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American Chemical Society General Chemistry Nuclear and Electrochemistry

Galvanic cells, standard potentials, electrolysis, and nuclear equations.

These questions are original. This is not an official American Chemical Society exam, and FreeExam is not affiliated with the American Chemical Society.

  1. 1.A galvanic cell pairs Zn2+(aq) + 2e− → Zn(s), E° = −0.76 V, with Cu2+(aq) + 2e− → Cu(s), E° = +0.34 V. Which metal is the anode?

  2. 2.Magnesium and silver half-cells are connected. Mg2+(aq) + 2e− → Mg(s) is −2.37 V, and Ag+(aq) + e− → Ag(s) is +0.80 V. Which half-reaction runs at the cathode?

  3. 3.Iron and silver electrodes stand in their ion solutions. Fe2+(aq) + 2e− → Fe(s) is −0.44 V, and Ag+(aq) + e− → Ag(s) is +0.80 V. Where does oxidation take place?

  4. 4.Nickel and copper half-reactions are Ni2+(aq) + 2e− → Ni(s), E° = −0.25 V, and Cu2+(aq) + 2e− → Cu(s), E° = +0.34 V. Which electrode assignment is correct?

  5. 5.Both couples in a cell are negative: Cd2+(aq) + 2e− → Cd(s), E° = −0.40 V, and Pb2+(aq) + 2e− → Pb(s), E° = −0.13 V. Which metal is the cathode?

  6. 6.Aluminum and tin form a galvanic cell. Al3+(aq) + 3e− → Al(s) is −1.66 V, and Sn2+(aq) + 2e− → Sn(s) is −0.14 V. Electrons in the wire leave which electrode?

  7. 7.A cell uses Mg2+(aq) + 2e− → Mg(s), E° = −2.37 V, and Zn2+(aq) + 2e− → Zn(s), E° = −0.76 V. Which species is reduced?

  8. 8.A zinc strip and a hydrogen electrode share a circuit. Zn2+(aq) + 2e− → Zn(s) is −0.76 V, and 2H+(aq) + 2e− → H2(g) is 0.00 V. Which electrode is the site of reduction?

  9. 9.Chromium and nickel half-cells are Cr3+(aq) + 3e− → Cr(s), E° = −0.74 V, and Ni2+(aq) + 2e− → Ni(s), E° = −0.25 V. Which label for the anode is right?

  10. 10.Find E°cell for Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s). The standard reduction potentials are −0.76 V for Zn2+/Zn and +0.34 V for Cu2+/Cu.

  11. 11.Calculate E°cell for Cu(s) + 2Ag+(aq) → Cu2+(aq) + 2Ag(s). E° is +0.34 V for Cu2+/Cu and +0.80 V for Ag+/Ag. Do not multiply the potential by two.

  12. 12.The reaction is written Cu(s) + Zn2+(aq) → Cu2+(aq) + Zn(s). E°(Zn2+/Zn) = −0.76 V and E°(Cu2+/Cu) = +0.34 V. What is E°cell?

  13. 13.Magnesium metal is placed in acid: Mg(s) + 2H+(aq) → Mg2+(aq) + H2(g). E° is −2.37 V for Mg2+/Mg and 0.00 V for H+/H2. Compute E°cell.

  14. 14.For 2Al(s) + 3Fe2+(aq) → 2Al3+(aq) + 3Fe(s), E°(Al3+/Al) = −1.66 V and E°(Fe2+/Fe) = −0.44 V. What is E°cell?

  15. 15.Cadmium metal meets nickel ion: Cd(s) + Ni2+(aq) → Cd2+(aq) + Ni(s). E°(Ni2+/Ni) = −0.25 V and E°(Cd2+/Cd) = −0.40 V. Find E°cell.

  16. 16.Silver metal is mixed with copper(II) ion: 2Ag(s) + Cu2+(aq) → 2Ag+(aq) + Cu(s). E° is +0.80 V for Ag+/Ag and +0.34 V for Cu2+/Cu. What is E°cell?

  17. 17.Zinc is combined with chromium(III): 3Zn(s) + 2Cr3+(aq) → 3Zn2+(aq) + 2Cr(s). E°(Cr3+/Cr) = −0.74 V and E°(Zn2+/Zn) = −0.76 V. Compute E°cell.

  18. 18.The equation is written Fe2+(aq) + Co(s) → Fe(s) + Co2+(aq). E°(Fe2+/Fe) = −0.44 V and E°(Co2+/Co) = −0.28 V. What is E°cell?

