Honors Chemistry
Mr. Urig
Ch 20-21 HW Packet: Oxidation and Reduction
What is a oxidation-reductions reaction?
How are oxidation numbers calculated?
I. Fill in the Blank
1. The oxidation number of an atom of an uncombined, neutral element is ______.
2. The oxidation number of a monatomic ion is ______.
3. Elements in Group 1A of the periodic table have an oxidation number of ______.
4. Elements in group 2A of the periodic table have an oxidation number of ______.
5. In most compounds, aluminum has an oxidation number of ______.
6. Fluorine in compounds has an oxidation number of ______-.
7. When combined with nonmetals, hydrogen’s oxidation number is ______.
8. Oxygen has an oxidation number of ______in most compounds and ions.
9. In a polyatomic ion, the sum of the oxidation numbers is ______.
10. In compounds, the sum of the oxidation numbers is ______.
II. Matching
11. _____ redox reaction
12. _____ reduction
13. _____ oxidizing agent
14. _____ oxidation number A. The substance that accepts electrons from another substance
B. A process in which electrons are transferred between reactants
C. The charge that an atom in a compound would have if the electrons in a bond belonged to the more electronegative atom.
D. The process by which a substance loses one or more electrons.
E. The substance that undergoes oxidation.
F. The process by which a substance gains one or more electrons.
III. Short Answer
15. Can a material be oxidized without another material being reduced? Why or why not?
16. What is the oxidation number of each element in the following compounds?
A. CaCO3
B. P4O6
C. N2O5
17. Which element is oxidized and which element is reduced in the following equations?
A. K2Cr2O7 + 14HI → 2KI + 2CrI3 + 3I2 + 7H2O B. Cu + 2AgNO3 → Cu(NO3)2 + 2Ag
C. Na2SO4 + 4C → Na2S + 4CO
18. Use the activity series to predict if the following reactions will occur. If a reaction does occur, write the complete, balanced equation for the reaction.
A. Zn + HgCl2 →
B. Ag + Pb(NO3)2 →
C. Cu + AgNO3 →
D. Pb + Cu(NO3)2 →
E. Fe + HgCl2 → F. Zn + CaClO4 →
G. Ag + Cu(NO3)2 →
IV. More matching
19. _____ redox of a silver halide
20. _____ corrosion
21. _____bleach
22. _____rust
23. _____explosives
A. The oxidation of a metal caused by a reaction between a metal and a substance in its environment
B. Typically contain both oxidizing and reducing agents
C. Photographic image formation
D. The oxidation product of iron
E. Protests a substance from oxidation
F. Oxidizing agent that removes color
V. Essay
24. List several ways to prevent corrosion and explain why they work VI. Balance the following redox reactions (all in acidic solution)
25. 2+ - 3+ 2+ Fe + MnO4 → Fe + Mn
26. 2- - 2- 2+ SO3 + MnO4 → SO4 + Mn
27. - 2+ Zn + NO3 → Zn + N2O 28. - - - MnO4 + I → MnO2 + IO
29. - - P + NO3 → H2PO4 + NO
30. - - NO3 + I2 → IO3 + NO2
31. - - - - I + ClO → IO3 + Cl 32. 2- - 2- SO3 + MnO4 → SO4 + MnO2
33. - 3+ - 5+ BrO3 + Sb → Br + Sb
34. - 2+ C2H4 + MnO4 → CO2 + Mn
35. 2- - 3+ CrO4 + Cl → Cr + HClO2 36. Cd + AgCl → Cd2+ + Ag + Cl-
37. - - 2+ MnO4 + Cl → Mn + Cl2
VII. True/False – Correct False answers
38. _____ Oxidation involves the gaining of electrons.
39. _____ The transfer of electrons is the basis for electricity.
40. _____ Most metals are poor conductors of electrical current.
41. _____ Voltaic cells use nonspontaneous oxidation-reduction reactions.
42. _____ The electrons in a voltaic cell move from lower energy state to a higher energy state. 43. _____ Electric current is made possible by the movement of positive and negative ion s.
44. _____ A battery is an example of an electrolytic cell.
45. _____ The direct transfer of electrons makes voltaic cells work.
46. _____ The negative electrode of a voltaic cell is the cathode.
47. _____ Electrons move from a higher energy state to a lower energy state.
48. _____ Cell voltage is another term for cell potential.
49. _____ The voltage of any voltaic cell is always positive.
50. _____ The reference electrode for determining potentials is the standard oxygen electrode.
51. _____ A positive reduction potential shows that a metal is easier to reduce than hydrogen.
52. _____ Rechargeable batteries use internal power source to reverse reactions.
53. _____ A common dry-cell uses porous paper as its salt bridge.
54. _____ An alkaline dry cell has a shorter shelf life that a common dry cell.
55. _____ In a lead storage battery, the electrolyte is sulfuric acid.
56. _____ In a nickel-cadmium battery, the anode is composed of cadmium.
57. _____ Most electrolytic cells use inert electrodes.
58. _____ In the electrolysis of water, oxygen forms at the anode.
59. _____ The electrolysis of molten sodium chloride forms chlorine gas.
60. _____ The electrolysis of water is a commercially important source of hydrogen.
61. _____ In electroplating, the plating metal is the cathode of the cell.
VIII. Essays
62. How does an electrolytic cell differ from a voltaic cell. 63. When a car will not start because the battery is “dead” what does that mean chemically?
64. Why is a salt bridge necessary in a voltaic cell?
IX. Calculate Cell Potentials
65. What is the cell potential for a cell with a nickel electrode in contact with a Ni2+ solution and a silver electrode in contact with Ag+ ions? 66. What is the cell potential for a cell with a aluminum electrode in contact with a Al3+ solutions and an iron electrode in contact with Fe3+ ions?
67. What is the cell potential for a cell with a sodium electrode in contact with Na+ ions and a copper electrode in contact with Cu2+ ions?
68. What is the cell potential for a cell with a calcium electrode in contact with Ca2+ ions and a tin electrode in contact with Sn2+ ions?
69. Using the following reactions:
Pb2+ (aq) + 2e- → Pb(s)
Au3+ (aq) + 3e- → Au(s)
A. Which is the anode? Cathode?
B. What is the cell potential? 70. What is the cell potential for a cell with a nickel electrode in contact with Ni2+ and a copper electrode in contact with Cu2+ ions?
71. Using the following reactions:
Mn2+ (aq) + 2e- → Mn(s)
Cu2+ (aq) + 2e- → Cu(s)
A. Which is the anode? Cathode?
B. What is the cell potential?
72. What is the voltage produced by a voltaic cell consisting of a lead electrode in contact with a solution of Pb2+ ions and an iron electrode in contact with a solution of Fe2+ ions? Which is the anode and which is the cathode? 73. What is the voltage produced by a voltaic cell consisting of a zinc electrode in contact with a solution of Zn2+ ions and a silver electrode in contact with a solution of Ag+ ions?
74. Calculate the standard potential produced by a voltaic cell consisting of a gold electrode in contact with a solution of Au3+ ions and a silver electrode in contact with a solution of Ag+ ions. Which is the anode and which is the cathode?