Chapter 19 Review Student: ___________________________________________________________________________ 1. Complete and balance the following redox equation. When properly balanced using the smallest whole-number coefficients, the coefficient of S is H2S + HNO3 → S + NO (acidic solution) A. 1 B. 2 C. 3 D. 5 E. 6 2. 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 3. Complete and balance the following redox equation. What is the coefficient of H2O when the equation is balanced with the set of smallest whole-number coefficients? H2O +MnO4- + I- →MnO2 + IO3- (basic solution) A. 1 B. 2 C. 4 D. 10 E. none of these 4. Complete and balance the following redox equation. Br2 → BrO3- + Br- (basic solution) The sum of the smallest whole-number coefficients is A. 9. B. 12. C. 18. D. 21. E. none of these. 5. 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) → H (g) + 2Ag(s) 2 B. H (g) + 2Ag(s) → H+(aq) + 2Ag+(aq) 2 C. 2H+(aq) + 2Ag(s) → H (g) + 2Ag+(aq) 2 D. H (g) + Ag+(aq) → H+(aq) + Ag(s) 2 E. H (g) + 2Ag+(aq) → 2H+(aq) + 2Ag(s) 2 6. Consider an electrochemical cell constructed from the following half cells, linked by an external circuit and by a KCl salt bridge. • an Al(s) electrode in 1.0 M Al(NO3)3 solution • a Pb(s) electrode in 1.0 M Pb(NO3)2 solution The balanced overall (net) cell reaction is A. Pb(s) + Al3+(aq) → Pb2+(aq) + Al(s). B. 3Pb(s) + 2Al3+(aq) → 3Pb2+(aq) + 2Al(s). C. 3Pb2+(aq) + 2Al(s) → 3Pb(s) + 2Al3+(aq). D. Pb2+(aq) + Al(s) → Pb(s) + Al3+(aq). 7. 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 Sn electrode in 1.0 M Sn(NO3 )2 solution When the cell is running spontaneously, which choice includes only true statements and no false ones? A. The tin electrode loses mass and the tin electrode is the cathode. B. The tin electrode gains mass and the tin 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. E. The iron electrode gains mass and the iron electrode is the cathode. 8. Calculate the value of E°cell for the following reaction: 2Au(s) + 3Ca2+(aq) → 2Au3+(aq) + 3Ca(s) A. -4.37 V B. -1.37 V C. -11.6 V D. 1.37 V E. 4.37 V 9. 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 10. Calculate the standard cell emf for the following cell: Mg |Mg2+ || NO3- (acid soln)| NO(g) | Pt A. 3.33 V B. 1.41 V C. -1.41 V D. 8.46 V E. -8.46 V 11. According to the following cell diagram, which chemical species undergoes reduction? Sn | Sn2+ || NO3- (acid soln), NO(g) | Pt A. Sn B. Sn2+ C. NO3D. NO E. Pt 12. In the following half equation, which is the oxidizing agent? NO3-(aq) + 4H+(aq) + 3e- → NO(g) + 2H2O A. NO3B. H+ C. eD. NO E. H2O 13. Which statement is true for a spontaneous redox reaction carried out at standard-state conditions? A. E°red is always negative. B. E°cell is always positive. C. E°ox is always positive. D. E°red is always positive. 14. Which one of the following reactions will occur spontaneously at standard-state conditions and 25°C? A. Mg2+ + Ca →Mg + Ca2+ B. Au + 3K+ → Au3+ + 3K C. 2Al3+ + 3Fe → 2Al + 3Fe2+ D. Cu + 2H+ → Cu2+ + H 2 15. 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. 16. Consider the following standard reduction potentials in acid solution: The strongest oxidizing agent listed above is A. Cr3+. B. Cr. C. C.Mn2+. D. Co2+. E. 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 reduceMn2+. 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 reduceMn2+. E. H+ can oxidize Fe, and Ni can reduce Br2. 