Sn 2+ (aq) + 2 Ag + (aq) Sn 4+ (aq) + 2 Ag(s),

Transcription

1 1. Which change in oxidation number represents oxidation? A) Sn 2+ (aq) Sn 4+ (aq) B) Sn 2+ (aq) Sn(s) C) Sn 4+ (aq) Sn 2+ (aq) D) Sn 4+ (aq) Sn(s) E) Sn(s) Sn 2 (aq) 2. In the reaction Sn 2+ (aq) + 2 Ag + (aq) Sn 4+ (aq) + 2 Ag(s), the oxidizing agent is: A) Sn 2+ B) Ag + C) Sn 4+ D) Ag E) an unknown catalyst 3. In the half reaction Na + + e Na, the sodium ion 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. 4. Which equation correctly represents reduction? A) Pb 2+ Pb + 2e B) Pb e Pb C) 2 Br Br2 + 2e D) 2 Br + 2e Br2 E) All of these 5. The oxidation number of phosphorus in Na4P2O7 is A) 10 B) 5 C) +3 D) +10 E) The oxidation number of carbon in CaC2O4 is A) +7 B) +2 C) +3 D) +4 E) What is the oxidation number of arsenic, As, in diarsenic pentoxide, As2O5? A) +10 B) +2 C) +3 D) +4 E) C2O4 2 + MnO2 Mn CO2 As a result of the above reaction, the oxidation number of each C atom is A) decreased by 1 B) increased by 2 C) decreased by 2 D) decreased by 4 E) increased by 1 9. The function of the salt bridge in an electrochemical cell is to A) increase the cell voltage B) maintain electrical neutrality C) increase the oxidation reduction rate D) supply a travel pathway for electrons E) increase the rate of attainment of equilibrium 10. In the half cell reaction Ca Ca e, which is true of the calcium atom? A) It gains protons B) It loses protons C) It gains electrons D) It loses electrons E) It loses an electron and gains a proton 11. Consider the reaction, S 6+ +? e S 2 How many electrons are needed to reduce S 6+ to S 2? A) 6 B) 2 C) 8 D) 4 E) Which is the most easily reduced? A) Cl2 B) Br2 C) Hg 2+ D) I2 E) I 13. Which half-reaction would occur at the cathode of an electrochemical cell? A) Au Au e B) Au + 3e Au 3+ C) Au 3+ Au + 3e D) Au e Au E) Au + Au 3+ 3e + Au 3+

2 14. Which substance is the electrode that gains weight during the operation of this electrochemical cell? Cr/Cr 3+ Pb 2+ /Pb 17. For the following question refer to the table below. A) Cr B) Cr 3+ C) Pb D) Pb 2+ E) both Cr and Pb 15. What is the oxidation potential for the reaction? Cu Cu e A) V B) V C) V D) V E) V 16. What is the electrode potential of the standard hydrogen half-cell reaction? What is the E for this reaction? 2 Cr 2 Cr e A) V B) V C) 0.00 V D) 0.74 V E) 1.48 V 18. In an electrochemical cell, the positive ions go from the A) anode to the cathode through the wire B) cathode to the anode through the wire C) anode to the cathode through the salt bridge D) cathode to the anode through the salt bridge E) cathode to the anode through the wire and anode to the cathode through the salt bridge 19. To which electrode do the electrons move in the cell Zn/Zn 2+ Pb 2+ /Pb? A) Pb B) Pb 2+ C) Zn D) Zn 2+ E) It cannot be determined unless the potentials are known. A) V B) 0.00 V C) V D) V E) V

3 20. Base your answer on the table below. 22. Base your answer on the table below. Which statement is true? A) Br2 will oxidize the chloride ion, but not the iodide ion. B) Br2 will oxidize the iodide ion, but not the chloride ion. C) I2 will oxidize the chloride ion, but not the bromide ion. D) I2 will oxidize the chloride ion, but not the bromide ion. E) Cl2 will oxidize the bromide ion, but not the iodide ion. 21. Base your answer on the table below. According to these data, which reaction takes place? A) 2 Fe Cd 2 Fe + 3 Cd 2+ B) 2 Fe + 3 Cd 2+ 2 Fe Cd C) 2 Fe+ 3 Cd 2 Fe Cd 2+ D) 2 Fe Cd 2+ 2 Fe + 3 Cd E) 2 Fe Cd 2+ Fe2Cd3 + 12e 23. Base your answer on the table below. Which substance will oxidize Fe 2+ to Fe 3+? A) Ag B) Al 3+ C) Li D) Pb 2+ E) MnO4 (acid permanganate) Which statement is true? A) Al 3+ will oxidize Cr but not Ca. B) Al 3+ will oxidize Ca but not Cr. C) Ca 2+ will oxidize Cr but not Al. D) Ca 2+ will oxidize Al but not Cr. E) Cr 3+ will oxidize Al but not Ca. 24. Base your answer on the table below. When Cu is placed in an aqueous solution of Ag(NO3) A) Ag is produced. B) no reaction occurs. C) H2 gas is produced. D) NO gas is produced. E) Cu is reduced.

