Cathode and Anode

In electrochemical cells, semiconductor diodes and in some medical devices, electrodes are used as a conductor which conducts electricity from non-metallic parts of the circuits. In other words, we can say that an electrode is a substance which conducts electricity in the electric current, which either enters or leaves the non-metallic medium like an electrolyte. Anode and cathode are the two types of electrodes. An anode is an electrode from which polarized current enters the outer circuit, and a cathode is an electrode from which a conventional current leaves a polarized electrical device. The anode and cathode charge are positive and negative respectively. The anode cathode symbol respectively are A and K.

The word anode originates from the Greek word anodes which means way up, and the word cathode originates from another Greek word, cathodes which means way down.

Electrochemical Cell

What is Anode and Cathode?

Anode and cathode are electrodes used in an electrolytic cell and electrochemical cell. Anode and cathode sign are positive and negative. A and K are the respective symbols of anode and cathode. The details of anode and cathode are given below.

• Anode

Generally, the anode is the electrode where oxidation reaction takes place, which means at the anode, electrons are getting released into the external circuit. In the electrolytic cell, the anode is a positive electrode, and in the galvanic cell, the anode is a negative one. the sign of anode is ‘+’

In an electrolytic cell, which uses electrical energy for the propagation of a chemical reaction, In galvanic cells or electrochemical cells, which produce electrical energy by a chemical reaction, the anode is negative since it has a negative potential compared to the solution. The anode of a galvanic cell is zinc metal which is dipped in ZnSO4 solution. The Zn metal oxides to Zn2+ and gives two electrons into the external circuit.

• Cathode

Generally, the cathode is the electrode where reduction reaction takes place. This means the cathode gains electrons from the external circuit and gets reduced. The sign of cathode is ‘-’.

In galvanic cells, copper is a cathode which is dipped in CuSO4 solution. Cu2+ ions accept electrons from the external cell and are reduced to Cu metal and deposited on the cathode.

There are two types of cathodes, hot cathode and cold cathode. Cold cathodes are cathodes that are not electrically heated by a filament. Which emits more electrons than can be supplied by thermionic emission. Hot cathodes are heated by electric current passing through the filament. The cold cathode is used in discharge lamps, discharge tubes, and in some vacuum tubes.

Anode and Cathode in Electrolysis

During electrolysis a chemical reaction or change takes place by the passage of electricity through the circuit and an electrolytic cell is the device which converts electrical energy to chemical energy. The charge of anion and cation is positive and negative respectively in an electrolytic cell. Consider the electrolysis of molten NaCl.

The anode of the wire or plate is having excessive positive charge because it is connected to the positive terminal of the battery. Hence anions will tend to move towards the anode and give off the electrons to the anode and get oxidized. These electrons are given by anion pass to the external circuit. In the electrolysis of molten NaCl, two inert electrodes are dipped in molten NaCl solution. When the electricity passes, the anode develops an excess positive charge and Cl- ions from the solution move towards the anode, where they become oxidized to sodium metal.

The cathode connects to the negative terminal of the battery, and it contains an excess negative charge. Cations from the solution move towards it and get reduced by accepting the electrons from the external circuit. Conversely, in galvanic cells, the cation is a positive electrode. When molten NaCl is subjected to electrolysis when electricity is passed, Na+ Ions start moving towards the cathode, where it is reduced to become sodium metal.

Difference Between Anode and Cathode

Key Features

• Anode and cathode are electrodes used to make electrolytic and electrochemical cells.

• Anode is the electrode where oxidation reaction takes place, and in the cathode, reduction takes place.

• Anode is the electrode where electricity moves into the external circuit, and cathode is the electrode where electricity is given out.

• the charge of anode and cathode are positive and negative in an electrolytic cell and in the galvanic cell it is the opposite

Conclusion

Anode is the positive part of electrolyte where oxidation takes place and cathode is the negative part of the cell where reduction takes place. The symbol of anode and cathode are A and K respectively. In electrolysis anode is positively charged and cathode is negatively charged. Hence the sign of anode and cathode are ‘+’ and ‘-’ respectively.