18. Using a table of standard reduction potentials, determine which of these reactions (if any) is/are nonspontaneous in the direction indicated at 25°C. A. 2Fe3+ + 2Cl- → 2Fe2+ + Cl (g) 2 B. 2Fe3+ + 2Br- → 2Fe2+ + Br (l) 2 C. 2Fe3+ + 2I- → 2Fe2+ + I (s) 2 D. 2Fe3+ + 2Cl- → 2Fe2+ + Cl (g) AND 2Fe3+ + 2Br- → 2Fe2+ + Br (l) 2 2 E. All are spontaneous. 19. Which one of the following reagents is capable of transforming Cu2+(1 M) to Cu(s)? A. I- (1 M) B. Ni(s) C. Al3+(1 M) D. F- (1 M) E. Ag(s) 20. 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 21. Determine the equilibrium constant, Keq, at 25°C for the reaction 2Br- (aq) + I2(s) A. 5.7 × 10-19 B. 18.30 C. 1.7 × 1054 D. 1.9 × 1018 E. 5.7 × 10-55 Br2(l) + 2I- (aq) 22. For the electrochemical cell Ni(s) | Ni2+(1 M) || H+(1 M) | H2(1 atm) | Pt(s), which one of the following changes will cause a decrease in the cell voltage? A. Increase the pressure of H2 to 2.0 atm . B. Decrease the mass of the nickel electrode. C. Lower the pH of the cell electrolyte. D. Decrease the concentration of Ni2+ ion. E. none of these 23. Consider an electrochemical cell with the following cell reaction where all reactants and products are at standard-state conditions: Cu2+(aq) + H2(g) → Cu(s) + 2H+(aq). Predict the effect on the emf of this cell of adding NaOH solution to the hydrogen half-cell until the pH equals 7.0. A. The emf will increase. B. The emf will decrease. C. No change in the emf will be observed. 24. Which one of the following reactions must be carried out in an electrolytic cell rather than in an electrochemical cell? A. Zn2+ + Ca → Zn + Ca2+ B. Al3+ + 3Br- → Al + (3/2)Br 2 C. 2Al + 3Fe2+ → 2Al3+ + 3Fe D. H + I (s) → 2H+ + 2I2 2 25. Predict the products obtained from electrolysis of a 1 M AlBr3 solution. Note that A. Al and Br2 B. Al and O2 C. H2 and O2 D. H2 and Br2 E. Al and H2 26. When an aqueous solution of AgNO3 is electrolyzed, a gas is observed to form at the anode. The gas is A. H2. B. O2. C. NO. D. NO2. 27. The half-reaction that occurs at the cathode during electrolysis of an aqueous sodium iodide solution is A. Na+ + e- → Na. B. Na → Na+ + e-. C. 2H O + 2e- → H + 2OH-. 2 2 D. I + 2e- → 2I-. 2 E. 2I- → I + 2e-. 2 28. The half-reaction that occurs at the cathode during electrolysis of an aqueous CuCl2 solution is A. Cu+ + e- → Cu. B. Cu2+ + e- → Cu+. C. 2H O + 2e- → H + 2OH-. 2 2 D. Cl + 2e- → 2Cl-. 2 E. 2Cl- → Cl + 2e-. 2 29. Under standard-state conditions, which of the following half-reactions occurs at the cathode during the electrolysis of aqueous nickel sulfate at 25°C? A. 2H O → O + 4H+ + 4e2 2 B. Ni2+ + 2e- → Ni C. 2H O + 2e- → H + 2OH2 2 D. Ni → Ni2+ + 2e- 30. 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 31. 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 32. How many grams of nickel would be electroplated by passing a constant current of 7.2 A through a solution of NiSO4 for 90.0 min? A. 0.20 g B. 0.40 g C. 12 g D. 24 g E. 47 g 33. How many minutes would be required to electroplate 25.0 grams of chromium by passing a constant current of 4.80 amperes through a solution containing CrCl3? A. 483 min B. 161 min C. 322 min D. 2.01 × 104 min E. 1.11 × 104 min 34. Aluminum does not corrode as does iron, because A. Al does not react with O2. B. a protective layer of Al2O3 forms on the metal surface. C. Al is harder to oxidize than is Fe. D. Fe gives cathodic protection to Al. E. the electrical circuit cannot be completed on an Al surface. 