1.which half–cell reaction correctly represents ... · 26.base your answer on the table below....

A) Sn4+ ® Sn2+ + 2e–

B) Sn2+ ® Sn4+ + 2e–

C) Sn4+ + 2e– ® Sn2+

D) Sn2+ + 2e– ® Sn4+

E) Sn4+ + Sn2+ ® Sn6+ + 2e–

1. Which half–cell reaction correctly represents reduction?

2.

A) Co B) Co2+

C) Sn D) Sn2+

E) both Sn and Co

In the electrochemical cell, Co/Co2+||Sn2+/Sn,which substance is the electrode that gains weight?

3. For the following question refer to the table below.

A) +1.65 B) +0.85 C) –0.05 D) –0.85 E) –1.65

What is the E° for the reaction: Hg ® Hg2+ + 2e–?

A) Sn2+ ® Sn4+ + 2e– B) Ag+ + e– ® AgC) Sn2+ + 2e– ® Sn4+ D) Ag+ ® Ag + e–

E) Sn2+ + Sn4+ ® 2e–

4. In the reaction

Sn2+(aq) + 2 Ag+(aq) ® Sn4+(aq) + 2 Ag(s)

What is the half–reaction equation for the oxidizingagent above?

A) increase the cell voltageB) maintain electrical neutralityC) increase the oxidation–reduction rateD) supply a travel pathway for electronsE) increase the rate of attainment of equilibrium

5. The function of the salt bridge in an electrochemical cellis to

A) It gains protonsB) It loses protonsC) It gains electronsD) It loses electronsE) It loses an electron and gains a proton

6. In the half–cell reaction Ca ®Ca2+ + 2e–, which is trueof the calcium atom?

A) Br2 ® 2 Br– + 2e–

B) Br2 + 2e– ® 2 Br–

C) H2 ® 2 H+ + 2e–

D) H2 + 2e– ® 2 H+

E) H2 + 2 H+ ® 2e– + 4 H

7. Which half–reaction correctly represents oxidation?

8.

A) AgB) Ag+

C) FeD) Fe2+

E) It cannot be determined from the information given

What electrode gains weight in the electrochemical cell? Fe/Fe2+|| Ag+/Ag

A) Au ® Au3+ + 3e–

B) Au + 3e– ® Au3+

C) Au3+ ® Au + 3e–

D) Au3+ + 3e– ® AuE) Au + Au3+ ® 3e– + Au3+

9. Which half-reaction would occur at the cathode of anelectrochemical cell?

10. Which substance is the electrode that gains weightduring the operation of this electrochemical cell?Cr/Cr3+ || Pb2+/Pb

A) Cr B) Cr3+

C) Pb D) Pb2+

E) both Cr and Pb

11. Which is the most easily reduced?

A) Cl2 B) Br2 C) Hg2+ D) I2 E) I–

12. Which is the most easily oxidized?

A) Cl– B) Br– C) Hg(l) D) I– E) Br2

13. Which is the strongest oxidizing agent?

A) HNO3 B) Ag+

C) Cu D) H2

E) H+

14. Which is the strongest reducing agent?

A) Cl2 B) Br2 C) Cr D) Cr3+ E) Al

15. What is the oxidation potential for the reaction?

Cu ®Cu2+ + 2e–

A) -0.52 V B) -0.34 VC) +0.18 V D) +0.34 VE) +0.52 V

16. What is the standard reduction potential of Na if thestandard hydrogen half-cell potential is changed from0.00 to +0.40 volts?

A) -3.11 V B) -2.71 VC) -2.31 V D) 0.00 VE) +3.11 V

17. What is the electrode potential of the standard hydrogenhalf-cell reaction?

A) -0.83 V B) 0.00 VC) +0.83 V D) +0.96 VE) +1.23 V

18. What is the standard electrode potential, E°, for thishalf-reaction?

2Ag+ + 2e– ® 2Ag

A) –0.80 V B) –1.60 VC) +0.40 V D) +0.80 VE) +1.60 V


A) +1.48 V B) +0.74 VC) 0.00 V D) –0.74 VE) –1.48 V

What is the E° for this reaction?

2 Cr ® 2 Cr3+ + 6e–

A) Ag B) Ag+

C) Mg D) Mg2+

E) both Ag and Mg

20. The negative ions go to which electrode in the voltaiccell

Mg/Mg2+||Ag+/Ag?

A) PbB) Pb2+

C) ZnD) Zn2+

E) It cannot be determined unless the potentials areknown.

