CHEM 1412. Chapter 20. Electrochemistry (Homework) Ky

pg. 1 CHEM 1412. Chapter 20. Electrochemistry (Homework) Ky

CHEM 1412. Chapter 20. Electrochemistry (Homework) Ky

1.

Complete and balance the following redox equation using the smallest whole-number coefficients. What is the coefficient of Sn in the balanced equation?

Sn + HNO3 → SnO2 + NO2 + H2O (acidic solution)

A. 1

B. 2

C. 3

D. 4

E. 5

2.

Complete and balance the following redox equation. What is the coefficient of H2O when the equation is balanced using the set of smallest whole-number coefficients?

MnO4– + SO32– → Mn2+ + SO42– (acidic solution)

A. 3

B. 4

C. 5

D. 8

E. None of these.


3.

Complete and balance the following redox equation. What is the coefficient of OH– when the equation is balanced using the set of smallest whole-number coefficients?

MnO4– + I– → MnO2 + IO3– (basic solution)

A. 1

B. 2

C. 4

D. 10

E. None of these.


4. Given the following notation for an electrochemical cell

Pt(s) | H2(g) | H+(aq) || Ag+(aq) | Ag(s) what is the balanced overall (net) cell reaction?

A.

2H+(aq) + 2Ag+(aq) → H2(g) + 2Ag(s)

B.

H2(g) + 2Ag(s) → H+(aq) + 2Ag+(aq)

C.

2H+(aq) + 2Ag(s) → H2(g) + 2Ag+(aq)

D.

H2(g) + Ag+(aq) → H+(aq) + Ag(s)

E.

H2(g) + 2Ag+(aq) → 2H+(aq) + 2Ag(s)


5.

Determine the cell diagram for the reaction below. Assume platinum electrodes are used when no other solid is present. Cl2(g) + Sn2+(aq) → Sn4+(aq) + 2Cl-(aq)

A. Pt(s) | Cl2(g) | Cl-(aq) || Sn2+(aq), Sn4+(aq) | Pt(s) B. Pt(s) | Sn2+(aq), Sn4+(aq) || Cl2(g) | Cl-(aq) | Pt(s) C. Pt(s) | Sn4+(aq), Sn2+(aq) || Cl-(aq) | Cl2(g) | Pt(s) D. Pt(s) | Cl-(g) | Cl2(aq) || Sn4+(aq), Sn2+(aq) | Pt(s) E. Pt(s) | Cl2(g) | Sn2+(aq) || Sn4+(aq), Cl-(aq) | Pt(s)

6. Which of the following is true concerning a galvanic cell?

A. Oxidation occurs at the anode and is where anions move towards

B. Oxidation occurs at the cathode and is where anions move towards

C. Oxidation occurs at the anode and is where cations move towards

D. Oxidation occurs at the cathode and is where cations move towards

E. Reduction occurs at the anode and is where anions move towards

7. Which of the following is true concerning a galvanic cell?

A. Reduction occurs at the anode and is where anions move towards

B. Reduction occurs at the cathode and is where anions move towards

C. Reduction occurs at the cathode and is where cations move towards

D. Oxidation occurs at the anode and is where cations move towards

E. Oxidation occurs at the cathode and is where cations move towards


8. Consider an electrochemical cell constructed from the following half cells, linked by a KCl salt bridge.

- a Fe electrode in 1.0 M FeCl2 solution

- a Ni electrode in 1.0 M Ni(NO3)2 solution

When the cell is running spontaneously, which choice includes only true statements and no false ones?

A. The nickel electrode loses mass and the nickel electrode is the cathode. B. The nickel electrode gains mass and the nickel electrode is the cathode. C. The iron electrode gains mass and the iron electrode is the anode. D. The iron electrode loses mass and the iron electrode is the cathode.


9.

A galvanic cell has the overall reaction: Zn(s) + 2Eu(NO3)3(aq) → Zn(NO3)2(aq) + 2Eu(NO3)2(aq) Which is the half reaction occurring at the anode?

A.