4 25. Consider this cell: 27. STANDARD ELECTRODE POTENTIALS Ion Concentrations 1.0 M H2O at 298 K, 1 atm Which is true? What is the maximum voltage developed by this cell when the switch is closed? A) V B) V C) V D) V E) 0.04 V 26. Base your answer on the table below. A) Zinc metal reduces Sn 4+ to Sn 2+ B) Zinc metal reacts with HNO3 to liberate hydrogen gas C) Zinc metal reacts with HNO3 to liberate NO rather than H2 D) Sn is oxidized to Sn 2+ when it reacts with HNO3 E) Sn 2+ ions react with HNO3 to liberate NO rather than H2 28. Base your answer on the table below. Water can A) oxidize nickel, Ni. B) oxidize copper, Cu. C) oxidize fluorine gas, F2. D) reduce magnesium ion, Mg 2+. E) reduce fluorine gas, F2. Which species will reduce Cu 2+ to Cu? A) Ag B) Au C) Cl D) H + + MnO4 E) Sn 2+

5 29. Base your answer on the table below. 33. Which is the oxidized substance? Mg(s) + 2 HCl(aq) MgCl2(aq) + H2(g) What is the net potential developed by an electrochemical cell with these half reactions? A) V B) V C) V D) 0.63 V E) 0.89 V 30. As the reaction in an electrochemical cell approaches equilibrium, the rate of the anode reaction A) decreases to zero B) decreases somewhat C) increases somewhat D) increases a large amount E) remains the same 31. What is the net potential (E ) for this reaction at equilibrium? 2 Fe I 2 Fe 2+ + I2 A) H2(g) B) HCl(aq) C) Mg(s) D) MgCl2(aq) 34. Which substance is reduced? Pb(NO3)2 PbO2 + 2 NO2 A) NO2 B) PbO2 C) Pb(NO3)2 D) O Which ion can act as both an oxidizing agent and a reducing agent in 1.0 M aqueous solution? A) Al 3+ B) Cl C) Fe 3+ D) Sn 2+ E) H Which substance is reduced? 5 HSO3 + 2 IO3 5 SO4 2 + I2 + 3 H + + H2O A) 0.00 volts B) 0.23 volts C) 1.00 volts D) 1.31 volts E) 2.08 volts 32. In order for a redox reaction to be at equilibrium, the potential (E ) must be A) less than 1 B) between 0 and 1 C) 0 D) between 0 and 1 E) greater than 1 A) I2 B) IO3 C) SO4 2 D) HSO3 37. Consider the unbalanced redox equation skeleton. Pb + Cr2O7 2 + H + Pb 2+ + Cr 3+ + H2O Which is the balanced overall reaction? A) Pb + Cr2O7 2 + H + Pb 2+ + Cr 3+ + H2O B) Pb + Cr2O H + Pb Cr H2O C) Pb + Cr2O7 2 + H + + 6e Pb 2+ + Cr 3+ + H2O D) 2 Pb + Cr2O H + 2 Pb Cr H2 O E) 3 Pb + Cr2O H + 3 Pb Cr H2O

