Explain galvanic cells .
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A galvanic cell is an electrochemical cell that uses the transfer of electrons in redox reactions to supply an electric current. This cell is driven by a spontaneous chemical reaction that produces an electric current through an outside circuit. Galvanic cell reactions supply energy, which is used to perform work. For this reason, galvanic cells are commonly used as batteries. In the real world, the word battery has come to include a single galvanic cell, but a proper battery consists of multiple cells.
A galvanic cell consists of at least two half cells, a reduction cell and an oxidation cell. Chemical reactions in the two half cells provide the energy for the galvanic cell operations. Many galvanic cells are of commercial importance. These include dry cells, mercury cells, rechargeable Ni-Cd batteries, fuel cells and lead storage cells. A common galvanic cell is the Daniell cell.
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A galvanic cell is a device in which a spontaneous oxidation-reduction reaction is used to convert chemical energy into electrical energy. Galvanic cells harness the electrical energy available from the electron transfer in a redox reaction to perform useful electrical work. Basically, a galvanic cell is used to convert the chemical energy stored in the ions into electrical energy, in the form of current. For example, a battery is a package of one or more galvanic cells used for the production and storage of electric energy by chemical means.
The key to gathering the electron flow is to separate the oxidation and reduction half-reactions, connecting them by a wire, so that the electrons must flow through that wire. That electron flow, called a current, can be sent through a circuit which could be part of any number of electrical devices such as radios, televisions, watches, etc.
Galvanic cells are also important for corrosion protection. Any two metals can be used to make a galvanic cell. If two metals are in contact, one metal can be the anode and the other the cathode, leading to galvanic corrosion of the more anodic metal. Two metals having different potentials in a conducting electrolyte result in the more anodic metal usually being attacked by galvanic corrosion. Whether a metal will behave as an anode or a cathode in combination with another metal in the same environment can usually be determined by its relative position on the galvanic series. The metal which appears higher up on the list will, in general, be the anode and will thus corrode. The metal lower down on the list will be the cathode and thus will not corrode. Of course, this galvanic action will not take place under open-circuit conditions; there must be a connecting circuit.
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