21. To which electrode do the electrons move in the cell

Zn/Zn2+||Pb2+/Pb?

A) anode to the cathode through the wireB) cathode to the anode through the wireC) anode to the cathode through the salt bridgeD) cathode to the anode through the salt bridgeE) cathode to the anode through the wire and anode to

the cathode through the salt bridge

22. In an electrochemical cell, the positive ions go from the

A) anode to the cathode through the wireB) cathode to the anode through the wireC) anode to the cathode through the salt bridgeD) cathode to the anode through the salt bridgeE) anode to the cathode through the wire and cathode

to the anode through the salt bridge

23. In an electrochemical cell, the electrons go from the

24. Which is the cathode of this electrochemical cell?

Cr + Au3+ ® Cr3+ + Au

A) CrB) Au3+

C) Cr3+

D) AuE) It cannot be determined unless the potentials are

known25. Base your answer on the table below.

A) Al3+ B) BaC) Ba2+ D) MnE) None of the above

Which is an oxidizing agent capable of converting Mgto Mg2+, but not Zn to Zn2+?

26. Base your answer on the table below.

A) Fe3+ reduces Fe2+ to Fe.B) Fe oxidizes Fe2+ to Fe3+.C) Fe reduces Fe3+ to Fe2+.D) Fe3+ oxidizes Fe to Fe2+.E) Fe2+ reduces Fe3+ to Fe.

Which statement is true?


A) Sn2+ B) Sn4+ C) Nb D) Nb3+ E) 2e–

Which substance is most easily oxidized?


A) Br2 B) Cl– C) Cu D) I2 E) Mn2+

Which is an agent which oxidizes H2 to H+, but notHg to Hg2+?


A) clear B) greenC) purple D) yellowE) brown

Ions of the transition elements are generally colored.What color will the final solution be when a solution ofFe(NO3)2 is mixed with an acid solution of KMnO4?


A) Br2 will oxidize the chloride ion, but not the iodideion.

B) Br2 will oxidize the iodide ion, but not thechloride ion.

C) I2 will oxidize the chloride ion, but not thebromide ion.

D) I2 will oxidize the chloride ion, but not thebromide ion.

E) Cl2 will oxidize the bromide ion, but not the iodideion.



A) 2.00 V B) 1.00 VC) 0.74 V D) 0.48 VE) –1.00 V

What is the net voltage of this electrochemical cell? Cr/Cr3+ || Ni2+/Ni


A) +0.89 V B) +0.76 VC) +0.63 V D) –0.63 VE) –0.89 V

What is the net potential developed by anelectrochemical cell with these half reactions?

33.

A) Al and Ca B) Al and CuC) Ca and Cu D) Cr and CuE) Ca only

Which will react with hydrochloric acid?


A) I–(aq), but not fluorine, F2(g).B) F2(g), but not chlorine, Cl2(g).C) I2(s), but not fluoride ion, F–(aq).D) Cl2(g), but not fluoride ion, F–(aq).E) none of these other ions or gases.

Which statement is true? Bromide ion, Br–(aq), reduces


A) WaterB) Nitrous acidC) Hydrochloric acidD) Acid and permanganate ionE) Nitric acid

When magnesium metal is added to an unknown acidsolution, a brownish colored gas is observed. What ismost likely to be the unknown acid?


A) Ag B) AuC) Cl– D) H+ + MnO4–

E) Sn2+

Which species will reduce Cu2+ to Cu?


A) –0.29 V B) 0.29 VC) 1.41 V D) 1.43 VE) 3.67 V

What is the initial net cell potential for theelectrochemical cell, Ga/Ga3+||Hg2+/Hg?


A) +1.58 V B) +0.79 VC) +0.11 V D) –0.11 VE) –0.79 V

What is the net cell potential of the electrochemical cellFe/Fe2+||Cu2+/Cu?


A) Al3+ will oxidize Cr but not Ca.B) Al3+ will oxidize Ca but not Cr.C) Ca2+ will oxidize Cr but not Al.D) Ca2+ will oxidize Al but not Cr.E) Cr3+ will oxidize Al but not Ca.


