Redox Review Ms. MosleyChem II

A) 0 B) –2 C) –4 D) +4

1. What is the sum of the oxidation numbers of theatoms in the compound CO2?

A) P4O10 B) PCl5

C) Ca3(PO4)2 D) KH2PO3

2. In which substance does phosphorus have a +3oxidation state?

A) +1 B) –1 C) +7 D) –7

3. What is the oxidation number of iodine in KIO4?

A) 0 to +2 B) 0 to –2C) +2 to 0 D) –2 to 0

4. Given the reaction that occurs in an electrochemicalcell:

Zn(s) + CuSO4(aq) ZnSO4(aq) + Cu(s)

During this reaction, the oxidation number of Znchanges from

A) chromate ion B) oxalate ionC) phosphate ion D) thiocyanate ion

5. Which polyatomic ion has a charge of 3–?

A) –2 B) +2 C) –4 D) +4

6. What is the oxidation number of Pt in K2PtCl6?

A) CO B) CO2 C) CCl4 D) CH4

7. In which compound does carbon have an oxidationstate of –4?

A) Cl2 B) HClC) HClO D) HClO2

8. In which substance does chlorine have an oxidationnumber of +1?

A) +12 B) +2 C) +3 D) +6

9. What is the oxidation number of chromium in K2Cr2O7 ?

A) The oxidation half-reaction and the reductionhalf-reaction occur simultaneously.

B) The oxidation half-reaction occurs before thereduction half-reaction.

C) The oxidation half-reaction occurs after thereduction half-reaction.

D) The oxidation half-reaction occursspontaneously but the reduction half-reactiondoes not.

10. Which statement correctly describes a redoxreaction?

A) electrons B) neutronsC) protons D) ions

11. When a redox reaction occurs, there must be atransfer of

A) a change in oxidation numberB) a change of phaseC) the transfer of protonsD) the formation of ions

12. A redox reaction always involves

A) It is oxidized by losing electrons.B) It is oxidized by gaining electrons.C) It is reduced by losing electrons.D) It is reduced by gaining electrons.

13. In the reaction

Mg + ZnCI2 ® MgCI2 + Zn,

which is true of the magnesium?

A) The Pt2+ gains electrons and its oxidationnumber increases.

B) The Pt2+ gains electrons and its oxidationnumber decreases.

C) The Pt2+ loses electrons and its oxidationnumber increases.

D) The Pt2+ loses electrons and its oxidationnumber decreases.

14. Which changes occur when Pt2+ is reduced?

A) Al0 B) Cr3+ C) Al3+ D) Cr0

15. In the reaction

Al0 + Cr3+ ® Al3+ + Cr0,

the species oxidized is

A) reduced, and the oxidation number changesfrom +1 to 0

B) reduced, and the oxidation number changesfrom +2 to 0

C) oxidized, and the oxidation number changesfrom 0 to +1

D) oxidized, and the oxidation number changesfrom +1 to 0

16. In the reaction:

Pb + 2 Ag+ ® Pb2+ + 2 Ag,

the Ag+ is

A) Co0 B) Cu0 C) Co2+ D) Cu2+

17. In the reaction

Co0 + Cu2+ ® Co2+ + Cu0,

which specie is reduced?

A) electron B) ionC) neutron D) proton

18. The transfer of which particle is required for a redoxreaction to occur?

A) Zn0 B) Ag0 C) Zn2+ D) Ag+

19. What species is reduced in the reaction below?

Zn0 + 2 Ag+ ® Zn2+ + 2 Ag0?

A) Ag+ B) Ag C) Pb D) Pb2+

20. In the reaction

Pb + 2 Ag+ ® Pb2+ + 2 Ag,

the oxidizing agent is

A) –1 to –3 B) –2 to –1C) 3 to –1 D) 4 to –3

21. The oxidation number of a reducing agent canchange from

A) Zn2+ B) Mg2+ C) Co2+ D) Ca2+

22. Which ion is most easily reduced?

A) Fe2+ B) Cl2 C) Fe3+ D) Cl–

23. Which is the oxidizing agent in the reaction

2 Fe2+ + Cl2 ® 2 Fe3+ + 2 Cl– ?

A) loses protonsB) gains protonsC) acts as an oxidizing agentD) acts as a reducing agent

24. When a substance is oxidized, it

A) Mg + 2e– Mg2+

B) Cl2 + 2e– 2Cl–

C) Mg Mg2+ + 2e–

D) Cl2 2Cl– + 2e–

25. In the reaction Mg + Cl2 MgCl2, the correcthalf-reaction for the oxidation that occurs is

A) C(s) B) H+

C) C2+ D) H2(g)

26. Given the equation:

C(s) + H2O(g) CO(g) + H2(g)Which species undergoes reduction?