35. Iron objects such as storage tanks and underground pipelines can be protected from corrosion by connecting them through a wire to a piece of A. Pb. B. Ag. C. Sn. D. Mg. E. Cu. 36. Which element is associated with the term "galvanized"? A. Ga B. Zn C. Cd D. Hg E. Pb 37. 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 38. Which of these metals will reduce water to hydrogen in basic solution under standard conditions? A. Pb B. Fe C. Zn D. Na E. Ag Chapter 19 Review Key 1. Complete and balance the following redox equation. When properly balanced using the smallest whole-number coefficients, the coefficient of S is H2S + HNO3 → S + NO (acidic solution) A. B. C. D. E. 1 2 3 5 6 Difficulty: Medium Raymond - 019 Electrochemistry... #1 2. 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. B. C. D. E. 1 2 3 4 5 Difficulty: Medium Raymond - 019 Electrochemistry... #2 3. Complete and balance the following redox equation. What is the coefficient of H2O when the equation is balanced with the set of smallest whole-number coefficients? H2O +MnO4- + I- →MnO2 + IO3- (basic solution) A. B. C. D. E. 1 2 4 10 none of these Difficulty: Medium Raymond - 019 Electrochemistry... #5 4. Complete and balance the following redox equation. Br2 → BrO3- + Br- (basic solution) The sum of the smallest whole-number coefficients is A. 9. B. 12. C. 18. D. 21. E. none of these. Difficulty: Medium Raymond - 019 Electrochemistry... #12 5. 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) → H (g) + 2Ag(s) 2 B. H (g) + 2Ag(s) → H+(aq) + 2Ag+(aq) 2 C. 2H+(aq) + 2Ag(s) → H (g) + 2Ag+(aq) 2 D. H (g) + Ag+(aq) → H+(aq) + Ag(s) 2 E. H (g) + 2Ag+(aq) → 2H+(aq) + 2Ag(s) 2 Difficulty: Medium Raymond - 019 Electrochemistry... #13 6. Consider an electrochemical cell constructed from the following half cells, linked by an external circuit and by a KCl salt bridge. • an Al(s) electrode in 1.0 M Al(NO3)3 solution • a Pb(s) electrode in 1.0 M Pb(NO3)2 solution The balanced overall (net) cell reaction is A. Pb(s) + Al3+(aq) → Pb2+(aq) + Al(s). B. 3Pb(s) + 2Al3+(aq) → 3Pb2+(aq) + 2Al(s). C. 3Pb2+(aq) + 2Al(s) → 3Pb(s) + 2Al3+(aq). D. Pb2+(aq) + Al(s) → Pb(s) + Al3+(aq). Difficulty: Medium Raymond - 019 Electrochemistry... #14 7. 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 Sn electrode in 1.0 M Sn(NO3 )2 solution When the cell is running spontaneously, which choice includes only true statements and no false ones? A. The tin electrode loses mass and the tin electrode is the cathode. B. The tin electrode gains mass and the tin 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. E. The iron electrode gains mass and the iron electrode is the cathode. Difficulty: Medium Raymond - 019 Electrochemistry... #16 8. Calculate the value of E°cell for the following reaction: A. B. C. D. E. 2Au(s) + 3Ca2+(aq) → 2Au3+(aq) + 3Ca(s) -4.37 V -1.37 V -11.6 V 1.37 V 4.37 V Difficulty: Medium Raymond - 019 Electrochemistry... #19 9. Calculate E°cell for a silver-aluminum cell in which the cell reaction is A. B. C. D. E. Al(s) + 3Ag+(aq) → Al3+(aq) + 3Ag(s) -2.46 V 0.86 V -0.86 V 2.46 V none of these Difficulty: Medium Raymond - 019 Electrochemistry... #20 10. Calculate the standard cell emf for the following cell: Mg |Mg2+ || NO3- (acid soln)| NO(g) | Pt A. 3.33 V B. 1.41 V C. -1.41 V D. 8.46 V E. -8.46 V Difficulty: Medium Raymond - 019 Electrochemistry... #24 11. According to