23.3. Electrolysis http://www.ck12.org
FIGURE 23.10
An electrolytic cell used in the electroplating of silver onto a metal spoon.
A silver strip is the anode, while the spoon itself is the cathode.Meanwhile, silver ions from the solution are reduced to silver metal on the surface of the cathode, the steel spoon.
Cathode: Ag+(aq)+e−→Ag(s)The concentration of silver ions in the solution is effectively constant. The electroplating process transfers metal
from the anode to the cathode of the cell. Other metals commonly plated onto objects include chromium, gold,
copper, and platinum.
Lesson Summary
- Electrolysis is a process in which a nonspontaneous redox reaction is driven forward by an external power
source, such as a battery. The voltage of the battery must be at least as great as the negative cell potential. - Molten sodium chloride can be electrolyzed in a Down’s cell to yield sodium metal and chlorine gas.
- The electrolysis of water produces hydrogen and oxygen gases.
- When a concentrated aqueous solution of sodium chloride (brine) is electrolyzed, chlorine and hydrogen gases
are produced. - Electroplating is a process by which a solution of metal ions is plated out as a neutral metal surface onto the
object used as the cathode.
Lesson Review Questions
Reviewing Concepts
- Distinguish between a voltaic cell and an electrolytic cell, in terms of the nature of the redox reaction.