  19. 19.In the galvanic cell based on zinc at −0.76 V and copper at +0.34 V, the spontaneous direction is Zn + Cu2+ → Zn2+ + Cu. Which metal dissolves, and which plates out?

  20. 20.A magnesium bar and a silver bar dip into Mg2+ and Ag+ solutions. E°(Mg2+/Mg) = −2.37 V and E°(Ag+/Ag) = +0.80 V. What happens to each metal in the spontaneous cell?

  21. 21.Aluminum metal shares a galvanic cell with a copper electrode. Al3+/Al is −1.66 V and Cu2+/Cu is +0.34 V. Which change occurs at the two electrodes?

  22. 22.Cadmium and lead have reduction potentials of −0.40 V and −0.13 V. The cell runs in the spontaneous direction. Which metal dissolves, and which plates out?

  23. 23.Tin is paired with copper. E°(Sn2+/Sn) = −0.14 V and E°(Cu2+/Cu) = +0.34 V, and the cell runs spontaneously. What happens to the tin electrode?

  24. 24.Nickel and silver half-cells operate spontaneously. Ni2+/Ni is −0.25 V and Ag+/Ag is +0.80 V. Which description of the two metals is correct?

  25. 25.Manganese and zinc are the two electrodes. E°(Mn2+/Mn) = −1.18 V and E°(Zn2+/Zn) = −0.76 V. In the spontaneous cell, what do the metals do?

  26. 26.A chromium rod and an iron rod are the electrodes. Cr3+/Cr is −0.74 V and Fe2+/Fe is −0.44 V. Which rod gets smaller, and which gains metal?

  27. 27.Cobalt metal can react with lead(II) ion. E°(Co2+/Co) = −0.28 V and E°(Pb2+/Pb) = −0.13 V. Which metal dissolves, and which plates out?

  28. 28.A Zn-Cu galvanic cell uses a KNO3 salt bridge. Zinc is the anode (E° = −0.76 V) and copper is the cathode (E° = +0.34 V). Which way do nitrate ions move?

  29. 29.Magnesium is the anode and silver is the cathode, with E° values −2.37 V and +0.80 V. A NaCl salt bridge joins the half-cells. Where do the chloride ions go?

  30. 30.In an Al-Ni galvanic cell, aluminum is the anode and nickel is the cathode. E° values are −1.66 V and −0.25 V. The bridge is K2SO4. Where do sulfate ions move?

  31. 31.Iron is oxidized and copper(II) is reduced. E°(Fe2+/Fe) = −0.44 V and E°(Cu2+/Cu) = +0.34 V. In which direction do the salt-bridge anions move?

  32. 32.Cadmium is the anode at −0.40 V and lead is the cathode at −0.13 V. Why do anions from the salt bridge move as they do?

  33. 33.Tin is the anode (−0.14 V) and silver is the cathode (+0.80 V). A KNO3 bridge joins the half-cells. Which ion movement is correct?

  34. 34.A Zn-Pb galvanic cell has zinc as the anode (−0.76 V) and lead as the cathode (−0.13 V). The bridge contains KCl. Where does Cl− go?

  35. 35.As a Ni-Cu cell runs, Ni2+ forms at the nickel anode. E°(Ni2+/Ni) = −0.25 V and E°(Cu2+/Cu) = +0.34 V. What does the salt bridge send toward that anode?

  36. 36.Chromium is the anode and iron is the cathode. E°(Cr3+/Cr) = −0.74 V and E°(Fe2+/Fe) = −0.44 V. A sodium nitrate bridge is used. Where do nitrate ions migrate?

  37. 37.Zinc is oxidized and Cu2+ is reduced. E° values are −0.76 V and +0.34 V. Which cell notation puts the anode on the left?

  38. 38.Magnesium metal is the anode and silver ion is reduced. E°(Mg2+/Mg) = −2.37 V and E°(Ag+/Ag) = +0.80 V. Choose the correct line notation.

  39. 39.Iron has E° = −0.44 V and nickel has E° = −0.25 V. The spontaneous cell oxidizes iron. Which notation is correct?

  40. 40.Aluminum is oxidized and copper(II) is reduced. E°(Al3+/Al) = −1.66 V and E°(Cu2+/Cu) = +0.34 V. Which shorthand has the anode on the left?

  41. 41.A galvanic cell is written Cd(s) | Cd2+(aq) || Pb2+(aq) | Pb(s). E°(Cd2+/Cd) = −0.40 V and E°(Pb2+/Pb) = −0.13 V. Which electrode is the anode?