A) decreases to zeroB) decreases somewhatC) increases somewhatD) increases a large amountE) remains the same

40. As the reaction in an electrochemical cell approachesequilibrium, the rate of the anode reaction

41. What is the net potential (E°) for this reaction atequilibrium?

2 Fe3+ + 2 I– «2 Fe2+ + I2

A) 0.00 volts B) 0.23 voltsC) 1.00 volts D) 1.31 voltsE) 2.08 volts

A) less than –1 B) between 0 and –1C) 0 D) between 0 and 1E) greater than 1

42. In order for a redox reaction to be at equilibrium, thepotential (E°) must be

A) less than 0 B) 0C) between 0 and 1 D) 1E) greater than 1

43. What is the potential (E°) of an electrochemical cellwhich has reached equilibrium?

A) increasesB) decreasesC) remains the sameD) increases, then decreasesE) decreases, then increases

44. As the reaction in an electrochemical cell approachesequilibrium, the voltage of the cell


A) +0.47 B) +0.21 C) 0.00 D) –0.21 E) –0.47

What is the cell potential, Eº, at equilibrium for the cell:

Pb/Pb2+||Cu2+/Cu?

A) Cr B) PbC) Cr(NO3)2 D) Pb(NO3)2

E) NO3–

46. Which substance is oxidized?

2 Cr + 3 Pb(NO3)2 ® 2 Cr(NO3)2 + 3 Pb

A) Chlorine, Cl2

B) Hydrogen, H2

C) Zinc chloride, ZnCl2

D) Hydrogen chloride, HClE) Oxygen, O2

47. What gas is released when a piece of zinc, Zn, is addedto a hydrochloric acid solution, HCl(aq)?

A) NO2

B) PbO2

C) Pb(NO3)2

D) NO3–

E) This is not a redox reaction

48. Which substance is oxidized?

Pb(NO3)2 ®PbO2 + 2 NO2

A) I2

B) IO3–

C) SO42–

D) HSO3–


49. Which substance is reduced?

5 HSO3– + 2 IO3– ® 5 SO42– + I2 + 3 H+ + H2O

A) the anodeB) the cathodeC) in acid solutionD) in melted copperE) the positive electrode

50. To electroplate copper on a carbon rod, the carbon rodmust be

51.

A) Sn4+(aq) B) Sn2+(aq)C) Al3+(aq) D) Al(s)E) Sn(s)

Which is the strongest oxidizing agent?

A) H2(g)B) HCl(aq)C) Mg(s)D) MgCl2(aq)E) This is not a redox reaction

52. Which is the reduced substance

Mg(s) + 2 HCl(aq) ® MgCl2(aq) + H2(g)

A) Cl2

B) I2

C) KClD) KIE) This is not a redox reaction

53. Which is the substance that is oxidized?

2 KI(aq) + Cl2(aq) ® 2 KCl(aq) + I2(aq)

A) FeCl2(aq)B) FeCl3(aq)C) H2(g)D) SnCl2(aq)E) This is not a redox reaction

54. Which is the substance which is reduced?

SnCl2(aq) + 2 FeCl3(aq) ® 2 FeCl2(aq) + SnCl4(aq)

A) Cr B) PbC) Cr(NO3)2 D) Pb(NO3)2

E) NO3–

55. Which substance is reduced?

2 Cr + 3 Pb(NO3)2 ®2 Cr(NO3)2 + 3 Pb

A) HBr + H2SO4 ® Br2 + SO2 + H2OB) 2 HBr + H2SO4 ® Br2 + SO2 + 2 H2OC) 2 HBr + 2 H2SO4 ® Br2 + 2 SO2 + 4 H2OD) 4 HBr + H2SO4 ® 2 Br2 + SO2 + 2 H2OE) 4 HBr + H2SO4 ® 2 Br2 + SO2 + 2 H2O + 8e–

56. Which reaction is balanced?

57.

A) Cu + MnO4– + H+ ® Cu2+ + Mn2+ + H2OB) Cu + MnO4– + 8 H+ ® Cu2+ + Mn2+ + 4 H2OC) 5Cu + MnO4– + 8 H+ ® 5 Cu2+ + Mn2+ + 4 H2OD) 5Cu + 2 MnO4– + 16 H+ ® 5 Cu2+ + 2 Mn2+ +

8 H2OE) 5Cu + 2 MnO4– + 16 H+ ® 5 Cu2+ + 2 Mn2+ + 8

H2O + 10e–

Which reaction is balanced?

