## Sunday, May 24, 2015

### Ch.2 States of Matter - JEE Main Core Points for Revision

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

Matter exists in three physical states, solid, liquid, and gaseous.

Solid State: A substance in solid state has a definite size (volume) and a definite shape. As we know shape can be changed by applying force. It can be broken into pieces by hammering etc. The solids are hard and rigid. Some common solids in article share we see are stainless plates and glasses. We also use things like combs, mirrors, scooters and cars. Some of the elements that we see in solid shape are iron, aluminium, silver,and gold etc.

Liquid State: A liquid possesses definite volume but not a definite shape.

Gaseous State: A gas of a given mass, neither possesses a definite volume nor definite shape.

Contents of the Chapter

2.1 Intermolecular Forces Versus Thermal Energy of Three States of Matter
2.2 Measurable Properties of Gases
2.3 Gas Laws
2.4 Some Problems Involing Chemical Equations

2.6 Kinetic Molecular Theory of Gases
2.7 Maxwell-Boltzmann Distribution of molecular Speeds
2.8 Deviations from Ideal Gas Behavior - Real Gases
2.9 Liquification of Gases and Their  Critical Phenomena
2.10 Kinetic Molecular Model of Liquids
2.11 Properties of Liquids
2.12 Charateristics of Solids
2.13 Classification of Solids
2.14 Size andShare of Crystals
2.15 Types of Solids on the basis of Binding Forces
2.16 Intermolecular Forces

## 2.1 Intermolecular Forces Versus Thermal Energy of Three States of Matter

Particle concept of matter: According to this concept, all matter consists of tiny particles (atoms or molecules) which are constantly moving in all directions. These particles exert attractive forces upon one another called inter particle (intermolecular) forces.

## 2.2 Measurable Properties of Gases

1. Measurement of Mass
2. Measurement Volume
3. Measurement of Pressure
4. Measurement of Temperature

## 2.3 Gas Laws

1. Boyle's Law (Boyle Bday 25 January)
2. Charles' Law
4. The Combined Gas Lawor Ideal Gas Equation
5. Dalton's Law of Partial Pressures
6. Graham's Law of Diffusion or Effusion

1. Boyle's Law
2. Charles' Law
4. The Combined Gas Law or Ideal Gas Equation

2.4 Some Problems Involing Chemical Equations

### 6. Graham's Law of Diffusion or Effusion

When a cylinder of colourless hydrogen gas inverted over a cylinder of brown bromine vapour, after some time, we can see that both the cylinders become yellowish brown. This means hydrogen has travelled to the lower cylinder and bromine vapour moved to the upper cylinder.

Gases have the tendency to intermix and to form a homogeneous mixture. This property is known as diffusion.

Diffusion is defined as the process of intermixing of two or more gases, irrespective of density relationship adn without the help of external agency.

Graham's Law of Diffusion: The rate of diffusion of a gas is inversely proportional to the square root of its density or molar mass.

Effusion: Effusion is a special case of diffusion wherein a gas escapes through a small aperture from the vessel in which it is contained.

The rate of escape is inversely proportional to the square root of its density or molar mass.

## 2.6 Kinetic Molecular Theory of Gases

The important postulates of the Kinetic Molecular Theory

1. Gases consist of large number of minute particles called molecules.
2. The molecules are separated by large distances. The empty space in gas is so large that the actual volume occupied by the molecules is negligible when compared to the total volume of the gas.
3. Molecules of the gas are in state of random motion in all directions. In this motion they keep on colliding with each other and also the walls of the container.
4. Collisions between molecules as well as between molecules and walls of the container are elastic. It means there is no loss of energy in the system due to collisions. There may be redistribution of energy among molecules.
5. There are no forces of attraction or repulsion between molecules.
6. The pressure exerted by a gas on the walls of a container is due to the collision of the molecules.
7. The average kinetic energy of translational motion of gas molecules is directly proportional to the absolute temperature of the gas.

