19
Electrochemistry III: Electrolysis
Chapter 17 emphasizes the principles associated with obtaining electrical
energy from electron-transfer reactions in solution. This chapter emphasizes
what happens when electrical energy is applied to solutions in the operation of
electrolytic cells. The oxidation and reduction processes that take place in an
electrolytic cell are called electrolysis. We focus on determining what products
are obtained and how much energy is required.
Unlike a galvanic cell, an electrolytic cell needs only a single beaker; both
electrodes are immersed in it. The electrode to which the electrons are furnished by the power supply is the negative electrode; the other electrode is
positive. In solution, the positive ions are attracted to the negative electrode,
and the negative ions to the positive electrode. Thus, conduction of current in
solution is a fe/directional flow of ions, just as in the salt bridge of a galvanic
cell. The electron-transfer process that occurs at each electrode (removal of
electrons from the negative electrode and supply of electrons to the positive
electrode) depends on the material between the electrodes, as we shall see.
THE PRODUCTS OF ELECTROLYSIS
Electrolysis of Molten Salts
The simplest electrolysis processes are those that occur when an electrolytic
cell contains a molten salt, such as NaCl (Figure 19-1). In this situation the Na
+
Electrochemistry III: Electrolysis
Chapter 17 emphasizes the principles associated with obtaining electrical
energy from electron-transfer reactions in solution. This chapter emphasizes
what happens when electrical energy is applied to solutions in the operation of
electrolytic cells. The oxidation and reduction processes that take place in an
electrolytic cell are called electrolysis. We focus on determining what products
are obtained and how much energy is required.
Unlike a galvanic cell, an electrolytic cell needs only a single beaker; both
electrodes are immersed in it. The electrode to which the electrons are furnished by the power supply is the negative electrode; the other electrode is
positive. In solution, the positive ions are attracted to the negative electrode,
and the negative ions to the positive electrode. Thus, conduction of current in
solution is a fe/directional flow of ions, just as in the salt bridge of a galvanic
cell. The electron-transfer process that occurs at each electrode (removal of
electrons from the negative electrode and supply of electrons to the positive
electrode) depends on the material between the electrodes, as we shall see.
THE PRODUCTS OF ELECTROLYSIS
Electrolysis of Molten Salts
The simplest electrolysis processes are those that occur when an electrolytic
cell contains a molten salt, such as NaCl (Figure 19-1). In this situation the Na
+