1.Which change in oxidation number represents oxidation? 9 ... · A)Sn2+(aq) ®Sn4+(aq) B)Sn2+(aq) ® Sn(s) C)Sn4+(aq) ® Sn2+(aq) D)Sn4+(aq) ® Sn(s) E)Sn(s) ® Sn2–(aq) 1.Which

A) Sn2+(aq) ®Sn4+(aq)B) Sn2+(aq) ® Sn(s)C) Sn4+(aq) ® Sn2+(aq)D) Sn4+(aq) ® Sn(s)E) Sn(s) ® Sn2–(aq)

1. Which change in oxidation number represents oxidation?

A) Sn2+ B) Ag+

C) Sn4+ D) AgE) an unknown catalyst

2. In the reaction

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

the oxidizing agent is:

A) gains electrons and is reduced.B) gains electrons and is oxidized.C) gains electrons but is neither oxidized nor reduced.D) loses electrons and is oxidized.E) loses electrons and is reduced.

3. In the half–reaction Na+ + e– ® Na, the sodium ion

A) Pb2+ ® Pb + 2e– B) Pb2+ + 2e– ® PbC) 2 Br– ® Br2 + 2e– D) 2 Br– + 2e– ® Br2

E) All of these

4. Which equation correctly represents reduction?

A) –10 B) –5 C) +3 D) +10 E) +5

5. The oxidation number of phosphorus in Na4P2O7 is

A) +7 B) +2 C) +3 D) +4 E) +6

6. The oxidation number of carbon in CaC2O4 is

A) +10 B) +2 C) +3 D) +4 E) +5

7. What is the oxidation number of arsenic, As, in diarsenicpentoxide, As2O5?

A) decreased by 1 B) increased by 2C) decreased by 2 D) decreased by 4E) increased by 1

8. C2O42– + MnO2 Mn2+ + 2 CO2

As a result of the above reaction, the oxidation numberof each C atom is

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

9. 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

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

A) 6 B) 2 C) 8 D) 4 E) 10

11. Consider the reaction,

S6+ + ? e– S2–

How many electrons are needed to reduce S6+ to S2–?

A) Cl2 B) Br2 C) Hg2+ D) I2 E) I–

12. Which is the most easily reduced?

A) Au ® Au3+ + 3e–

B) Au + 3e– ® Au3+

C) Au3+ ® Au + 3e–

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

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

A) Cr B) Cr3+

C) Pb D) Pb2+

E) both Cr and Pb

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

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

15. What is the oxidation potential for the reaction?

Cu Cu2+ + 2e–

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

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

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

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

What is the E° for this reaction?

2 Cr 2 Cr3+ + 6e–

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

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

A) PbB) Pb2+

C) ZnD) Zn2+

E) It cannot be determined unless the potentials areknown.

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

Zn/Zn2+||Pb2+/Pb?

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

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.

20. Base your answer on the table below.

Which statement is true?

A) AgB) Al3+

C) LiD) Pb2+

E) MnO4– (acid permanganate)


Which substance will oxidize Fe2+ to Fe3+?

A) 2 Fe3+ + 3 Cd 2 Fe + 3 Cd2+

B) 2 Fe + 3 Cd2+ 2 Fe3++ 3 CdC) 2 Fe+ 3 Cd 2 Fe3+ + 3 Cd2+

D) 2 Fe3+ + 3 Cd2+ 2 Fe + 3 CdE) 2 Fe3+ + 3 Cd2+ Fe2Cd3 + 12e–


According to these data, which reaction takes place?

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.


Which statement is true?

A) Ag is produced.B) no reaction occurs.C) H2 gas is produced.D) NO gas is produced.E) Cu is reduced.


When Cu is placed in an aqueous solution of Ag(NO3)

A) + 2.36 V B) + 1.56 VC) + 0.84 V D) + 0.04 VE) –0.04 V

25. Consider this cell:

What is the maximum voltage developed by this cellwhen the switch is closed?

A) oxidize nickel, Ni.B) oxidize copper, Cu.C) oxidize fluorine gas, F2.D) reduce magnesium ion, Mg2+.E) reduce fluorine gas, F2.