2.7 Maxwell-Boltzmann Distribution of molecular Speeds

Average, root mean square and most probable velocities and their relation with temperature;

Molecular Speeds

From the expression for kinetic temperature

Substitution gives the root mean square (rms) molecular velocity:

From the Maxwell speed distribution this speed as well as the average and most probable speeds can be calculated.

http://hyperphysics.phy-astr.gsu.edu/Hbase/kinetic/kintem.html

## 2.8 Deviations from Ideal Gas Behavior - Real Gases

Van der Wals' equation for real gases

## 2.9 Liquification of Gases and Their  Critical Phenomena

Critical temperature is the temperature above which a gas cannot be liquefied however high the pressure may be.

2.10 Kinetic Molecular Model of Liquids

1. Liquids are composed of molecules.
2. There are appreciable intermolecular forces between molecules that hold them together in the liquid.
3. Still, the intermolecular forces are weak, hence molecules of liquids are in constant random motion.
4. The average kinetic energy of molecules in a given sample is proportional to the absolute temperature.

## 2.11 Properties of Liquids

1. Volume
2. Density
3.Compressibility
4. Diffusion
5. Evaporation
6. Enthalpy of vaporisastion

7.Vapour Pressure

When a liquid is placed in a vessel and is covered with jar, from the liquid evaporation takes place and the vapour of the liquid or molecules of the liquid in gap form fill the available space. As the evaporation takes place over a period of time, the number of gaseous molecules goes up. As evaporation is taking place some molecules in the gaseous phase collide with the surface of the liquid and become liquid molecules. Thus both evaporation and condensation take place simultaneously. But initially there is more evaporation and less condensation. At the some stage, rate of evaporation equals rate of condensation and equilibrium is established between gas and liquid phases. The pressure exerted by the vapours at the equilibrium stage is called vapour pressure.

Definition
The pressure exerted by the vapours above the liquid surface (in a closed vessel) in equilibrium with the liquid at a given temperature is called vapour pressure.

Vapour pressure changes from liquid to liquid. It depends on intermolecular forces. if the forces in a liquid are weak, there is more gas formation and hence more vapour pressure.

A higher temperature there is more gas formation and hence for the same liquid vapour pressures increase with temperature.

8. Boiling
9. Surface tension
10. Viscosity

## 2.12 Charateristics of Solids

1. Solids are rigid and have definite shape

## 2.13 Classification of Solids

1. Crystalline Solids  2. Amorphous Solids

## 2.14 Size and Share of Crystals

Law of constancy of interfacial angles of a crystal,

## 2.15 Types of Solids on the basis of Binding Forces

1. Molecular crystals
2. Iconic crystals
3. Covalent crystals
4. Metallic crystals

## 2.16 Intermolecular Forces

In addition to normal covalent bond, ionic bond, and metallic bond, there are weak attractive intermolecular forces which occur in all kinds of molecular solids. These are present in case of non-polar molecules such as H2, O2, CO2, CH4 etc. also.

These are classified as:
i) Dipole-dipole forces
ii) Dipole induced dipole forces
iii) Instantaneous dipole-instantaneous induced dipole forces (called London forces)
iv) Hydrogen bonding