NO3-(aq) + 4H+(aq) + 3e- → NO(g) + 2H2O(l)

B.

NO2(g) + H2O(l) → NO3-(aq) + 2H+(aq) + e-

C.

Zn(s) → Zn2+(aq) + 2e-

D.

Eu3+(aq) + e- → Eu2+

E.

Zn(s) + 2e- →Zn2+(aq)-


10.

Calculate E°cell for a silver-aluminum cell in which the cell reaction is

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. none of these

11.

For the reaction, 2Cr2+ + Cl2(g) → 2Cr3+ + 2Cl–, E°cell is 1.78 V. Calculate E°cell for the related reaction Cr3+ + Cl– → Cr2+ + 1/2Cl2(g).

A. 1.78 V

B. 0.89 V

C. –1.78 V

D. –0.89 V

E. None of these.


12.

The overall reaction 2Co3+(aq) + 2Cl–(aq) → 2Co2+(aq) + Cl2(g) has the standard cell voltage E°cell= 0.46 V. Given E° = 1.36 V for the reaction Cl2(g) + 2e– → 2Cl–(aq), calculate the standard reduction potential for the following the half reaction at 25°C: Co3+ + e– → Co2+

A. 1.82 V

B. –0.90 V

C. 0.90 V

D. –1.82 V

E. –1.36 V


13. Which one of the following reactions will occur spontaneously at standard-state conditions and 25°C?

A.

Br2(l) + Sn(s) → 2Br-(aq) + Sn2+(aq)

B.

Fe2+(aq) + Ni(s) → Fe(s) + Ni2+(aq)

C.

2Ag+(aq) 2H2O(l) → 2Ag(s) + 2H+(aq) + H2O2(aq)

D.

Mn2+(aq) + Cd(s) → Mn(s) + Cd2+(aq)

E.

Cr3+(aq) + 3Cu+(aq) → Cr(s) + 3Cu2+(aq)


14.

Consider the following standard reduction potentials in acid solution:

The strongest reducing agent among those shown above is

A. Fe3+. B. Fe2+. C. Br–. D. Al3+. E. Al.

15.


Which is the weakest oxidizing agent in this list?

A. Al3+(aq)

B. Al(s)

C. I–(aq) D. I2(s) E. Sn4+(aq)


16.


The strongest reducing agent listed above is

A. Cr3+. B. Cr. C. Mn2+. D. Co. E. MnO4–.

17. Using a table of standard electrode potentials, decide which of the following statements is completely true. A. Cu2+ can oxidize H2, and Fe can reduce Mn2+. B. Ni2+ can oxidize Cu2+, and Fe2+ can reduce H+. C. Fe2+ can oxidize H2, and Fe2+ can reduce Au3+. D. Br2 can oxidize Ni, and H2 can reduce Mn2+. E. H+ can oxidize Fe, and Ni can reduce Br2.


18. Which one of the following reagents is capable of oxidizing Br– (aq) to Br2(l) under standard-state conditions?

A. I– (aq) B. NO3– (aq) C. Ag+ (aq) D. Al3+ (aq) E. Au3+ (aq)

19. Which one of the following reagents is capable of reducing Fe3+ (1 M) to Fe2+ (1 M)?

A. H2(1 atm) B. NO3– (1 M) C. O2(1 atm) D. Br– (1 M) E. H+ (1 M)

20.

The half-cell reaction for the oxidation of H2O(l) to O2(g) is given below. 2H2O(l) → O2(g) + 4H+(aq) + 4e–

Which choice lists all of the following species that can oxidize H2O to O2(g) under standard-state conditions?

MnO4–(aq), Cl2(g), Pb2+(aq), Cl– (aq), Ag+(aq)

A. Cl–(aq) only

B. Cl2(g) only

C. Pb2+(aq) and Ag+(aq)

D. Cl–(aq) and MnO4–(aq)

E. MnO4–(aq) and Cl2(g)


21.

Consider the following reaction: 2Fe2+(aq) + Cu2+ → 2Fe3+(aq) + Cu. When the reaction comes to equilibrium, what is the cell voltage?