A) Fe(s) ® Fe2+(aq) + 2e–

B) Fe(s) + 2e– ® Fe2+(aq)C) Cu2+ (aq) ® Cu(s) + 2e–

D) Cu2+(aq) + 2e– ® Cu(s)

27. Given the reaction:

Fe(s) + Cu2+ (aq) ® Fe2+(aq) + Cu(s)

Which half-reaction correctly shows the oxidationthat occurs?

A) Each Al loses 2e– and each Cu2+ gains 3e–.B) Each Al loses 3e– and each Cu2+ gains 2e–.C) Each Al3+ gains 2e– and each Cu loses 3e–.D) Each Al3+ gains 3e– and each Cu loses 2e–.

28. Given the balanced equation representing a redoxreaction:

2Al + 3Cu2+ ® 2Al3+ + 3Cu

Which statement is true about this reaction?

A) Fe2+ ®Fe3+ + e– B) Fe2+ + 2e– ® FeC) Fe3+ + e– ® Fe2+ D) Fe ® Fe2+ + 2e–

29. Which half-reaction equation represents thereduction of an iron(II) ion?

A) Al + 3e– Al3+ B) Al Al3+ + 3e–

C) O2+ 4e– 2 O2– D) O2 2 O2– + 4e–

30. Given the reaction for the corrosion of aluminum:

4 Al + 3 O2 2 Al2O3Which half-reaction correctly represents theoxidation that occurs?

A) Zn(s) ® Zn2+ + 2e–

B) 2 H + 2e– ® H2(g)C) Zn2+ + 2e ® Zn(s)D) 2 Cl– ® Cl2(g) + 2e–

31. Given the reaction:

Zn(s) + 2 HCl(aq) ® ZnCl2(aq) + H2(g)

Which equation represents the correct oxidationhalf-reaction?

A) It undergoes reduction and its oxidation numberdecreases.

B) It undergoes reduction and its oxidation numberincreases.

C) It undergoes oxidation and its oxidation numberdecreases.

D) It undergoes oxidation and its oxidation,number increases.

32. Given the reaction:

Cu(s) + 4 HNO3(aq) Cu(NO3)2(aq) + 2 NO2(g) +2 H2O( )

As the reaction occurs, what happens to copper?

A) 2 Na0 ® 2 Na+ + 2e–

B) 2 Cl– ® Cl20 + 2e–

C) 2 H+ + 2e– ® H20

D) O20 + 2e– ® 2 O–2

33. Given the reaction:

2 NaCl + 2 H2O ® 2 NaOH + H2 + Cl2

Which electronic equation correctly represents theoxidation that occurs in this reaction?

A) 6 B) 2 C) 3 D) 8

34. Given the reaction:

2 Al0(s) + 3 Ni2+ (aq) ® 2 Al3+(aq) + 3 Ni0(s)

What is the total number of moles of electronslost by 2 moles of Al0(s)?

A) Atoms of Zn(s) lose electrons and are oxidized.B) Atoms of Zn(s) gain electrons and are reduced.C) There is a net loss of mass.D) There is a net gain of mass.

35. Given the reaction:

Zn(s) + 2 HCl(aq) ZnCl2(aq) + H2(g)

Which statement correctly describes what occurswhen this reaction takes place in a closed system?

A) 2 Na+ + S2– ® Na2SB) H+ + C2H3O2– ® HC2H3O2

C) NH3 + H+ + Cl– ® NH4+ + ClD) Cu + 2 Ag+ + 2 NO3– ® 2 Ag + Cu2+ +

2 NO3–

36. Which equation represents a redox reaction?

A)B)C)D)

37. Which equation represents an oxidation-reductionreaction?

A) 2Ca(s) + O2 (g) ® 2CaO(s)B) AgNO3 (aq) + KCl(aq) ®

AgCl(s) + KNO3 (aq)C) HCl(aq) + NaOH(aq) ®

NaCl(aq) + H2O( )D) H3O+ (aq) + OH– (aq) ® 2H2O( )

38. In which reaction are electrons transferred from onereactant to another reactant?

A) AgNO3 + KI ® AgI + KNO3

B) Cu + 2 AgNO3 ® Cu(NO3)2 + 2 AgC) 2 KOH + H2SO4 ® K2SO4 + 2 H2OD) Ba(OH)2 + 2 HCl ® BaCl2 + 2 H2O

