⇄ 2F⁻(aq) + H₂O(l) E° = 2.153 V

A)AuBr ₄⁻( aq)
B)Mn ²⁺( aq)
C)K ⁺( aq)
D)F ₂O( aq)
E)H ⁺( aq)

Question 53

Calculate E°_cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. Co³⁺(aq) + e⁻ ⇄ Co²⁺(aq) E° = 1.82 V
MnO₄⁻(aq) + 2H₂O(l) + 3e^- ⇄ MnO₂(s) + 4OH⁻(aq) E° = 0.59 V
Overall reaction:
MnO₄⁻(aq) + 2H₂O(l) + 3Co²⁺(aq) → MnO₂(s) + 3Co³⁺(aq) + 4OH⁻(aq)

A)E° _cell = -1.23 V, spontaneous
B)E° _cell = -1.23 V, nonspontaneous
C)E° _cell = 1.23 V, spontaneous
D)E° _cell = 1.23 V, nonspontaneous
E)E° _cell = -0.05 V, nonspontaneous

Question 54

Examine the following half-reactions and select the strongest reducing agent among the species listed. PbI₂(s) + 2e⁻ ⇄ Pb(s) + 2I⁻(aq) E° = −0.365 V
Ca²⁺(aq) + 2e⁻ ⇄ Ca(s) E° = −2.868 V
Pt²⁺(aq) + 2e⁻ ⇄ Pt(s) E° = 1.18 V
Br₂(l) + 2e⁻ ⇄ 2Br⁻(aq) E° = 1.066 V

A)Pb( s)
B)Ca( s)
C)Pt( s)
D)Br ⁻( aq)
E)Pt ²⁺( aq)

Question 55

Examine the following half-reactions and select the strongest oxidizing agent among the substances. [PtCl₄]²⁻(aq) + 2e⁻ ⇄ Pt(s) + 4Cl⁻(aq) E° = 0.755 V
RuO₄(s) + 8H⁺(aq) + 8e⁻ ⇄ Ru(s) + 4H₂O(l) E° = 1.038 V
FeO₄²⁻(aq) + 8H⁺(aq) + 3e⁻ ⇄ Fe³⁺(aq) + 4H₂O(l) E° = 2.07 V
H₄XeO₆(aq) + 2H⁺(aq) + 2e⁻ ⇄ XeO₃(aq) + 3H₂O(l) E° = 2.42 V

A)[PtCl ₄] ^2-( aq)
B)RuO ₄( s)
C)HFeO ₄⁻ ( aq)
D)H ₄X _eO ₆( aq)
E)Cl ⁻( aq)

Question 56

Calculate E°_cell and indicate whether the overall reaction shown is spontaneous or nonspontaneous. H₂O₂(aq) + 2H⁺(aq) + 2e⁻ ⇄ 2H₂O(l) E° = 1.77 V
Fe³⁺ (aq) + e⁻ ⇄ Fe²⁺(aq) E° = 0.77 V
Overall reaction:
2Fe³⁺(aq) + 2H₂O(l) → H₂O₂(aq) + 2H⁺(aq) + 2Fe²⁺(aq)

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 57

The redox reaction of peroxydisulfate with iodide has been used for many years as part of the iodine clock reaction which introduces students to kinetics. 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? S₂O₈²⁻(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 are correct.

Question 58

Examine the following half-reactions and select the strongest reducing agent among the species listed. HgO(s) + H₂O(l) + 2e⁻ ⇄ Hg(l) + 2OH⁻(aq) E° = 0.0977 V
Zn(OH)₂(s) + 2e⁻ ⇄ Zn(s) + 2OH⁻(aq) E° = −1.25 V
Ag₂O(s) + H₂O(l) + 2e⁻ ⇄ Ag(s) + 2OH⁻(aq) E° = 0.342 V
B(OH)₃(aq) + 7H⁺(aq) + 8e⁻ ⇄ BH₄⁻(aq) + 3H₂O(l) E° = −0.481 V

A)Hg( l)
B)Zn( s)
C)Ag( s)
D)BH ₄ ⁻( aq)
E)Zn(OH)₂( s)

Question 59

Examine the following half-reactions and select the weakest reducing agent among the substances. Cr(OH)₃(s) + 3e⁻ ⇄ Cr(s) + 3OH⁻(aq) E° = −1.48 V
SnO₂(s) + 2H₂O(l) + 4e⁻ ⇄ Sn(s) + 4OH⁻(aq) E° = −0.945 V
MnO₂(s) + 4H⁺(aq) + 2e⁻ ⇄ Mn²⁺(aq) + 2H₂O(l) E° = 1.224 V
Hg₂SO₄(s) + 2e⁻ ⇄ 2Hg(l) + SO₄²⁻(aq) E° = 0.613 V

A)Cr( s)
B)Sn( s)
C)Mn ²⁺( aq)
D)Hg( l)
E)OH ⁻( aq)

Question 60

A voltaic cell has a standard cell potential equal to 0.74 V. If the standard electrode (reduction) potential for the anode is −0.22 V, what is the standard electrode potential for the cathode?

A)0.96 V
B)0.52 V
C)-0.52 V
D)-0.96 V
E)Need to know the cell reaction in order to calculate the answer.

Question 61

The following half-reactions occur in the mercury battery used in calculators. If E°_cell = 1.357 V, calculate the equilibrium constant for the cell reaction at 25°C. (Assume the stoichiometric coefficients in the cell reaction are all equal to 1.) HgO(s) + H₂O(l) + 2e⁻ ⇄ Hg(l) + 2OH⁻(aq)
ZnO(s) + H₂O(l) + 2e⁻ ⇄ Zn(s) + 2OH⁻(aq)

A)9.4 × 10 ²²
B)7.5 × 10 ⁴⁵
C)6.4 × 10 ⁶³
D)7.8 × 10 ⁹¹
E)> 9.9 × 10 ⁹⁹

Question 62

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 8.30 × 10⁻⁷. Calculate ΔG° for the reaction at 25°C.