A) Ag + 2 HNO3 ® AgNO3 + NO + H2OB) Ag + 4 HNO3 ® AgNO3 + 7 NO + 2H2OC) 3 Ag + 4 HNO3 ® 3 AgNO3 + NO + 2 H2OD) Ag + 2 HNO3 ® AgNO3 + NO + 2 H2OE) 3 Ag + 4 HNO3 ® 3 AgNO3 + NO + 2 H2O + 3e–

58. Which is correctly balanced?

A) Pb + Cr2O72– + H+ ® Pb2+ + Cr3+ + H2OB) Pb + Cr2O72– + 14 H+ ® Pb2+ + 2Cr3+ + 7 H2OC) Pb + Cr2O72– + H+ + 6e– ® Pb2+ + Cr3+ + H2OD) 2 Pb + Cr2O72– + 14 H+ ® 2 Pb2+ + 2 Cr3+ + 7 H2

OE) 3 Pb + Cr2O72– + 14 H+ ® 3 Pb2+ + 2 Cr3+ + 7

H2O

59. Consider the unbalanced redox equation skeleton.

Pb + Cr2O72– + H+ ® Pb2+ + Cr3+ + H2O

Which is the balanced overall reaction?

A) Pb ® Pb2+ + 2e–

B) Pb2+ + 2e– ® PbC) 2Cr3+ + 7H2O ® Cr2O72– + 14H+ + 6e–

D) Cr2O72– + 14H+ + 6e– ® 2Cr3+ + 7H2OE) Cr2O72– + 6e– ® 2Cr3+ + 7O2–


Pb + Cr2O72– + H+ ® Pb2+ + Cr3+ + H2O

Which is the balanced reduction reaction?

A) Pb ® Pb2+ + 2e–

B) Pb2+ + 2e– ® PbC) 2Cr3+ + 7H2O ® Cr2O72– + 14H+ + 6e–

D) Cr2O72– + 14H+ + 6e– ® 2Cr3+ + 7H2OE) Cr2O72– + 6e– ® 2Cr3+ + 7O2–


Pb + Cr2O72– + H+ ® Pb2+ + Cr3+ + H2O

Which is the balanced oxidation reaction?

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

62. What is the coefficient of phosphorus, P, when theequation is balanced using small whole numbers? H2SO4 + P ® H3PO4 + H2O + SO2

A) 11/2 B) 2 C) 2 1/2 D) 2/5 E) 4/5

63. How many moles of zinc, Zn, will reduce one mole ofvanadium from V5+ to V2+? The unbalanced expressionis

V5+(aq) + Zn(s) ® V2+(aq) + Zn2+(aq)

