Course Content
CHAPTER 3: CLASSIFICATION OF ELEMENTS
Section Name Topic Name 3 Classification of Elements and Periodicity in Properties 3.1 Why do we Need to Classify Elements ? 3.2 Genesis of Periodic Classification 3.3 Modern Periodic Law and the present form of the Periodic Table 3.4 Nomenclature of Elements with Atomic Numbers > 100 3.5 Electronic Configurations of Elements and the Periodic Table 3.6 Electronic Configurations and Types of Elements: s-, p-, d-, f – Blocks 3.7 Periodic Trends in Properties of Elements
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CHAPTER 7: EQUILIBRIUM
Section Name Topic Name 7 Equilibrium 7.1 Equilibrium in Physical Processes 7.2 Equilibrium in Chemical Processes – Dynamic Equilibrium 7.3 Law of Chemical Equilibrium and Equilibrium Constant 7.4 Homogeneous Equilibria 7.5 Heterogeneous Equilibria 7.6 Applications of Equilibrium Constants 7.7 Relationship between Equilibrium Constant K, Reaction Quotient Q and Gibbs Energy G 7.8 Factors Affecting Equilibria 7.9 Ionic Equilibrium in Solution 7.10 Acids, Bases and Salts 7.11 Ionization of Acids and Bases 7.12 Buffer Solutions 7.13 Solubility Equilibria of Sparingly Soluble Salts
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CHAPTER 10: S-BLOCK ELEMENTS
Section Name Topic Name 10 The s-Block Elements 10.1 Group 1 Elements: Alkali Metals 10.2 General Characteristics of the Compounds of the Alkali Metals 10.3 Anomalous Properties of Lithium 10.4 Some Important Compounds of Sodium 10.5 Biological Importance of Sodium and Potassium 10.6 Group 2 Elements : Alkaline Earth Metals 10.7 General Characteristics of Compounds of the Alkaline Earth Metals 10.8 Anomalous Behaviour of Beryllium 10.9 Some Important Compounds of Calcium 10.10 Biological Importance of Magnesium and Calcium
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CHAPTER 12: CHARACTERIZATION OF ORGANIC COMPOUND
Section Name Topic Name 12 Organic Chemistry – Some Basic Principles and Techniques 12.1 General Introduction 12.2 Tetravalence of Carbon: Shapes of Organic Compounds 12.3 Structural Representations of Organic Compounds 12.4 Classification of Organic Compounds 12.5 Nomenclature of Organic Compounds 12.6 Isomerism 12.7 Fundamental Concepts in Organic Reaction Mechanism 12.8 Methods of Purification of Organic Compounds 12.9 Qualitative Analysis of Organic Compounds 12.10 Quantitative Analysis
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Class 11th Chemistry Online Class For 100% Result
About Lesson

Introduction

The reaction in which oxidation and reduction both occur simultaneously are called Redox reactions. Let us understand about oxidation and reduction. We have different concepts to understand oxidation and reduction.

Oxidation and Reduction

  • In terms of Classical concept

Oxidation: Oxidation is defined as “addition of oxygen or any electronegative element and removal of hydrogen or any electropositive element”.

Redox Reactions Class 11th Chemistry Notes and NCERT Solution

Please note the substance that undergo oxidation itself and reduce other is called reducing agent whereas the substance that undergo reduction itself and oxidize other is called oxidizing agent.

For example:-      CuO       + H2 –>      Cu + H2O

                   Copper Oxide  Hydrogen  Copper Water

In reaction, Cu is undergoing reduction and oxidizing hydrogen. Therefore, Cu is oxidizing agent and H is reducing agent.

“As in this reaction both oxidation and reduction occur simultaneously, therefore reaction is called redox reaction.”

  • In terms of Electron transfer concept

Oxidation: Is defined as loss of electrons that is:

                  M-electron  –>   M+

            Metal             Metal ion

Reduction: Is defined as gain of electrons that is given below.

N + electron  –>  N

       Non metal           non metal ion

Let us explain it more with the help of example:

Let’s consider equation: H2 + O2 — > H2O

We can see in this example that H atom as going from neutral to a positive state in water, the O atom goes from zero state to dinegative state in water. There is an electron transfer from H to O and consequently H is oxidized and O2 is reduced .The charge transfer is only partial or we can say that it is electron shift rather than calling it as complete loss of electron by H and gain by O.

Another example of Redox reaction in terms of electron transfer:

          Mg +         H2 –>       MgH2

     Magnesium Hydrogen  Magnesium Hydride

In this Magnesium is losing electrons, that is undergoing oxidation and hydrogen is gaining electrons therefore, it is undergoing reduction. Mg is Reducing agent in it and H is Oxidizing agent in it.

  • In terms of oxidation number

Oxidation number: It is defined as “residual charge that is present on atom when the atom is in combined state with other atoms”.

Rules to assign and calculate oxidation number

  1. The oxidation number of atoms in their elemental state is taken as zero.
  2. The oxidation number of mono-atomic atoms like Na+ etc is taken as 1.
  3. The oxidation number of Hydrogen is +1 when present with non metals and -1 when present with metals.
  4. The oxidation number of oxygen is -2 in most of the compounds but in peroxides it is -1.
  5. The metals always have oxidation number in positive and non metal in negative when present together in ionic compounds.
  6. In compounds that have two atoms with different electro negativities, the oxidation number of more electronegative is taken as –ve and for less electronegative it is taken as positive. For example: In OF2 the oxidation number of oxygen will be in positive and oxidation of fluorine will be in negative.
  7. In neutral compounds, the sum of all oxidation numbers is equal to zero.
  8. In complex ions, the sum of oxidation states of all the atoms is equal to the charge present on the complex.

Oxidation: It is defined as increase in oxidation number of an element.

   Mg  +        H2 –>       Mg2+ H2

Magnesium Hydrogen  MagnesiumHydride

In this, Magnesium oxidation number is increased from 0 to +2.Therefore, oxidation occurs.

Reduction: It is defined as decrease in oxidation number of an element.

For Example:- 

Fe3+ + e  –> Fe2+

Ferric Ion         Ferrous Ion

In this oxidation number of iron is reduced .Therefore, reduction occurs.

Redox reaction in terms of oxidation number

In this, Zinc is undergoing oxidation and act as reducing agent whereas Hydrogen is undergoing reduction and act as an oxidizing agent.

Zn0 +       H+Cl               –> Zn2+ + 0H2

Zinc  HydrogenChloride  Zinc Chloride  Hydrogen Gas

Redox Reactions Class 11th Chemistry Notes and NCERT Solution
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