39. Which reaction is an example of anoxidation-reduction reaction?

A) Ag B) Au C) Cu D) Pb

40. Which metal is more active than H2?

A) Fe(s) B) Ba(s)C) Pb(s) D) Ag(s)

41. According to Reference Table J, which will reduceMg2+ to Mg(s)?

A) Cu2+ B) Ni2+ C) Fe2+ D) Zn2+

42. Based on the Activity Series,, which ion will oxidizePb to Pb2+?

A) magnesium B) nickelC) copper D) silver

43. Which metal reacts spontaneously with a solutioncontaining zinc ions?

A) Ag B) Au C) Cu D) Mg

44. Under standard conditions, which metal will reactwith 0.1 M HCl to liberate hydrogen gas?

A) Br2 B) F2 C) I2 D) Cl2

45. According to Reference Table J, which halogen willreact spontaneously with Au(s) to produce Au3+?

A) Pb(s) B) Cu(s)C) Hg( ) D) Ag(s)

46. The half-reaction

2 H+(aq) + 2e– ® H2(g)

will occur when H+(aq) reacts with

A) charge but not of massB) mass but not of chargeC) both charge and massD) neither charge nor mass

47. When an equation is correctly balanced, it mustshow conservation of

A) Al3+ + 3e– ® AlB) Al3+ + 3e– ® 3 AlC) Al3+ ® Al + 3e–

D) Al3+ ® 3 Al + 3e–

48. Which half-reaction for the reduction of Al3+ to Al iscorrectly balanced?

A) Cl2 + 2e– ® 2 ClB) Cl2 ® Cl– + 2e–

C) 2 Br– + 2e– ® Br2

D) Br– ® Br2 + 2e–

49. Which half-reaction shows both the conservation ofmass and the conservation of charge?

A) 1, because a total of 6 electrons is transferredB) 2, because a total of 6 electrons is transferredC) 1, because a total of 3 electrons is transferredD) 2, because a total of 3 electrons is transferred

50. Given the unbalanced ionic equation:

When this equation is balanced, both Fe3+ and Fehave a coefficient of

A) Fe ® Fe2+ + e– B) Fe + 2e– ® Fe2+

C) Fe ® Fe2+ + 2e– D) Fe + 2e– ® Fe3+

51. Which equation shows conservation of charge?

A) temperature B) volumeC) matter D) nothing

52. A chemical reaction always demonstrates theconservation of what?

A) Cu + e– ® Cu+ B) Cu2+ + 2e– ® CuC) Cu+ ® Cu + e– D) Cu2+ ® Cu + 2e–

53. Which half-reaction shows conservation of charge?

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

54. When the reaction

is completely balanced using smallest whole numbers, the coefficient of H2O will be

A) Al + 2 H+ ® Al3+ + H2

B) Zn + 2 H+ ® Zn2+ + H2

C) Cr + Ag+ ® Cr3+ + Ag

D) Cu + Ag+ ® Cu2+ + Ag

55. Which redox equation is correctly balanced?

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

56. Given the unbalanced equation:

When the equation is correctly balanced usingsmallest whole numbers, the coefficient of Ag+ is

A) 10 B) 7 C) 5 D) 4

57. Given the reaction:

When the equation is correctly balanced usingsmallest whole numbers, the sum of the coefficientswill be

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

58. Given the unbalanced equation:

When the equation is correctly balanced using smallest whole number coefficients, the coefficient ofHCl is

A) chemical energy to electrical energyB) chemical energy to nuclear energyC) electrical energy to chemical energyD) nuclear energy to electrical energy

59. Which energy conversion occurs in a voltaic cell?

A) PbO2 B) PbSO4

C) H2SO4 D) H2O

60. Which substance functions as the electrolyte in anautomobile battery?

A) Ni2+ + 2e- ® Ni B) Sn + 2e- ®Sn2+

C) Zn ® Zn2+ + 2e- D) Fe3+ ® Fe2+ + e-

61. Which half-reaction can occur at the anode in avoltaic cell?

A) reactant, with decreasing concentration B) reactant, with increasing concentrationC) product, with decreasing concentration D) product, with increasing concentration

62. Given the lead-acid battery reaction:

As the lead-acid battery discharges, sulfuric acid is a

63. Base your answer to the following question on the diagram of the voltaic cell below.

When the switch is closed, in which half-cell does oxidation occur?