  42. 42.The notation Sn(s) | Sn2+(aq) || Ag+(aq) | Ag(s) matches E°(Sn2+/Sn) = −0.14 V and E°(Ag+/Ag) = +0.80 V. What does the left-hand side represent?

  43. 43.Zinc is the anode and H+ is reduced on platinum. E°(Zn2+/Zn) = −0.76 V and E°(H+/H2) = 0.00 V. Which notation is correct?

  44. 44.Cobalt metal dissolves and copper plates out. E°(Co2+/Co) = −0.28 V and E°(Cu2+/Cu) = +0.34 V. Select the cell notation.

  45. 45.Manganese has E° = −1.18 V and zinc has E° = −0.76 V. The spontaneous cell oxidizes manganese. Which notation follows that fact?

  46. 46.Molten sodium chloride is electrolyzed. E°(Na+/Na) = −2.71 V and E°(Cl2/Cl−) = +1.36 V, so making sodium and chlorine has E°cell = −4.07 V. Where does oxidation occur?

  47. 47.Molten magnesium chloride is electrolyzed to make magnesium and chlorine. E°(Mg2+/Mg) = −2.37 V and E°(Cl2/Cl−) = +1.36 V. Which statement is correct?

  48. 48.A power supply reverses Zn + Cl2 → Zn2+ + 2Cl−. From E°(Zn2+/Zn) = −0.76 V and E°(Cl2/Cl−) = +1.36 V, that forward E°cell is +2.12 V. What does the electrolysis do?

  49. 49.During electrolysis of molten sodium bromide, bromide is oxidized and sodium ion is reduced. E°(Na+/Na) = −2.71 V and E°(Br2/Br−) = +1.07 V. The anode is attached to which terminal?

  50. 50.A student wants Cu(s) + Zn2+(aq) → Cu2+(aq) + Zn(s). E°(Cu2+/Cu) = +0.34 V and E°(Zn2+/Zn) = −0.76 V. What does that reaction require?

  51. 51.Molten calcium chloride is electrolyzed. E°(Ca2+/Ca) = −2.87 V and E°(Cl2/Cl−) = +1.36 V. Where is chloride oxidized?

  52. 52.Electrolysis of water reverses the fuel-cell reaction 2H2 + O2 → 2H2O, whose E°cell is +1.23 V. During the electrolysis, where is O2 produced?

  53. 53.Molten potassium fluoride is electrolyzed. E°(K+/K) = −2.92 V and E°(F2/F−) = +2.87 V. What happens to fluoride?

  54. 54.A steel spoon and a nickel strip sit in Ni2+ solution on a power source. E°(Ni2+/Ni) = −0.25 V. Where does nickel metal plate?

  55. 55.A silver plating bath uses Ag+ + e− → Ag, so one mole of electrons makes one mole of silver. If 0.40 mol of electrons is supplied, how many moles of Ag form?

  56. 56.Scrap copper is recovered by Cu2+ + 2e− → Cu. Two moles of electrons deposit one mole of copper. A run supplies 0.50 mol of electrons. How much Cu metal forms?

  57. 57.An aluminum cell reduces Al3+ with three moles of electrons per mole of Al. How many moles of aluminum form when 0.90 mol of electrons is used?

  58. 58.A magnesium plant runs Mg2+ + 2e− → Mg. Two moles of electrons are required for each mole of Mg. How many moles of electrons make 0.20 mol of magnesium?

  59. 59.Molten-salt electrolysis reduces Na+ to sodium. One mole of electrons produces one mole of Na. If 1.50 mol of electrons passes, how many moles of sodium form?

  60. 60.A bolt is zinc plated from Zn2+. Two moles of electrons deposit one mole of zinc. After 1.20 mol of electrons has passed, how many moles of Zn have plated?

  61. 61.A contact is gold plated by Au3+ + 3e− → Au. Three moles of electrons make one mole of gold. How many moles of electrons deposit 0.15 mol of Au?

  62. 62.Lead is collected by Pb2+ + 2e− → Pb. Two moles of electrons produce one mole of lead. How many moles of Pb form from 0.80 mol of electrons?

  63. 63.Decorative chromium is deposited from Cr3+. Three moles of electrons are used for each mole of Cr. How many moles of electrons deposit 0.60 mol of chromium?

  64. 64.Radium-226 emits an alpha particle, 4/2 He. Which nucleus completes 226/88 Ra → ? + 4/2 He?

  65. 65.Carbon-14 emits a beta particle, 0/−1 e. Which nucleus balances 14/6 C → ? + 0/−1 e?

