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210 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 20
Practice Problems
3. Calculate the cell potential to determine if each of these redox
reactions is spontaneous. The half-reactions can be found in
Table 21-1 in your textbook.
a. 2Ag ϩ (aq) ϩ Co(s) 0 Co 2ϩ (aq) ϩ 2Ag(s)
b. Cu(s) ϩ Cu 2ϩ (aq) 0 2Cu ϩ (aq)
c. 2Br 2 (l) ϩ 2H 2 O(l) 0 4H ϩ (aq) ϩ 4Br Ϫ (aq) ϩ O 2 (g)
d. 5Fe 2ϩ (aq) ϩ MnO 4
Ϫ (aq) ϩ 8H ϩ (aq) 0
5Fe 3ϩ (aq) ϩ Mn 2ϩ (aq) ϩ 4H 2 O(l)
20.2 Types of Batteries
A battery is one or more voltaic cells in a single package that generates an electric current. There are several types of batteries with
various applications.
Dry cells You are probably most familiar with the type of battery
knows as the dry cell, which contains a moist paste in which the
cathode half-reaction occurs. Three types of dry cells are the
zinc–carbon dry cell, the alkaline cell, and the mercury cell. Zinc is
oxidized in each of these dry cells. In the zinc–carbon dry cell, the
zinc shell is the anode and a carbon rod is the cathode. The newer
alkaline batteries are smaller than zinc–carbon dry cells. Mercury
batteries are even smaller and are used in such devices as hearing
aids and calculators.
Zinc–carbon, alkaline, and mercury cells are primary batteries,
which are not rechargeable. Batteries that are rechargeable are called
secondary batteries, or storage batteries. A storage battery produces
energy from a reversible redox reaction, which occurs in the opposite direction when the battery is recharged. A nickel–cadmium
rechargeable battery is an example of a secondary battery.
Lead–acid storage batteries The standard automobile battery is
a secondary battery called a lead–acid battery. Lead is both oxidized
and reduced in a lead–acid battery. A sulfuric acid solution acts as
the electrolyte, so ions can migrate between electrodes. The sulfuric
acid is used up as the battery generates electric current, but it is
restored as the battery is recharged.
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210 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 20
Practice Problems
3. Calculate the cell potential to determine if each of these redox
reactions is spontaneous. The half-reactions can be found in
Table 21-1 in your textbook.
a. 2Ag ϩ (aq) ϩ Co(s) 0 Co 2ϩ (aq) ϩ 2Ag(s)
b. Cu(s) ϩ Cu 2ϩ (aq) 0 2Cu ϩ (aq)
c. 2Br 2 (l) ϩ 2H 2 O(l) 0 4H ϩ (aq) ϩ 4Br Ϫ (aq) ϩ O 2 (g)
d. 5Fe 2ϩ (aq) ϩ MnO 4
Ϫ (aq) ϩ 8H ϩ (aq) 0
5Fe 3ϩ (aq) ϩ Mn 2ϩ (aq) ϩ 4H 2 O(l)
20.2 Types of Batteries
A battery is one or more voltaic cells in a single package that generates an electric current. There are several types of batteries with
various applications.
Dry cells You are probably most familiar with the type of battery
knows as the dry cell, which contains a moist paste in which the
cathode half-reaction occurs. Three types of dry cells are the
zinc–carbon dry cell, the alkaline cell, and the mercury cell. Zinc is
oxidized in each of these dry cells. In the zinc–carbon dry cell, the
zinc shell is the anode and a carbon rod is the cathode. The newer
alkaline batteries are smaller than zinc–carbon dry cells. Mercury
batteries are even smaller and are used in such devices as hearing
aids and calculators.
Zinc–carbon, alkaline, and mercury cells are primary batteries,
which are not rechargeable. Batteries that are rechargeable are called
secondary batteries, or storage batteries. A storage battery produces
energy from a reversible redox reaction, which occurs in the opposite direction when the battery is recharged. A nickel–cadmium
rechargeable battery is an example of a secondary battery.
Lead–acid storage batteries The standard automobile battery is
a secondary battery called a lead–acid battery. Lead is both oxidized
and reduced in a lead–acid battery. A sulfuric acid solution acts as
the electrolyte, so ions can migrate between electrodes. The sulfuric
acid is used up as the battery generates electric current, but it is
restored as the battery is recharged.
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▲