Open In App

Oxidation and Reduction Reactions

Improve
Improve
Like Article
Like
Save
Share
Report

Oxidation and Reduction reactions are simply called Redox reactions. There are chemical reactions in which the oxidation number of the chemical species involved in the reaction changes. Oxidation and reduction Reactions involve a wide variety of processes. For example, oxidation-reduction reactions are so common that they can be the breathing process, burning of wood, rusting, fruit ripening, photosynthesis, and many more. Generally, these redox reactions involve the transfer of oxygen or hydrogen atoms.

In this article, we will learn about, What is Oxidation, What is Reduction, Examples of Oxidation Reductions Reactions, Oxidation and Reduction Half Reactions, Oxidation Number, and many more in detail.

What is Oxidation?

Oxidation is defined as the gain of oxygen or the loss of electrons or hydrogen. When an atom or molecule loses one or more electrons, an oxidation reaction occurs.

Some elements lose electrons faster than others, such as sodium, magnesium, and iron. We refer to them as easily oxidized chemicals.

What is Reduction?

Reduction is a process that involves the addition of hydrogen or any other electropositive element or the removal of oxygen or any other electronegative element, according to classical or older concepts.

Process through which an atom or an ion gains one or more electrons is known as reduction, according to the electronic concept.

Oxidant

Oxidant, also known as an oxidizing agent, is a substance that can accept electrons.  

Examples of Oxidants

In periodic table, molecules of electronegative elements (Oxygen) and halogens (Fluorine, Chlorine, Bromine, and Iodine) have high oxidation states. The following compounds have the highest Oxidation state, e.g: K2Cr2O7, KMnO4, HClO4, H2SO4, and KClO4.

Reductant

A reductant, which is also known as a reducing agent is a chemical substance that can donate electrons.

Examples of Reductants 

Metals such as sodium, Aluminum, and Zinc and non-metals like Calcium, Phosphorous, Sodium and Hydrogen gas are strong reducing agents.

Following compounds have lowest oxidation state, e.g: H2C2O4, FeSO4, HgCl4, SnCl2, H2S, and SO2.

Examples of Oxidation and Reduction Reactions

Various Examples of Oxidation and Reduction Reaction are,

Decomposition Reaction

Reaction which results in the decomposition or breakdown of the compounds is called a decomposition reaction.

AB ⇢ A + B

Example:

  • When Sodium Carbonate react decomposed to Na2O and CO2 as,

Na2CO3 ⇢ Na2O + CO2

  • When Water undergoes hydrolysis and decomposed into hydrogen gas and oxygen gas as shown below:

H2O ⇢ H2 + O2

Combination Reaction

The reaction which results in the combining of the compounds is known as a combination reaction. A combination reaction is just the opposite to a decomposition reaction.

A + B ⇢ AB

Example:

  • When iron combines with oxygen and forms Fe2O3. This is perfect example for combination reaction.

4 Fe + 3O2 ⇢ 2Fe2O3

Displacement Reaction

Reaction in which displacing of the components happens is usually known as a displacement reaction.

A + BC ⇢ AB + C

Example:

  • Here copper sulphate reacts with zinc and displacement happens which result in formation of copper and zinc sulphate.

CuSO4 + Zn ⇢ Cu + ZnSO4

Disproportionation Reaction

The reaction in which only a single reactant undergoes both oxidation and reduction is known as Disproportionation Reaction.

A + B  ⇢  AB

Example:

  • As the reaction shown below, Phosphorous undergoes both reduction and oxidation. So, this is an perfect example Disproportionation Reaction.

P4 + 3NaOH + 3H2O ⇢ 3NaH2PO2 + PH3

What is Oxidation and Reduction Half Reactions? 

Oxidation and Reduction Half Reactions

A reduction half and an oxidation half, which always occur together, make up redox reactions. While the oxidation half undergoes electron loss and an increase in oxidation number, the reduction half obtains electrons and the oxidation number decreases. 

Mnemonic used are OIL stands for “oxidation is loss” and RIG stands for “reduction is gain,” are simple ways to memorise this. The total number of electrons in a redox reaction remains unchanged. In the reduction half reaction, another species absorbs those that were released in the oxidation half reaction.

Oxidation Number

Oxidation Number is the power that appears on an atom when all other atoms are removed as ions. Oxidation numbers can be negative or positive.

Determination of Oxidation Number

Oxidation Number of any compound is calculated using the steps added below,

  1. Sum of the oxidation number of atoms in a neutral compound is equal to zero.
  2. Algebraic sum of the oxidation number of atoms in an ion is equal to the charge of that ion.
  3. Oxidation number of elements in their elementary state is equal to zero.
  4. Oxidation number of the element Fluorine is always equal to -1 in every compound.
  5. Oxidation number of Oxygen in every compound is -2, except in peroxides which are -1.
  6. Metal amalgam oxidation number is zero.
  7. Oxidation number of alkali metals is always +1 and the oxidation number of alkali earth metals is +2.
  8. For P-block elements, the highest oxidation number is always equal to their group number and their lowest oxidation number is equal to their group number minus 8.

