Electrodes are good conductors of electricity. Electrodes are used to make contact between non-metallic part such as electrolyte, semiconductors, air etc. of the circuit. The word electrode is made of two Greek words elektron which means amber and hodos which means a way. The word electrode was coined by William Whewell.
An electrode can be defined as the point where current either enters or leaves the electrolyte or circuit. When the current leaves the electrode it is known as the cathode while when the current enters the electrode it is known as anode.
Electrodes are main component of electrochemical cells. It is must that an electrode should be a good conductor of electricity. Although inert electrode also exists which don’t take part in the reaction. Electrode can be of gold, platinum, carbon, graphite, metal etc. Electrode provides surface for oxidation reduction reactions in the cells.
In an electrochemical cell, an electrode is referred as either cathode or anode. The anode can be defined as the electrode at which electrons leave the cell and oxidation takes place while cathode can be defined as the electrode at which electrons enter the cell and reduction takes place. Any of the two electrodes can become either anode or cathode depending on the direction of current through the cell. The electrode that can function as anode in one cell while cathode in another is called bipolar electrode.
Primary cells are those electrochemical cells in which irreversible reactions occur that’s why in these identities of cathode and anode are fixed. In these cells anode will always negative or at this always oxidation will occur. While cathode will always be positive or at this always reduction will occur. Example of primary cell is galvanic cell.
Secondary cells or electrolytic cells are rechargeable it means reversible chemical reactions occur in these cells. In these cells anode is always positive while cathode is always negative.
Electrodes are mainly of two types – Reactive electrodes and Inert electrodes
Reactive electrodes are those electrodes which takes part in the reaction taking place in the cell and can dissolve in the electrolyte. Example of reactive electrode – copper electrode, silver electrode, zinc electrode, copper electrode etc. These are mainly used in potentiometric work.
Inert electrodes are those electrodes which do not take part in the reaction. Examples of inert electrode – Carbon electrode, Platinum electrode etc.
Electrodes are used to make contact between nonmetal components of a circuit in a cell.
Electrodes are used to measure conductivity.
These are used in fuel cells in vehicles.
These are used for medical purposes such as EEG, ECG, ECT and defibrillator.
These are used for electrophysiology techniques in biomedical research.
These are used in execution of electric chair.
These are used for electroplating.
These are used for arc welding.
These are used for grounding.
These are used in electrochemistry.
These are used for chemical analysis of substances.
These are used in membrane electrode assembly.
These are used in electroshock weapons.
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