6 38. Which is correctly balanced? A) Ag + 2 HNO3 AgNO3 + NO + H2O B) Ag + 4 HNO3 AgNO3 + 7 NO + 2H2O C) 3 Ag + 4 HNO3 3 AgNO3 + NO + 2 H2O D) Ag + 2 HNO3 AgNO3 + NO + 2 H2O E) 3 Ag + 4 HNO3 3 AgNO3 + NO + 2 H2O + 3e 39. Which substance is oxidized? 2 NaOH + H2SO4 Na2SO4 + 2 H2O A) H2O B) NaOH C) H2SO4 D) Na2SO4 40. Which substance is reduced? 2 NaOH + H2SO4 Na2SO4 + 2 H2O A) H2O B) NaOH C) H2SO4 D) Na2SO4 41. Which is a redox reaction? A) BaSO4 Ba 2+ + SO4 2 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 42. What are the anode and cathode reactions during the electrolysis of fused KBr? A) Anode: 2 H2O O2 + 4 H + + 4e Cathode: 4 K + + 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 2 K + + 2e D) Anode: 2 H2O O2 + 4 H + + 4e Cathode: 4 H 2O + 4e 2 H2 + 4 OH E) Anode: 2 Br Br2 + 2e Cathode: 2 K + + 2e 2 K 43. A 1.0 M solution of ZnCl2 is electrolyzed. Which are the correct half reactions? A) Anode: 2 Cl Cl2 + 2e Cathode: Zn e Zn B) Anode: 2 Cl Cl2 + 2e Cathode: 2 H2O + 2e H2 + 2 OH C) Anode: 2 H2O O2 + 4 H + + 4e Cathode: 2 Zn e 2 Zn D) Anode: 2 H2O O2 + 4 H + + 4e Cathode: 4 H2O + 4e 2 H2 + 4 OH E) Anode: Cl2 + 2e 2 Cl Cathode: Zn Zn e 44. A 1.0 M solution of NiBr2 is electrolyzed. Which are the correct half reactions? A) Anode: Br2+ 2e 2 Br Cathode: Ni Ni e B) Anode: 2 Br Br2 + 2e Cathode: 2 H2O + 2e H2 + 2 OH C) Anode: 2 H2O O2 + 4 H + + 4e Cathode: 2 Ni e 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: Ni e Ni 45. In the electrolysis of molten CaCl2, the species oxidized is A) Ca B) Ca 2+ C) Cl D) Cl2 E) Oxidation does not occur

7 46. What is the charge and the reaction occurring at the anode of an electrolysis reaction? A) (+), oxidation B) (+), reduction C) ( ), reduction D) ( ), oxidation E) reactions only occur at the cathode 47. In the electrolysis of aqueous copper (II) bromide solution, CuBr2(aq), 1.00 gram of Cu is deposited at the cathode. How many grams of bromine are formed at the anode? A) 2.00 grams B) 2.52 grams C) 3.00 grams D) 79.9 grams E) 159 grams 48. At the cathode during electrolysis, what is its charge and what type of reaction occurs. A) ( ), oxidation B) (+), oxidation C) ( ), reduction D) (+), reduction E) no reaction occurs at the cathode 49. Electroplating occurs during electrolysis A) at the wire B) at the anode C) at the cathode D) at the salt bridge E) in solution 50. If fused silver chloride, AgCl, is electrolyzed, the Ag + ions are A) reduced at the negative electrode B) reduced at the positive electrode C) oxidized at the negative electrode D) oxidized at the positive electrode E) neither oxidized nor reduced 51. I. Potassium is a good oxidizing agent II. potassium is a metal and loses electrons easily. 52. I. Fluorine is a good oxidizing agent II. fluorine has a small atomic radius and gains an electron easily. 53. I. Fluorine acts as an oxidizing agent when it combines with sodium II. fluorine gains electrons in the reaction.

8 54. I. The oxidation number of Cu in CuSO4 is +2 II. the oxidation state of sulfur is I. Iodine is a better oxidizing agent than fluorine II. Iodine has a greater electronegativity value. 55. I. The oxidation number of Pb in PbSO4 is +4 II. the oxidation state of sulfur is also I. Fluorine is the best reducing agent II. when a species is reduced, it gains electrons.

9 Answer Key Redox Practice 2 1. A 2. B 3. A 4. B 5. E 6. C 7. E 8. E 9. B 10. D 11. C 12. A 13. D 14. C 15. B 16. B 17. B 18. C 19. A 20. B 21. E 22. A 23. B 24. A 25. B 26. E 27. C 28. E 29. C 30. B 31. A 32. C 33. C 34. C 35. D 36. B 37. E 38. C 39. E 40. E 41. D 42. E 43. C 44. E 45. C 46. A 47. B 48. C 49. C 50. A 51. B 52. E 53. E 54. A 55. C 56. C 57. B