A) H2OB) NaOHC) H2SO4

D) Na2SO4


64. Which substance is reduced? 2 NaOH + H2SO4 ®Na2SO4 + 2 H2O

A) H2OB) NaOHC) H2SO4

D) Na2SO4


65. Which substance is oxidized? 2 NaOH + H2SO4 ®Na2SO4 + 2 H2O

A) BaSO4 ® Ba2+ + SO42–

B) Cu(NO3)2 + H2S ® CuS + 2 HNO3

C) CaCO3 ® CaO + CO2

D) 2 Al + 6 H2O ® 2 Al(OH)3 + 3 H2

E) NH4+ ® H+ + NH3

66. Which is a redox reaction?

67. A 1.0 M solution of NiBr2 is electrolyzed. Which arethe correct half–reactions?

A) Anode: Br2 + 2e– ® 2 Br– Cathode: Ni ® Ni2+

+ 2e–

B) Anode: 2 Br– ® Br2 + 2e– Cathode: 2 H2O + 2e– ® H2 + 2 OH–

C) Anode: 2 H2O ® O2 + 4 H+ + 4e– Cathode: 2Ni2+ + 4e– ® 2 Ni

D) Anode: 2 H2O ® O2 + 4 H+ + 4e– Cathode: 4 H2O + 4e– ® 2 H2 + 4 OH–

E) Anode: 2 Br– ® Br2 + 2e– Cathode: Ni2+ + 2e– ® Ni

68. A 1.0 M solution of ZnCl2 is electrolyzed. Which arethe correct half–reactions?

A) Anode: 2 Cl– ® Cl2 + 2e– Cathode: Zn2+ + 2e–

® ZnB) Anode: 2 Cl– ® Cl2 + 2e– Cathode: 2 H2O + 2e

– ® H2 + 2 OH–

C) Anode: 2 H2O ® O2 + 4 H+ + 4e– Cathode: 2Zn2+ + 4e– ® 2 Zn


E) Anode: Cl2 + 2e– ® 2 Cl– Cathode: Zn ® Zn2+ + 2e–

A) Anode: 2 Cl– ® Cl2 + 2e– Cathode: 2 Na+ +2e– ® 2 Na

B) Anode: 2 Cl– ® Cl2 + 2e– Cathode: 2 H2O + 2e– ® H2 + 2 OH–

C) Anode: 2 H2O ® O2 + 4 H+ + 4e– Cathode: 4Na+ + 4e– ® 4 Na


E) Anode: Cl2 + 2e– ® 2 Cl– Cathode: 2 Na ® 2Na+ + 2e–

69. What are the anode and cathode half–reactions for theelectrolysis of fused (melted) NaCl?

A) Anode: 2 H2O ® O2 + 4 H+ + 4e– Cathode: 4K+ + 4e– ® 4 K

B) Anode: 2 Br– ® Br2 + 2e– Cathode: 2 H2O +2e– ® H2 + 2 OH–

C) Anode: Br2 + 2e– ® 2 Br– Cathode: 2 K ® 2K+ + 2e–


E) Anode: 2 Br– ® Br2 + 2e– Cathode: 2 K+ + 2e– ® 2 K

70. What are the anode and cathode reactions during theelectrolysis of fused KBr?

A) is exothermicB) produces an electric currentC) uses an applied electric currentD) involves oxidation and reduction reactionsE) occurs spontaneously

71. An electrolytic cell differs from a chemical (or voltaic)cell in that the electrolytic cell

A) 56Fe3+ B) 108Ag+

C) 112Cd2+ D) 197Au3+

E) 207Pb2+

72. One mole of electrons is passed through aqueoussystems containing the stated ion and two inertelectrodes. Which will have the greatest mass ofdeposited element?

A) 0.12 B) 0.24 C) 2.4 D) 4.8 E) 12

73. Given the equation:

Mg2+(aq) + 2 Cl–(aq) ® Mg(s) + Cl2(l)

How many grams of magnesium metal are produced bythe electrolysis of 0.10 mole of melted magnesiumchloride, MgCl2 ?

A) (+), oxidationB) (+), reductionC) (–), reductionD) (–), oxidationE) reactions only occur at the cathode

74. What is the charge and the reaction occurring at theanode of an electrolysis reaction?

A) CaB) Ca2+

C) Cl–

D) Cl2

E) Oxidation does not occur

75. In the electrolysis of molten CaCl2 , the speciesoxidized is

A) 2.00 grams B) 2.52 gramsC) 3.00 grams D) 79.9 gramsE) 159 grams

76. In the electrolysis of aqueous copper (II) bromidesolution, CuBr2(aq), 1.00 gram of Cu is deposited at thecathode. How many grams of bromine are formed at theanode?

A) in the wire B) at the anodeC) at the cathode D) at the salt bridgeE) in solution

77. Electroplating always takes place

A) (–), oxidationB) (+), oxidationC) (–), reductionD) (+), reductionE) no reaction occurs at the cathode

78. At the cathode during electrolysis, what is its chargeand what type of reaction occurs.

A) at the wire B) at the anodeC) at the cathode D) at the salt bridgeE) in solution

79. Electroplating occurs during electrolysis

A) radius of the cationB) activity of the metalC) temperature of the electrolyteD) quantity of electrical charge passed through the

cellE) molarity of the ions in solution

80. The mass of a metal deposited at the cathode duringelectroplating is proportional to the

A) reduced at the negative electrodeB) reduced at the positive electrodeC) oxidized at the negative electrodeD) oxidized at the positive electrodeE) neither oxidized nor reduced

81. If fused silver chloride, AgCl, is electrolyzed, the Ag+

ions are

A) 207Pb2+ B) 108Ag+

C) 59Ni2+ D) 56Fe2+

E) 27Al3+

82. From which aqueous system will one mole of electronsdeposit the greatest mass of the element ?

A) 15.9 g B) 31.8 gC) 47.7 g D) 63.5 gE) 127 g

83. How many grams of copper metal are deposited from asolution of copper (II) sulfate, CuSO4 , by 0.500 moleof electrons?

Answer KeyAP Chemistry Electrochemistry Review

1. C2. C3. D4. B5. B6. D7. C8. A9. D10. C11. A12. D13. A14. E15. B16. C17. B18. D19. B20. C21. A22. C23. A24. D25. A26. C27. C28. D29. D30. B31. D32. C33. A34. D35. E36. E

37. C38. B39. B40. B41. A42. C43. B44. B45. C46. A47. B48. C49. B50. B51. A52. B53. D54. B55. D56. B57. D58. C59. E60. D61. A62. B63. A64. E65. E66. D67. E68. C69. A70. E71. C72. B

73. C74. A75. C76. B77. C78. C79. C80. D81. A82. B83. A

1.which half–cell reaction correctly represents ... · 26.base your answer on the table below....

Documents