[Chemistry Class Notes] on Electrode Pdf for Exam

Electrodes are good conductors of electricity. Electrodes are used to make contact between non-metallic parts such as electrolytes, semiconductors, air, etc. of the circuit. The word Electrode is made of two Greek words electron which means amber and hoods which means away. The word Electrode was coined by William Whewell. 

 

What is an Electrode? 

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 an anode. 

Electrodes are the main component of electrochemical cells. An Electrode must be a good conductor of electricity. Although inert Electrodes also exist which don’t take part in the reaction. An electrode can be of gold, platinum, carbon, graphite, metal, etc. The electrode provides a surface for oxidation reduction reactions in the cells. 

 

Cathode and Anode in Electrochemical Cells

In an electrochemical cell, an Electrode is referred to as either cathode or anode. The anode can be defined as the Electrode at which electrons leave the cell and oxidation takes place while the 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 these identities of cathode and anode are fixed. In these cells anode will always be negative or at this point oxidation will occur. While cathode will always be positive or at this rate reduction will occur. Example of a primary cell is a 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.

 

Types of Electrodes 

Electrodes are mainly of two types – Reactive Electrodes and Inert Electrodes 

Reactive Electrodes are those Electrodes which take part in the reaction taking place in the cell and can dissolve in the electrolyte. Examples 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 Electrodes – Carbon Electrode, Platinum Electrode etc.

 

Uses of Electrodes

• 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 the execution of electric chairs. 

• 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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