Water can

A) Zinc metal reduces Sn4+ to Sn2+

B) Zinc metal reacts with HNO3 to liberate hydrogengas

C) Zinc metal reacts with HNO3 to liberate NOrather than H2

D) Sn is oxidized to Sn2+ when it reacts with HNO3

E) Sn2+ ions react with HNO3 to liberate NO ratherthan H2

27. STANDARD ELECTRODE POTENTIALSIon Concentrations 1.0 M H2O at 298 K, 1 atm

Which is true?

A) Ag B) AuC) Cl– D) H+ + MnO4–

E) Sn2+


Which species will reduce Cu2+ to Cu?

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?

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

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

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

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

2 Fe3+ + 2 I– 2 Fe2+ + I2

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

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

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

33. Which is the oxidized substance?

Mg(s) + 2 HCl(aq) ® MgCl2(aq) + H2(g)

A) NO2

B) PbO2

C) Pb(NO3)2

D) O2–

E) This is not a redox reaction

34. Which substance is reduced?

Pb(NO3)2 ® PbO2 + 2 NO2

A) Al3+ B) Cl– C) Fe3+ D) Sn2+ E) H+

35. Which ion can act as both an oxidizing agent and areducing agent in 1.0 M aqueous solution?

A) I2

B) IO3–

C) SO42–

D) HSO3–


36. Which substance is reduced?

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

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

37. Consider the unbalanced redox equation skeleton.

Pb + Cr2O72– + H+ ® Pb2+ + Cr3+ + H2O

Which is the balanced overall reaction?

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–

38. Which is correctly balanced?

A) H2OB) NaOHC) H2SO4

D) Na2SO4


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

A) H2OB) NaOHC) H2SO4

D) Na2SO4


40. Which substance is reduced? 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

41. Which is a redox reaction?

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–

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

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

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

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: 2 Zn2+ + 4e– 2 ZnD) Anode: 2 H2O O2 + 4 H+ + 4e–

Cathode: 4 H2O + 4e– 2 H2 + 4 OH–

E) Anode: Cl2 + 2e– 2 Cl–

Cathode: Zn Zn2+ + 2e–

43. A 1.0 M solution of ZnCl2 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: 2 Ni2+ + 4e– 2 NiD) 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

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

A) CaB) Ca2+

C) Cl–

D) Cl2

E) Oxidation does not occur

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

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

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

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

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

48. 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

49. Electroplating occurs during electrolysis

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

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

ions are

A) I is TRUE, II is FALSEB) I is FALSE, II is TRUEC) I and II are BOTH FALSED) I and II are BOTH TRUE but II IS NOT a correct

explanation of IE) I and II are BOTH TRUE and II IS a correct

explanation of I

51. I. Potassium is a good oxidizing agent

BECAUSE

II. potassium is a metal and loses electrons easily.



explanation of I

52. I. Fluorine is a good oxidizing agent

BECAUSE

II. fluorine has a small atomic radius and gains anelectron easily.



explanation of I

53. I. Fluorine acts as an oxidizing agent when it combineswith sodium

BECAUSE

II. fluorine gains electrons in the reaction.



explanation of I

54. I. The oxidation number of Cu in CuSO4 is +2

BECAUSE

II. the oxidation state of sulfur is +4.



explanation of I

55. I. The oxidation number of Pb in PbSO4 is +4

BECAUSE

II. the oxidation state of sulfur is also +4.



explanation of I

56. I. Iodine is a better oxidizing agent than fluorine

BECAUSE

II. Iodine has a greater electronegativity value.



explanation of I

57. I. Fluorine is the best reducing agent

BECAUSE

II. when a species is reduced, it gains electrons.

Answer KeyRedox Practice 2

1. A2. B3. A4. B5. E6. C7. E8. E9. B10. D11. C12. A13. D14. C15. B16. B17. B18. C19. A20. B21. E22. A23. B24. A25. B26. E27. C28. E29. C30. B31. A32. C33. C34. C35. D36. B

37. E38. C39. E40. E41. D42. E43. C44. E45. C46. A47. B48. C49. C50. A51. B52. E53. E54. A55. C56. C57. B

Documents

1.Which change in oxidation number represents oxidation? 9 ... · A)Sn2+(aq) ®Sn4+(aq) B)Sn2+(aq) ® Sn(s) C)Sn4+(aq) ® Sn2+(aq) D)Sn4+(aq) ® Sn(s) E)Sn(s) ® Sn2–(aq) 1.Which