A)−15.1 kJ
B)−34.7 kJ
C)15.1 kJ
D)34.7 kJ
E)None of these choices are correct.

Question 63

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 × 10 ¹
B)1 × 10 ¹
C)1
D)1 × 10 ⁻¹
E)5 × 10 ⁻²

Question 64

What is the value of the equilibrium constant for the cell reaction below at 25°C? E°_cell = 0.61 V 2Cr(s) + 3Pb²⁺(aq) ⇄ 3Pb(s) + 2Cr³⁺(aq)

A)4.1 × 10 ²⁰
B)8.2 × 10 ³⁰
C)3.3 × 10 ⁵¹
D)7.4 × 10 ⁶¹
E)> 9.9 × 10 ⁹⁹

Question 65

Consider the nonaqueous cell reaction 2Na(l) + FeCl₂(s) ⇄ 2NaCl(s) + Fe(s)
For which E°_cell = 2.35 V at 200°C. ΔG° at this temperature is

A)453 kJ.
B)−453 kJ.
C)907 kJ.
D)−907 kJ.
E)None of these choices are correct.

Question 66

Calculate ΔG° for the oxidation of 3 moles of copper by nitric acid. Cu²⁺(aq) + 2e⁻ ⇄ Cu(s) E° = 0.34 V
NO₃⁻(aq) + 4H⁺(aq) + 3e⁻ ⇄ NO(g) + 2H₂O(l) E° = 0.957 V

A)−120 kJ
B)−180 kJ
C)−240 kJ
D)−300 kJ
E)−360 kJ

Question 67

The value of the equilibrium constant for the reaction of nickel(II) ions with cadmium metal is 1.17 × 10⁵. Calculate ΔG° for the reaction at 25°C.

A)−12.6 kJ
B)−28.9 kJ
C)12.6 kJ
D)28.9 kJ
E)None of these choices are correct.

Question 68

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)0.0001 M
B)0.0007 M
C)0.005 M
D)0.03 M
E)0.05 M

Question 69

A concentration cell consists of two Al/Al³⁺electrodes. The electrolyte in compartment A is 0.050 M Al(NO₃)₃ and in compartment B is 1.25 M Al(NO₃)₃. What is the voltage of the cell at 25°C?

A)0.083 V
B)0.062 V
C)0.041 V
D)0.028 V
E)None of these choices are correct.

Question 70

Calculate ΔG° for the reaction of iron(II) ions with one mole of permanganate ions. MnO₄⁻(aq) + 8H⁺(aq) + 5e⁻ ⇄ Mn²⁺(aq) + 4H₂O(l) E° = 1.51 V
Fe³⁺(aq) + e⁻ ⇄ Fe²⁺(aq) E°= 0.77 V

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

Question 71

A concentration cell consists of two Zn/Zn²⁺ electrodes. The electrolyte in compartment A is 0.10 M Zn(NO₃)₂ and in compartment B is 0.60 M Zn(NO₃)₂. What is the voltage of the cell at 25°C?

A)0.010 V
B)0.020 V
C)0.023 V
D)0.046 V
E)None of these choices are correct.

Question 72

What is the value of the equilibrium constant for the cell reaction below at 25°C? E°_cell = 0.30 V Sn²⁺(aq) + Fe(s) ⇄ Sn(s) + Fe²⁺(aq)

A)1.2 × 10 ⁵
B)1.4 × 10 ¹⁰
C)8.6 × 10 ⁻⁶
D)7.1 × 10 ⁻¹¹
E)2.3 × 10 ²³

Question 73

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 8.30 × 10⁻⁷. Calculate E°_cell for the reaction at 25°C.

A)−0.36 V
B)−0.18 V
C)−0.12 V
D)−0.060 V
E)None of these choices are correct.

Question 74

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 are correct.

Question 75

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 choices are correct.

Question 76

Calculate E°_cell for the reaction of nickel(II) ions with cadmium metal at 25°C. K = 1.17 × 10⁵Ni²⁺(aq) + Cd(s) → Cd²⁺(aq) + Ni(s)

A)0.075 V
B)0.10 V
C)0.12 V
D)0.15 V
E)0.30 V

Question 77

The value of E°_cell for the reaction 2Cr³⁺(aq) + 6Hg(l) → 2Cr(s) + 3Hg₂²⁺(aq)
Is 1.59 V. Calculate ΔG° for the reaction.

A)−921 kJ
B)−767 kJ
C)−460 kJ
D)−307 kJ
E)None of these choices are correct.

Question 78

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 = 1.13 V at 25°C.

A)0.001 M
B)0.002 M
C)0.01 M
D)0.02 M
E)0.04 M

Question 79

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 × 10 ⁵ kJ.
B)−3.94 × 10 ² kJ.
C)−1.97 × 10 ⁵ kJ.
D)−7.87 × 10 ² kJ.
E)None of these choices are correct.

Question 80

A voltaic cell consists of a Ag/Ag⁺ electrode (E° = 0.80 V) and a Fe²⁺/Fe³⁺ electrode (E° = 0.77 V) with the following initial molar concentrations: [Fe²⁺] = 0.30 M; [Fe³⁺] = 0.10 M; [Ag⁺] = 0.30 M. What is the equilibrium concentration of Fe³⁺? (Assume the anode and cathode solutions are of equal volume, and a temperature of 25°C.)

A)0.030 M
B)0.043 M
C)0.085 M
D)0.11 M
E)0.17 M