the following cell diagram, which chemical species undergoes reduction? Sn | Sn2+ || NO3- (acid soln), NO(g) | Pt A. Sn B. Sn2+ C. NO3D. NO E. Pt Difficulty: Medium Raymond - 019 Electrochemistry... #30 12. In the following half equation, which is the oxidizing agent? NO3-(aq) + 4H+(aq) + 3e- → NO(g) + 2H2O A. B. C. D. E. NO3H+ eNO H2O Difficulty: Medium Raymond - 019 Electrochemistry... #31 13. Which statement is true for a spontaneous redox reaction carried out at standard-state conditions? A. E°red is always negative. B. E°cell is always positive. C. E°ox is always positive. D. E°red is always positive. Difficulty: Easy Raymond - 019 Electrochemistry... #32 14. Which one of the following reactions will occur spontaneously at standard-state conditions and 25°C? A. Mg2+ + Ca →Mg + Ca2+ B. Au + 3K+ → Au3+ + 3K C. 2Al3+ + 3Fe → 2Al + 3Fe2+ D. Cu + 2H+ → Cu2+ + H 2 Difficulty: Medium Raymond - 019 Electrochemistry... #33 15. 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. Difficulty: Medium Raymond - 019 Electrochemistry... #34 16. Consider the following standard reduction potentials in acid solution: The strongest oxidizing agent listed above is A. Cr3+. B. Cr. C. C.Mn2+. D. Co2+. E. E.MnO4-. Difficulty: Medium Raymond - 019 Electrochemistry... #39 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 reduceMn2+. 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 reduceMn2+. E. H+ can oxidize Fe, and Ni can reduce Br2. Difficulty: Medium Raymond - 019 Electrochemistry... #40 18. Using a table of standard reduction potentials, determine which of these reactions (if any) is/are nonspontaneous in the direction indicated at 25°C. A. 2Fe3+ + 2Cl- → 2Fe2+ + Cl (g) 2 B. 2Fe3+ + 2Br- → 2Fe2+ + Br (l) 2 C. 2Fe3+ + 2I- → 2Fe2+ + I (s) 2 D. 2Fe3+ + 2Cl- → 2Fe2+ + Cl (g) AND 2Fe3+ + 2Br- → 2Fe2+ + Br (l) 2 2 E. All are spontaneous. 19. Which one of the following reagents is capable of transforming A. I- (1 M) B. Ni(s) C. Al3+(1 M) D. F- (1 M) E. Ag(s) Cu2+(1 Difficulty: Medium Raymond - 019 Electrochemistry... #41 M) to Cu(s)? Difficulty: Medium Raymond - 019 Electrochemistry... #42 20. 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 Difficulty: Easy Raymond - 019 Electrochemistry... #48 21. Determine the equilibrium constant, Keq, at 25°C for the reaction A. B. C. D. E. 2Br- (aq) + I2(s) 5.7 × 10-19 18.30 1.7 × 1054 1.9 × 1018 5.7 × 10-55 Br2(l) + 2I- (aq) Difficulty: Medium Raymond - 019 Electrochemistry... #49 22. For the electrochemical cell Ni(s) | Ni2+(1 M) || H+(1 M) | H2(1 atm) | Pt(s), which one of the following changes will cause a decrease in the cell voltage? A. Increase the pressure of H2 to 2.0 atm . B. Decrease the mass of the nickel electrode. C. Lower the pH of the cell electrolyte. D. Decrease the concentration of Ni2+ ion. E. none of these Difficulty: Medium Raymond - 019 Electrochemistry... #53 23. Consider an electrochemical cell with the following cell reaction where all reactants and products are at standard-state conditions: Cu2+(aq) + H2(g) → Cu(s) + 2H+(aq). Predict the effect on the emf of this cell of adding NaOH solution to the hydrogen half-cell until the pH equals 7.0. A. The emf will increase. B. The emf will decrease. C. No change in the emf will be observed. Difficulty: Medium Raymond - 019 Electrochemistry... #55 24. Which one of the following reactions must be carried out in an electrolytic cell rather than in an electrochemical