Anode

An anode (from the Greek ἄνοδος Anodos "Rise ", literally "the way up " ) is an electrode that receives, for example, a vacuum free electrons or discharges from an electrolyte under electron uptake anions or cations generated and thus making oxidation reactions. An anode thus corresponds to an electron or behaves formally as an oxidizing agent.

The anode is the counter electrode to the cathode, which emits electrons and expire at which reducing processes. Anions migrate to the anode and cations to the cathode. The polarity of an anode can be positive or negative when electrochemical processes take place, see below. In previous years, the anode of an X-ray tube was also referred to as anti-cathode.

When electroplating is passed through an electrolytic bath stream. At the positive pole (anode ) is the metal that is to be applied (eg, copper or nickel), the negative ( cathode ) of the object to be coated.

Chemistry

In the chemical industry, in particular the electrochemistry, an anode is the electrode at which oxidation reaction takes place. It will be added electrons from the chemical reaction and output via the electrical connection. An electrochemical reaction always takes place at the phase boundary between an electrode and an electrolyte solution, an ion-conducting solid or melt. Therefore, in electrolysis, the anode is the positive electrode. ( Electrolysis require electrical power. )

In electrochemical elements, which produce electrical energy, the oxidation processes taking place at the anode, i.e. the coming out of the electrolyte anions are discharged or neutral atoms become cations. The anode and cathode then connected to a circuit flowing through these external connecting electrons to the cathode, in the external circuit, the anode then acts as a negative terminal (e.g., for batteries and fuel cells).

Rechargeable batteries ( secondary element, the accumulator ), the same electrode work alternately as an anode or cathode depending on whether the battery is charged or discharged.

So-called sacrificial anodes made ​​of a relatively base metal used as corrosion protection, which they themselves resolved.

Electrical Engineering

In electrical engineering, the anode is an electrode of a cathode ray tube, fluorescent lamp, diode, fuel cell, lead-acid battery and so on. The anode is the electrode to move the electron from the surrounding medium ( electrolyte, vacuum, silicon) to the electrode, and then flow through the external electrical circuit to the cathode. As the reference direction for the current flow in a positive charge carrier refers, and thus the direction of movement of electrons in the opposite direction, so the current in the external circuit from the cathode to the anode passes. Within the component in the current flowing from the anode to the cathode; the circuit is closed.

This statement has nothing to do with whether the potential of the anode is higher or lower than the potential of the cathode; or in other words if the voltage from anode to cathode is positive or negative. There are the terms positive and negative poles; In this case, the potential of the positive pole is always greater than the potential of the negative terminal. Therefore, the voltage from the positive pole to the negative pole always exceeds zero. To give positive pole and negative pole to the stress direction, while the anode and cathode associated with the current direction.

On components, where the anode has a positive voltage relative to the cathode, electric energy into another form of energy (heat, chemical energy, ...) is changed, for example in a tube -emitting diode, a cathode ray tube or an accumulator, which is charged. On components, where the anode has a negative voltage relative to the cathode, electric power is delivered at the expense of another form of energy (e.g., chemical energy ) to the external electric circuit, such as a fuel cell or a storage battery, the discharge will.

Historical

About the Name by Michael Faraday see Faraday laws.