A. 0.43 V

B. 1.11 V

C. 0.78 V

D. –0.43 V

E. 0 V

22.

Given the following standard reduction potentials,

calculate the formation constant of Ag(NH3)2+ at 25°C.

A. 6.1 × 10–15

B. 1.5 × 10–13

C. 6.9 × 1012

D. 1.6 × 1014

E. None of these


23. For the electrochemical cell Pt(s) | H2(1 atm) | H+(1 M) || Cu2+(1 M) | Cu(s), which one of the following changes will cause an increase in the cell voltage?

A. Lower the H2(g) pressure. B. Increase the size/mass of the copper electrode. C. Lower the H+(aq) concentration. D. Decrease the concentration of Cu2+ ion. E. None of the above.

24.

Calculate the cell emf for the following reaction at 25°C: 2Ag+(0.010 M) + H2(1 atm) → 2Ag(s) + 2H+(pH = 10.0)

A. 1.04 V

B. 1.27 V

C. 0.92 V

D. 0.56 V

E. 0.80 V


25.

Consider an electrochemical cell based on the spontaneous reaction

2AgCl(s) + Zn(s) → 2Ag(s) + 2Cl– + Zn2+. If the zinc ion concentration is kept constant at 1 M, and the chlorine ion concentration is decreased from 1 M to 0.001 M, the cell voltage should

A. increase by 0.06 V. B. increase by 0.18 V. C. decrease by 0.06 V. D. decrease by 0.18 V. E. increase by 0.35 V.

26.

Consider an electrochemical cell involving the overall reaction

2AgBr(s) + Pb(s) → Pb2+ + 2Ag(s) + 2Br–. Each half-reaction is carried out in a separate compartment. The anion included in the lead half-cell is NO3–. The cation in the silver half-cell is K+. The two half-cells are connected by a KNO3 salt bridge. If [Pb2+] = 1.0 M, what concentration of Br– ion will produce a cell emf of 0.25 V at 298 K?

Given: AgBr(s) + e– → Ag + Br–, E° = +0.07 V.

A. 0.02 M

B. 0.14 M

C. 0.38 M

D. 1.0 M

E. 7.0 M


27. How many coulombs of charge are required to cause reduction of 0.20 mole of Cr3+ to Cr?

A. 0.60 C

B. 3.0 C

C. 2.9 × 104 C

D. 5.8 × 104 C

E. 9.65 × 104 C

28. A metal object is to be gold-plated by an electrolytic procedure using aqueous AuCl3 electrolyte. Calculate the number of moles of gold 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. 160 mol

29. A current of 2.50 A was passed through an electrolytic cell containing molten CaCl2 for 4.50 hours. How many moles of calcium metal should be deposited?

A. 5.83 × 10–5 mol B. 0.210 mol C. 0.420 mol D. 0.840 mol E. 1.95 × 109 mol


30. How many coulombs (C) of electrical charge must pass through an electrolytic cell to reduce 0.44 mol Ca2+ ion to calcium metal?

A. 190,000 C

B. 85,000 C

C. 21,000 C

D. 42,500 C

E. 0.88 C

31. How many coulombs would be required to electroplate 35.0 grams of chromium by passing an electrical current through a solution containing CrCl3?

A. 6.50 × 104 C

B. 2.16 × 104 C

C. 6.40 × 104 C

D. 1.95 × 105 C

E. 1.01 × 107 C

32. How long will it take to produce 78 g of Al metal by the reduction of Al3+ in an electrolytic cell with a current of 2.0 A?

A. 0.01 s

B. 420 s

C. 13 h

D. 116 h

E. 1.0 × 1012 s


33.

