Edited By Team Careers360 | Updated on Dec 19, 2024 11:23 PM IST
Chemistry deals with different types of matter and transforming one kind of matter into another. The various reactions are used to convert matter from one type to another. Redox Reactions are one of the most common types of reactions. A redox reaction is a reaction that comprises oxidation and reduction. When a redox reaction occurs, both oxidation and reduction reactions take place simultaneously. Redox reactions are involved in a wide range of physical and biological phenomena. Pharmaceutical, natural, industrial, metallurgical, and agricultural industries utilise redox reactions. The significance of redox reactions can be seen in the fact that redox processes include the combustion of various types of fuels for domestic, transportation, and other commercial purposes, electrochemical processes.
A redox reaction is a chemical reaction in which both reduction (gain of electrons) and oxidation (loss of electrons) occur simultaneously. It plays an important role in various chemical and biological processes, including respiration, photosynthesis, and industrial reactions like metal extraction and corrosion prevention. Redox reactions are often identified by changes in oxidation states of elements involved.
Oxidation Number
The oxidation number represents the hypothetical charge an atom would have if all bonds were ionic. It is used to track electron transfers in redox reactions. Rules for determining oxidation number includes assigning a value of 0 to free elements, matching the charge in ions, and following the standard rules for compounds and polyatomic ions. This concept helps balance redox equations systematically.
Displacement Reaction
In a displacement reaction, a more reactive element displaces a less reactive element from its compound. These reactions are classified into two types: metal displacement (e.g., zinc displacing copper from copper sulfate) and non-metal displacement (e.g., chlorine displacing bromine in bromide salts). Displacement reactions are a practical application of redox reactions, highlighting the reactivity series of elements.
The oxidation number (ON) is a concept used to track the transfer of electrons in redox reactions. It is assigned to elements in compounds based on a set of rules:
Free elements have an ON of 0.
For monoatomic ions, the ON equals the ion’s charge.
Oxygen typically has an ON of -2, except in peroxides (-1) and superoxides (-1/2).
Hydrogen is +1 when bonded to non-metals and -1 when bonded to metals. The concept is vital for identifying oxidized and reduced species in complex reactions and for balancing equations.
Displacement Reaction
Displacement reactions are a type of redox reaction where a more reactive element displaces a less reactive one from its compound. They are classified into two types:
Metal Displacement: A metal in its elemental form displaces another metal ion in a compound (e.g., Zn + CuSO4 → ZnSO4 + Cu).
Non-metal Displacement: A more electronegative non-metal displaces a less electronegative one (e.g., Cl2 + 2KI → 2KCl + I2). These reactions are widely used in metallurgy, electrochemical cells, and various industrial processes.
Balancing Redox Reactions
Balancing redox reactions ensures the conservation of mass and charge. The two primary methods are:
Oxidation Number Method: The changes in oxidation numbers are used to balance the equation.
Ion-Electron (Half-Reaction) Method: The oxidation and reduction half-reactions are balanced separately and combined. These methods are essential for accurately representing chemical processes in aqueous and non-aqueous systems.
Types of Redox Reactions
Redox reactions can be broadly classified into the following types:
Combination Reactions: Two or more reactants combine to form a single product. In many cases, one reactant is oxidized while the other is reduced.
Example: 2H2 + O2 → 2H2O
Decomposition Reactions: A single compound breaks down into two or more simpler substances. Often, one product is oxidized while the other is reduced. Example: 2H2O → 2H2 + O2
Disproportionation Reactions: A single substance undergoes both oxidation and reduction simultaneously.
Example: 2H2O2 → 2H2O + O2
Standard Electrode Potential (E°)
The standard electrode potential is a measure of the tendency of a chemical species to get reduced. It is measured in volts (V) under standard conditions (298 K, 1 M concentration, and 1 atm pressure).
A positive E° indicates a strong tendency to be reduced, acting as a good oxidizing agent.
A negative E° implies a strong tendency to be oxidized, acting as a good reducing agent.
Redox Reactions in Everyday Life
Redox reactions play an important role in various natural and industrial processes, such as:
Corrosion: The oxidation of metals, especially iron (rusting), is a detrimental redox reaction requiring mitigation.
Combustion: The burning of fuels (e.g., CH4+2O2→CO2+2H2O) involves redox reactions to release energy.
Electrochemical Applications of Redox Reactions
Redox reactions are fundamental to the working of electrochemical cells:
Galvanic Cells: Convert chemical energy into electrical energy using spontaneous redox reactions.
Electrolytic Cells: Use electrical energy to drive non-spontaneous redox reactions, as seen in electrolysis processes.
Batteries: Function on redox principles, with the flow of electrons from the reducing agent to the oxidizing agent generating electricity.
How To Prepare For Redox Reaction?
This chapter is a part of Physical chemistry. It is concept based and very easy to learn, there is no need to memorize any formula.
Before reading this chapter, first, you must have the basic knowledge of Oxidation-reduction and associated concepts form Chapter: Some Basic Concept Of Chemistry
Rest this complete chapter is very simple, just be regular and be consistent in your numerical practice.
Prescribed Books
First, you must finish the class XI and XII NCERT textbook and solve each and every example and unsolved question given in it. Then for advanced level preparation like JEE and NEET, you must follow O.P. Tandon. You must definitely solve the previous year's papers. Meanwhile, in the preparation, you must continuously give the mock tests for the depth of knowledge. Our platform will help you with a variety of questions for deeper knowledge with the help of videos, articles and mock tests.
Reactions of decomposition (Decomposition reactions)
Reactions to displacement (Displacement reactions)
Reactions of disproportionation (Disproportionation reactions )
2.Using fluorine, displacement reactions of Cl, Br, and I are rarely performed in aqueous solutions. Explain why?
Because fluorine is a reactive element, it replaces chloride, bromide, and iodide ions in solution, and it reacts with water, displacing oxygen.
3.What happens to hydrogen when it is oxidised?
Because of the partial loss of electrons, hydrogen gets oxidised. The hydrogen atoms in water have less electron density near them than they had in the H 2 molecule, even though the loss is not complete enough to create ions. Because of a partial gain of electrons, the oxygen is decreased.
4.Give one example of the Redox reaction.
Copper oxide and magnesium react to form copper and magnesium oxide.
5.Define oxidation, and what is an example of it?
Originally, the term "oxidation" was used to describe reactions in which an element reacts with oxygen. Example: The oxidation of magnesium occurs in the reaction between magnesium metal and oxygen to generate magnesium oxide.
6.What happens to an element's oxidation number during oxidation?
During oxidation, the oxidation number rises. When an element's oxidation number changes from 0 to 1, it is oxidised.
