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Chemistry of a Battery

Skills to develop

Chemistry of a Battery

A battery is a package of one or more galvanic cells used for the production and storage of electric energy by chemical means. A battery consists of at least two half cells or two galvanic cells, a reduction cell and an oxidation cell. Chemical reactions are involved in the cells, and an introduction to the Chemistry of a Battery leads you to understand the magics of a switch in a battery operated device.

A galvanic cell consists of an electrode and an electrolyte solution. Usually the solution contains ions derived from the electrode by oxidation or reduction reaction.

We will make this introduction using a typical setup as depicted here.

Oxidation Reduction Reactions

Many difinitions can be given to oxidation and reduction reactions. In terms of battery chemistry

Loss of electrons is oxidation, and gain of electrons is reduction.

A reducing agent and an oxidizing agent may form a redox couple as defined by

oxidizing agent + n e- = reducing agent

Theoretically, any redox couple may be used as battery material, but we have considerable technical difficulty in making some couples react in the form of battery.

The DEMONSTRATION (valid in DOS CACT only) in this module illustrates the chemical process in a battery. It simulates the chemical reactions in a galvanic cell:

Zn | Zn2+ || Cu2+ | Cu.

When the Zn electrode dissolves in the form of Zn2+ions, the electron leaves the electrode, passes the load (wire), and reaches the Cu electrode. At this point, the electrons disappear, and Cu2+ ions are neutralized to become Cu metal which then deposits on the Cu electrode. (Would someone write me a JAVA script to simulate the above. It will take me some time before I get around to do it.)

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