A) Oxidation occurs at the anode, only.B) Reduction occurs at the anode, only.C) Oxidation occurs at both the anode and the

cathode.D) Reduction occurs at both the anode and the

cathode.

64. Which statement is true for any electrochemical cell?

A) Both Pb and Pb4+ undergo oxidation.B) Both Pb and Pb4+ undergo reduction.C) Pb is oxidized and Pb4+ is reduced.D) Neither the Pb nor the Pb4+ is oxidized or

reduced.

65. What occurs during discharge in the lead-acidbattery reaction below?

Pb + PbO2 + 2 H2SO4 « 2 PbSO4 + 2 H2O

A) B)C) D)

66. Given the redox reaction:

Which species is oxidized during discharge?

A) is reduced to B) is reduced to C) is oxidized to D) is oxidized to

67. Given the nickel-cadmium battery reaction:

What occurs during discharge in the nickel-cadmium battery?

68. Base your answer to the following question on thediagram of the chemical cell at 298 K and on theequation below.

A) gain electrons B) lose electronsC) gain protons D) lose protons

In the given reaction, the Ag+ ions

A) The concentration of decreases and the number of moles of increases.B) The concentration of decreases and the number of moles of increases.C) The concentration of increases and the number of moles of decreases.D) The concentration of increases and the number of moles of decreases.

69. Given the equation for the overall reaction in a lead-acid storage battery:

Which occurs during the charging of the battery?

A) Ni3+ B) Ni2+ C) Cd D) Cd2+

70. Given the reaction for the nickel-cadmium battery:

2 NiO(OH)3 + Cd + 2 H2O ® 2 Ni(OH)2 +Cd(OH)2Which species is oxidized during the discharge ofthe battery?

A) reduction of CdB) oxidation of CdC) reduction of NiOOHD) oxidation of NiOOH

71. The equation below represents the reaction occurringin a nickel-cadmium battery.

2 NiO(OH)3 + Cd + 2 H2O ® 2 Ni(OH)2 +Cd(OH)2Which reaction occurs at the cathode?

A) Pb(s) to Zn(s)B) Pb2+(aq) to Zn2+(aq)C) Zn(s) to Pb(s)D) Zn2+(aq) to Pb2+(aq)

72. Given the balanced equation representing thereaction occurring in a voltaic cell:Zn(s) + Pb2 +(aq) Zn2 +(aq) + Pb(s)In the completed external circuit, the electrons flowfrom

A) from negative Zn to positive CuB) from positive Zn to negative CuC) from negative Cu to positive ZnD) from positive Cu to negative Zn

73. What is the electron flow in a wire connecting theZn and Cu electrodes of a zinc-copper chemical cellat standard conditions?

A) at the cathode in both an electrolytic cell and avoltaic cell

B) at the cathode in an electrolytic cell and at theanode in a voltaic cell

C) at the anode in both an electrolytic cell and avoltaic cell

D) at the anode in an electrolytic cell and at thecathode in a voltaic cell

74. Where does oxidation occur in an electrochemicalcell?

A) Al(s) to Ni(s)B) Ni(s) to Al(s)C) Al3+(aq) to Ni2+(aq)D) Ni2+(aq) to Al3+(aq)

75. The diagram below represents a chemical cell at 298K.

When the switch is closed, electrons flow from

A) polymerization B) distillationC) electrolysis D) saponification

76. Which procedure requires the use of an externalelectric current to force a redox reaction to occur?

A) A chemical reaction produces an electriccurrent.

B) An electric current produces a chemicalreaction.

C) An oxidation reaction takes place at thecathode.

D) A reduction reaction takes place at the anode.

77. What occurs when an electrolytic cell is used forsilver-plating a spoon?

A) The reaction occurs in a chemical cell andreleases energy.

B) The reaction occurs in a chemical cell andabsorbs energy.

C) The reaction occurs in an electrolytic cell andreleases energy.

D) The reaction occurs in an electrolytic cell andabsorbs energy.

78. Which statement best describes the reactionrepresented by the equation below?

2 NaCl + 2 H2O + electricity ® Cl2 + H2 + 2NaOH

A) chemical energy ® electrical energyB) electrical energy ® chemical energyC) light energy ® heat energyD) light energy ® chemical energy

79. Which energy transformation occurs when anelectrolytic cell is in operation?

A) Ag0 + 1e– ® Ag+ B) Ag0 ® Ag+ + 1e–

C) Ag+ + 1e– ® Ag0 D) Ag+ ® Ag0 + 1e–

80. Which half-reaction occurs at the negative electrodein an electrolytic cell in which an object is beingplated with silver?