  66. 66.Uranium-238 undergoes alpha emission. Which equation is balanced in both mass number and atomic number?

  67. 67.Phosphorus-32 is a beta emitter. What nucleus completes 32/15 P → ? + 0/−1 e?

  68. 68.Polonium-210 emits an alpha particle. Identify the missing nucleus in 210/84 Po → ? + 4/2 He.

  69. 69.Strontium-90 decays by beta emission. Which product balances 90/38 Sr → ? + 0/−1 e?

  70. 70.Americium-241 emits an alpha particle. Complete 241/95 Am → ? + 4/2 He.

  71. 71.Iodine-131 emits a beta particle. Which nucleus balances 131/53 I → ? + 0/−1 e?

  72. 72.Radon-222 emits an alpha particle. Choose the balanced daughter for 222/86 Rn → ? + 4/2 He.

  73. 73.One emission drops a nucleus’s mass number by 4 and its atomic number by 2. Which emission is that?

  74. 74.After one emission, a nucleus keeps the same mass number, but its atomic number is 1 higher. Which particle left?

  75. 75.An excited nucleus emits gamma radiation and is still the same nuclide. What changed in that emission?

  76. 76.Which emission changes the atomic number and leaves the mass number the same?

  77. 77.A sample can emit alpha, beta, or gamma radiation. Which comparison of the three is correct?

  78. 78.Technetium-99m, 99/43 Tc in an excited nuclear state, emits one gamma photon. What are the mass number and atomic number afterward?

  79. 79.Which single emission changes both the mass number and the atomic number?

  80. 80.A classmate says a nucleus loses protons by emitting gamma radiation. For a gamma photon, what is accurate?

  81. 81.Sort alpha, beta, and gamma by what each changes. Which sorting is right?

  82. 82.Iodine-131 has a half-life of 8.0 days. An 80 mg sample is stored for 16 days. How much of the isotope remains?

  83. 83.A stored isotope is assigned a half-life of 5.0 years. Starting from 64 g, what mass remains after 15 years?

  84. 84.Technetium-99m has a half-life of 6.0 hours. A 120 mg dose is prepared at noon. How much of that isotope remains at 6 p.m.?

  85. 85.An isotope used in a timing exercise has a half-life of 4.0 days. A vial starts at 160 mg. How much remains after 16 days?

  86. 86.A pure radioisotope sample passes through exactly two half-lives. What fraction of the original nuclei has decayed?

  87. 87.A sample has fallen to 1/16 of its starting amount, and only whole half-lives have passed. How many half-lives is that?

  88. 88.A 64 mg specimen has gone through 5 half-lives. What mass of the isotope remains?

  89. 89.A tracer has a half-life of 3.0 hours. Its amount drops from 40 mg to 5 mg. How much time passed?

  90. 90.A classroom decay model uses a half-life of 2.0 days. What fraction of the isotope remains after 8.0 days?

  91. 91.In one step of the uranium series, 234/92 U emits an alpha particle. Which daughter is produced?

  92. 92.The series continues when 234/90 Th emits a beta particle. What is the daughter of that single step?

  93. 93.Later in a decay series, 214/84 Po emits an alpha particle. Identify the daughter of that step.

  94. 94.214/82 Pb decays by beta emission in the same series. Which nucleus is the daughter?

  95. 95.210/82 Pb undergoes one beta decay in the series. What is the parent-to-daughter result?

  96. 96.One series step produces 234/92 U by beta emission. Which parent gives that daughter in a single beta step?

  97. 97.230/90 Th emits an alpha particle as its series step. Which daughter forms?

  98. 98.218/84 Po decays by alpha emission. What is the daughter nucleus for this one step?

  99. 99.210/83 Bi emits a beta particle. Which daughter closes this series step?

  100. 100.Which nuclear process is fission?

  101. 101.Which nuclear process is fusion?

  102. 102.Uranium-235 can split into two mid-mass nuclei after it takes in a neutron. Why can that fission release energy?

  103. 103.Deuterium and tritium can combine to form helium. Why can that fusion release energy?

  104. 104.On a plot of binding energy per nucleon against mass number, where is the curve highest?

  105. 105.Which change is fusion, rather than fission or a single radioactive decay?

  106. 106.Which change is fission?

  107. 107.For the right nuclei, both fission and fusion can release energy. Which statement matches that fact?

  108. 108.Iron sits near the top of the binding-energy curve. Would fusing two iron nuclei release energy the way hydrogen fusion does?