Chemical Action Produced from Electricity
Probably the most common example of chemical action produced from electricity is the recharging of the ordinary automobile storage battery. When the cells of the storage battery are being used to generate electricity, a chemical reaction takes place. If a current is sent through the cells in the opposite direction, the reaction runs in the other direction and the battery is recharged. Cells that do this are called secondary cells. Most secondary cells used in storage batteries are of the lead-acid type. In this cell, the electrolyte is sulfuric acid, the positive plate is lead peroxide, and the negative plate is lead. During discharge of the cell, the acid becomes weaker and both plates change chemically to lead sulfate. Recharging reconverts the lead sulfate to pure lead on one plate and lead peroxide on the other, and the strength of the sulfuric acid electrolyte increases. Other types of secondary cells use nickel and iron, nickel and cadmium, or silver and zinc in a potassium hydroxide electrolyte.
Since the basic force that holds compounds together is electrical in nature, it is not surprising that chemical compounds can be broken down by electricity. This process is called electrolysis, or electrolytic action, and is very important in the manufacture of many metals (aluminum, copper, etc.) and other substances. An additional important use of chemical action produced from electricity is in electroplating. Here, metal ions are made to migrate to an electrode and adhere to it when they are changed from ions to the metal. Although we will not look into the chemical action produced by electricity any further in our present studies, it is nonetheless a very important part of our industrial and personal life.