For example: Lets find the Oxidation number of the compound K2Cr2O7

First consider the following oxidation number for the species present in the compound,

K2 = 2(+1) {Since oxidation number of potassium is +1}

Cr2= 2(x)

O7 = 7(-2) {Since oxidation number of oxygen is -2}

By adding them,

2 + 2(x) – 14 = 0

2x – 12 = 0

2x = 12

x = 12/2

= +6

Therefore, oxidation number of chromium in K2Cr2O7 is +6

How to Balance Redox Reaction?

Chemical reaction are balanced according to “Law of Conservation of Mass”. Chemical Equations which involve oxidation and reduction are balanced using following methods

  • Oxidation Number Method
  • Ion Electron Method (or Half Reaction Method)

Oxidation Number Method

Balancing chemical equations using the oxidation number method involves assigning oxidation numbers to each element in the reactants and products and then adjusting coefficients to ensure that the total increase and decrease in oxidation numbers are equal. The steps to balance a chemical equation using this method:

  • Step 1: Write down the unbalanced chemical equation.
  • Step 2: Assign oxidation numbers to each element in the reactants and products.
  • Step 3: Identify which elements are undergoing oxidation (increasing oxidation number) and which are undergoing reduction (decreasing oxidation number).
  • Step 4: Determine the change in oxidation number for each element undergoing oxidation or reduction.
  • Step 5: Balance the equation by adding coefficients to ensure that the total increase and decrease in oxidation numbers are equal on both sides of the equation.

Example: Balance chemical equation by Oxidation Number Method

CuO + NH3 → Cu + N2 + H2O

Ion Electron Method (or Half Reaction Method)

Ion-electron method, also known as the half-reaction method or the oxidation-reduction (redox) method, involves balancing chemical equations by dividing the equation into two half-reactions: the oxidation half-reaction and the reduction half-reaction. Here’s a step-by-step guide to balancing a chemical equation using this method:

  • Step 1: Write down the unbalanced chemical equation.
  • Step 2: Identify which elements are oxidized and which are reduced.
  • Step 3: Write separate half-reactions for oxidation and reduction.
  • Step 4: Balance each half-reaction individually by adding electrons (e-) to one side to balance the charge.
  • Step 5: Multiply each half-reaction by appropriate coefficients to equalize the number of electrons transferred.
  • Step 6: Add the balanced half-reactions together and cancel out any common terms.

Oxidation vs Reduction

  • Oxidation occurs when a reactant loses electrons during a reaction. Examples of oxidation reaction is, C + O2 → CO2
  • Reduction occurs when a reactant acquires electrons during a reaction. Examples of reduction reaction is, N2 + 3H2 → 2NH3

Uses of Oxidation and Reduction Reactions

Oxidation and Reduction Reactions are generally called redox reaction. Redox reactions are also used in a wide range of industries, including those in the biological, industrial, pharmaceutical, metallurgical, and agricultural fields. Examples of redox reactions in industrial processes include electroplating, the extraction of metals like aluminum, the production of chemical substances like caustic soda, the bleaching of wood pulp, metal corrosion, battery operation, and many more.

Redox reaction phenomena has been connected to a number of environmental challenges, including the ozone hole. So let’s investigate the fundamental concept of redox reactions. Redox reactions are made up of two reactions that happen simultaneously: oxidation and reduction. that is, concurrently.

Related Articles

Redox Reactions in terms of Electron Transfer

Redox Reactions and Electrode Processes 

Balancing Redox Reactions

Effects of Oxidation Reactions in Everyday Life

Oxidizing and Reducing Agents

What is Disproportionation Reaction

Oxidation and Reduction Reactions FAQs

What are Oxidation and Reduction Reactions?

Oxidation and Reduction reactions are also called the Redox Reaction. Redox reaction is the combination both oxidation half reaction and reduction half reaction.

What are Examples of Redox Reactions?

Examples of Redox Reaction,

  • 2KClO3 —-> 2KCl + 3O2
    • 2KClO3 —-> 2KCl (Reduction part)
    • 2KClO3 —-> 3O2  (Oxidation part)
  • Cl2 + 2 OH —-> ClO + Cl + H2O
    • Cl2 —-> ClO (Oxidation part)
    • Cl2 —-> Cl  (Reduction part)

What are Types of Redox Reactions?

There four types of redox reaction that are,

  • Displacement Reaction
  • Decomposition Reaction
  • Disproportionation Reaction
  • Combination Reaction

What are Oxidizing Agents?

Oxidising agent are substance that can accept electrons. Oxidizing agent acts as reducing substance.

Examples: Electronegative elements Oxygen and Halogens (Flourine, Chlorine, Bromine and Iodine) are oxidizing agent other examples are, K2Cr2O7, KMnO4, HClO4, H2SO4, KClO3.

What are Reducing Agents?

Reducing agents are substance that can donates electrons. Reducing agent acts as oxidising substance.



Last Updated : 07 Mar, 2024
Like Article
Save Article
Previous
Next
Share your thoughts in the comments
Similar Reads