Suppose the reaction Pb(s) + 2H+(aq) → Pb2+(aq) + H2(g) is carried out at pH = 4.00 and at a hydrogen gas pressure of 1.00 atm. The concentration of lead(II) ions that causes this reaction to be at equilibrium is

A. 2.5 M. B. 1.6 × 10–2 M. C. 2.5 × 10–4 M. D. 1.6 × 10–6 M. E. 0.40 M.

34. Which of these metals will be oxidized in hydrochloric acid under standard conditions at 25°C?

A. Ag

B. Au

C. Hg

D. Cu

E. Zn

35. Which of these metals will not be oxidized in hydrochloric acid under standard conditions at 25°C?

A. Al B. Fe

C. Ag

D. Ni E. Mg


36.

Consider the reaction 2Fe3+(aq) + Fe(s) 3Fe2+(aq). Find the equilibrium constant for this reaction at 25°C.

A. 1 × 1011

B. 8 × 1040

C. 3 × 1020

D. 7 × 10–12

E. 1 × 10–41

37.

Consider the reaction Hg2+(aq) + Hg(l) Hg22+(aq). Find the equilibrium constant for this reaction at 25°C.

A. 2 × 101

B. 6 × 1059

C. 4 × 10–3

D. 7 × 10–2

E. 2 × 102


38. Which of the following would be considered a Lead Storage Battery?

A.

C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(l)

B.

Pb(s) + PbO2(s) + 4H+(aq) + 2SO42-(aq) → 2PbSO4(s) + 2H2O(l)

C.

Zn(s) + 2NH4+(aq) + 2MnO2(s) → Zn2+(aq) + 2NH3(aq) + H2O(l) + Mn2O3(s)

D.

Zn(Hg) + HgO(s) → ZnO(s) + Hg(l)

E.

2Fe(s) + O2(g) + 4H+(aq) → 2Fe2+(aq) + 2H2O(l)


39.

Write the formula of the strongest oxidizing agent given the following standard reduction potentials in acid solution:

A. Sn4+

B. O2

C. Zn2+

D. 2H2O

E. None of the above

40.

Calculate ∆G° (kJ/mol) for the following electrochemical cell: Be(s) | Be2+(aq) || Mn2+(aq)| Mn(s)

A. -540 kJ/mol B. -560 kJ/mol C. -580 kJ/mol D. -600 kJ/mol E. None of the above


41.

Determine the equilibrium constant for the following reaction at 25°C.

2I– (aq) + Br2(l) I2(s) + 2Br–(aq).

A. 1.8 × 1018

B. 2.8 × 1018

C. 3.8 × 1018

D. 4.8 × 1018


42. Aluminum metal is formed by the electrolysis of Al2O3 in molten cryolite. How many minutes are required to form 10.0 g of Al using a current of 30 A?

A. 55.6 min

B. 57.6 min

C. 59.6 min

D. 61.6 min


43. How many moles of H2 are produced by 5.00 A of current passing through a cell containing aqueous NaCl for 4.00 × 102 s?

A. 0.0104 mol B. 0.0124 mol C. 0.0144 mol D. 0.0164 mol E. None of the above


44. A standard hydrogen electrode is immersed in an acetic acid solution. This electrode is connected by an external circuit to an iron nail dipping into 0.10 M FeCl2. If Ecell is found to be 0.24 V, what is the pH of the acetic acid solution?

A. 3.88

B. 3.68

C. 3.48

D. 3.28


45. An electroplating solution is made up of nickel(II) sulfate. How much time would it take to deposit 0.500 g of metallic nickel on a custom car part using a current of 3.00 A?

A. 8.53 min

B. 8.73 min

C. 8.93 min

D. 9.13 min



CHEM 1412. Chapter 18. Electrochemistry (Homework) Ky Key

1. A 2. A 3. B 4. E 5. B 6. A 7. C 8. B 9. C 10. D


11. C 12. A 13. A 14. E 15. A 16. B 17. E 18. E 19. A 20. E 21. E 22. C 23. C


24. B 25. B 26. B 27. D 28. A 29. B 30. B 31. D 32. D 33. C 34. E 35. C 36. B


37. E 38. B 39. B 40. C 41. A 42. C 43. A 44. A 45. D

CHEM 1412. Chapter 20. Electrochemistry (Homework) Ky

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