Electrochemistry is a science that deals with chemical reactions that involve electricity. Most electrochemical reactions take place in a vessel that has two electrodes surrounded by an electrolyte. Electrodes are usually solid metal. They enable electricity to enter or leave the electrolyte. An electrolyte is a substance that conducts electricity. Electrolytes often contain charged particles called ions. Electrochemical processes are used to produce chemicals and electricity, to refinish and plate metals, and to conduct research.
Some electrochemical processes produce electricity from chemical changes, and others use electricity to produce chemical changes. A series of reactions among the chemicals in a battery, for example, produce an electric current (see Battery). A similar process occurs in fuel cells, devices that typically use hydrogen and oxygen to produce electric power (see Fuel cell). In a process called electrolysis, an electric current passing through a chemical solution separates certain elements from the solution. For example, manufacturers make chlorine by passing electricity through salt water. Electrolysis is also used to separate aluminum, magnesium, and certain other metals from molten salts. Some metals are plated by means of electrolysis (see Electrolysis; Electroplating).
The corrosion of metals in the presence of moisture is a naturally occurring electrolytic process. Electrochemists study corrosion to develop ways to protect metals. Electrochemical studies also include the electroanalysis of solutions and other chemical systems. In electroanalysis, the composition of such systems is studied by observing their response to electrical signals.
Electrochemistry includes several special fields. Scientists in the field of photoelectrochemistry seek ways of using light energy to produce electricity or chemical changes. Bioelectrochemistry deals with electrochemical processes that occur in the body. Such electrochemical processes include the production of brain waves and nerve impulses.