cell? A. Zn2+ + Ca → Zn + Ca2+ B. Al3+ + 3Br- → Al + (3/2)Br 2 C. 2Al + 3Fe2+ → 2Al3+ + 3Fe D. H + I (s) → 2H+ + 2I2 2 Difficulty: Medium Raymond - 019 Electrochemistry... #65 25. Predict the products obtained from electrolysis of a 1 M AlBr3 solution. Note that A. B. C. D. E. Al and Br2 Al and O2 H2 and O2 H2 and Br2 Al and H2 Difficulty: Difficult Raymond - 019 Electrochemistry... #66 26. When an aqueous solution of AgNO3 is electrolyzed, a gas is observed to form at the anode. The gas is A. H2. B. O2. C. NO. D. NO2. Difficulty: Difficult Raymond - 019 Electrochemistry... #69 27. The half-reaction that occurs at the cathode during electrolysis of an aqueous sodium iodide solution is A. Na+ + e- → Na. B. Na → Na+ + e-. C. 2H O + 2e- → H + 2OH-. 2 2 D. I + 2e- → 2I-. 2 E. 2I- → I + 2e-. 2 Difficulty: Difficult Raymond - 019 Electrochemistry... #70 28. The half-reaction that occurs at the cathode during electrolysis of an aqueous CuCl2 solution is A. Cu+ + e- → Cu. B. Cu2+ + e- → Cu+. C. 2H O + 2e- → H + 2OH-. 2 2 D. Cl + 2e- → 2Cl-. 2 E. 2Cl- → Cl + 2e-. 2 Difficulty: Difficult Raymond - 019 Electrochemistry... #71 29. Under standard-state conditions, which of the following half-reactions occurs at the cathode during the electrolysis of aqueous nickel sulfate at 25°C? A. 2H O → O + 4H+ + 4e2 2 B. Ni2+ + 2e- → Ni C. 2H O + 2e- → H + 2OH2 2 D. Ni → Ni2+ + 2eDifficulty: Difficult Raymond - 019 Electrochemistry... #73 30. 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 Difficulty: Easy Raymond - 019 Electrochemistry... #75 31. 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 Difficulty: Medium Raymond - 019 Electrochemistry... #78 32. How many grams of nickel would be electroplated by passing a constant current of 7.2 A through a solution of NiSO4 for 90.0 min? A. 0.20 g B. 0.40 g C. 12 g D. 24 g E. 47 g Difficulty: Medium Raymond - 019 Electrochemistry... #81 33. How many minutes would be required to electroplate 25.0 grams of chromium by passing a constant current of 4.80 amperes through a solution containing CrCl3? A. 483 min B. 161 min C. 322 min D. 2.01 × 104 min E. 1.11 × 104 min Difficulty: Medium Raymond - 019 Electrochemistry... #85 34. Aluminum does not corrode as does iron, because A. Al does not react with O2. B. a protective layer of Al2O3 forms on the metal surface. C. Al is harder to oxidize than is Fe. D. Fe gives cathodic protection to Al. E. the electrical circuit cannot be completed on an Al surface. Difficulty: Medium Raymond - 019 Electrochemistry... #87 35. Iron objects such as storage tanks and underground pipelines can be protected from corrosion by connecting them through a wire to a piece of A. Pb. B. Ag. C. Sn. D. Mg. E. Cu. Difficulty: Medium Raymond - 019 Electrochemistry... #88 36. Which element is associated with the term "galvanized"? A. Ga B. Zn C. Cd D. Hg E. Pb Difficulty: Easy Raymond - 019 Electrochemistry... #89 37. 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 Difficulty: Difficult Raymond - 019 Electrochemistry... #94 38. Which of these metals will reduce water to hydrogen in basic solution under standard conditions? A. Pb B. Fe C. Zn D. Na E. Ag Difficulty: Difficult Raymond - 019 Electrochemistry... #96 Chapter 19 Review Summary Category Difficulty: Difficult Difficulty: Easy Difficulty: Medium Raymond - 019 Electrochemistry... # of Questions 7 4 27 38
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