![]() The terms anode and cathode are not defined by the voltage polarity of electrodes but the direction of current through the electrode. Historically, the anode of a galvanic cell was also known as the zincode because it was usually composed of zinc. As a result of this, anions will tend to move towards the anode where they will undergo oxidation. In an electrolytic cell, the anode is the wire or plate upon which excess positive charge is imposed. In a galvanic cell the anode is the wire or plate having excess negative charge as a result of the oxidation reaction. In both a galvanic cell and an electrolytic cell, the anode is the electrode at which the oxidation reaction occurs. For example, the end of a household battery marked with a "-" (minus) is the anode. The direction of conventional current (the flow of positive charges) in a circuit is opposite to the direction of electron flow, so (negatively charged) electrons flow out the anode of a galvanic cell, into an outside or external circuit connected to the cell. A common mnemonic is ACID, for "anode current into device". This contrasts with a cathode, an electrode of the device through which conventional current leaves the device. Note how electrons move out of the cell, and the conventional current moves into it in the opposite direction.Īn anode is an electrode of a polarized electrical device through which conventional current enters the device. Diagram of a zinc anode in a galvanic cell. ![]()
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