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212 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 20
iron can be prevented by galvanizing, or coating the iron with a
layer of zinc. Zinc is a self-protecting metal that oxidizes only at the
surface, so the zinc coating protects the iron underneath.
20.3 Electrolysis
The use of electrical energy to bring about a nonspontaneous redox
reaction is called electrolysis. For example, the electrolysis of water
uses an electric current to decompose water into hydrogen and oxygen.
electric current
2H 2 O(l) ---------0 2H 2 (g) ϩ O 2 (g)
Electrolysis takes place in an electrolytic cell. Two of the most useful applications of electrolysis are the separation of molten sodium
chloride into sodium metal and chlorine gas, and the decomposition
of brine (NaCl solution) to form hydrogen gas, chlorine gas, and
sodium hydroxide. Electrolysis is also used to produce aluminum
metal from aluminum oxide in the Hall–Héroult process.
Chapter 20 Review
8. The following metals can be oxidized to form ions with a 2ϩ
charge: Zn, Mg, Pt, Ca, Pb. Use Table 20-1 in your textbook to
rank these metals from the most easily oxidized to the least easily oxidized.
9. Answer the following questions about this voltaic cell.
CdΈCd 2ϩ ΈΈSn 2ϩ ΈSn
a. Which electrode is the anode?
b. Which electrode gains mass during the reaction?
c. What is the reducing agent?
d. What is the overall cell reaction?
e. What is the standard cell potential?
10. The standard potential of a voltaic cell is ϩ2.197 V, and the
reduction half-reaction is I 2 (s) ϩ 2e Ϫ 0 2I Ϫ (aq). Use Table
20-1 in your textbook to determine the probable oxidation halfreaction for this cell.
11. Name three ways to protect iron from corrosion.
12. Distinguish between a voltaic cell and an electrolytic cell.
212 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 20
iron can be prevented by galvanizing, or coating the iron with a
layer of zinc. Zinc is a self-protecting metal that oxidizes only at the
surface, so the zinc coating protects the iron underneath.
20.3 Electrolysis
The use of electrical energy to bring about a nonspontaneous redox
reaction is called electrolysis. For example, the electrolysis of water
uses an electric current to decompose water into hydrogen and oxygen.
electric current
2H 2 O(l) ---------0 2H 2 (g) ϩ O 2 (g)
Electrolysis takes place in an electrolytic cell. Two of the most useful applications of electrolysis are the separation of molten sodium
chloride into sodium metal and chlorine gas, and the decomposition
of brine (NaCl solution) to form hydrogen gas, chlorine gas, and
sodium hydroxide. Electrolysis is also used to produce aluminum
metal from aluminum oxide in the Hall–Héroult process.
Chapter 20 Review
8. The following metals can be oxidized to form ions with a 2ϩ
charge: Zn, Mg, Pt, Ca, Pb. Use Table 20-1 in your textbook to
rank these metals from the most easily oxidized to the least easily oxidized.
9. Answer the following questions about this voltaic cell.
CdΈCd 2ϩ ΈΈSn 2ϩ ΈSn
a. Which electrode is the anode?
b. Which electrode gains mass during the reaction?
c. What is the reducing agent?
d. What is the overall cell reaction?
e. What is the standard cell potential?
10. The standard potential of a voltaic cell is ϩ2.197 V, and the
reduction half-reaction is I 2 (s) ϩ 2e Ϫ 0 2I Ϫ (aq). Use Table
20-1 in your textbook to determine the probable oxidation halfreaction for this cell.
11. Name three ways to protect iron from corrosion.
12. Distinguish between a voltaic cell and an electrolytic cell.