### JEE Main - Chapters - Modern Chemistry for Class XI by Dr. S.P. Jauhar

1. Some basic concepts of chemistry

Study Guide - 15 Days

Core Revision Points

Notes

2. States of Matter

Study Guide - 13 Days

Core Revision Points

Notes

3. Atomic Structure

Study Guide - 12 Days

Core Revision Points

Notes

4. Classification of Elements and Periodicity in Properties

Study Guide

Core Revision Points

5. First Law of Thermodynamics and Chemical Energetics

Study Guide

Core Revision Points

Notes

6. Chemical Bonding and Molecular Structure

Study Guide

Core Revision Points

Notes

7. Equilibrium I – Equilibrium Process and Phase Equilibria

Study Guide

Core Revision Points

Notes

8. Equilibrium II – Ionic Equilibrium in Solutions

Study Guide

Core Revision Points

Notes

9. Redox Reactions

Study Guide

Core Revision Points

Notes

10. Principles and Processes of Extraction of Elements

Study Guide

Core Revision Points

Notes

11. Hydrogen

Study Guide

Core Revision Points

12. s-Block Elements

Study Guide

Core Revision Points

Notes

13. Some p-Block Elements

Study Guide

Core Revision Points

Notes

14. Organic Chemistry: Some Basic Principles

Study Guide

Core Revision Points

15. Hydrocarbons

Study Guide

Core Revision Points

Alkanes - Revision Notes

Alkenes

Alkynes

Aromatics - Benzene

16. Purification and Characterisation of Organic Compounds

Study Guide

Core Revision Points

17. Organic Compounds with Functional Groups Containing Halogens

Study Guide

Core Revision Points

Alkyl halides

18. Environmental Pollution

Study Guide

Core Revision Points

Updated 24 May 2015
First posted 20 Dec 2014

## Saturday, May 23, 2015

### 18. Chemistry in Everyday Life - JEE Main - Core Revision Points

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

Sections in the chapter – Jauhar

18.1 Chemical medicines and health care
18.2 Dyes
18.3 Chemicals in Cosmetics
18.5 Chemicals in food
18.6 Detergents
18.7 Insect repellants: pheromones and sex attractants
18.8 Chemistry of rocket propellants

Sections in the chapter – Jauhar

18.1 Chemical medicines and health care
18.2 Dyes
18.3 Chemicals in Cosmetics
18.5 Chemicals in food
18.6 Detergents
18.7 Insect repellants: pheromones and sex attractants
18.8 Chemistry of rocket propellants

### 17. Biomolecules - JEE Main - Core Revision Points

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

Sections in the chapter - Jauhar

17.1 The Cell
17.2 Energy cycle
17.3 Carbohydrates
17.4 Monosaccharides
17.5 Disaccharides
17.6 Polysaccharides
17.7 Important functions of carbohydrates
17.8 Aminoacids
17.9 Structure of alpha-Amino acids
17.10 Peptides and proteins
17.11 Proteins
17.12 Classification of proteins
17.13 Structure of proteins
17.14 Forces that stabilize protein structures
17.15 Native states and denaturation of proteins
17.16 Enzymes
17.17 Nucleic acids
17.18 Structure of DNA
17.19 Lipids
17.20 Hormones
17.21 Vitamins

Sections in the chapter - Jauhar

17.1 The Cell
17.2 Energy cycle
17.3 Carbohydrates
17.4 Monosaccharides
17.5 Disaccharides
17.6 Polysaccharides
17.7 Important functions of carbohydrates
17.8 Aminoacids
17.9 Structure of alpha-Amino acids
17.10 Peptides and proteins
17.11 Proteins
17.12 Classification of proteins
17.13 Structure of proteins
17.14 Forces that stabilize protein structures
17.15 Native states and denaturation of proteins
17.16 Enzymes
17.17 Nucleic acids
17.18 Structure of DNA
17.19 Lipids
17.20 Hormones
17.21 Vitamins

### 16. Polymers - JEE Main - Core Revision Points

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

## Sections in the chapter - Jauhar

16.1 Polymers
16.2 Classification of Polymers
16.3 General methods of Polymerisation
16.5 Copolymers
16.6 Natural rubber
16.7 Condensation of Polymers
16.8 Molecular masses of Polymers
16.9 Biopolymers
16.11 Some Commercially important Polymers

## Sections in the chapter - Jauhar

16.1 Polymers
16.2 Classification of Polymers
16.3 General methods of Polymerisation
16.5 Copolymers
16.6 Natural rubber
16.7 Condensation of Polymers
16.8 Molecular masses of Polymers
16.9 Biopolymers
16.11 Some Commercially important Polymers

### 15. Organic Compounds with functional Groups Containing Nitrogen (Nitro, Amino, Cyano and Diazo Compounds) - JEE Main - Core Revision Points

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

Sections in the chapter spread over three parts

Part A Nitro compounds

15A.1 Nomenclature of nitro compounds
15.2 Preparation of nitro compounds
15.3 Physical properties of nitro compounds
15.4 Chemical properties of nitro compounds
15.5 Uses of nitro compounds
15.6 Distinction between nitroalkanes and alkyl nitrites
15.7 Some commercially important compounds

Part B Amines

15B.1 Nomenclature of amines
15.2 Isomerism in amines
15B.3 Preparation of amines
15B.4 Industrial Preparation of amines
15B.5 Physical properties of amines
15B.5B Chemical properties of amines
15B.6 Distinction between primary, secondary and tertiary amines
15B.7 Separation of mixture of primary, secondary and tertiary amines
15B.8 Some commercially important compounds
15B.9 Distinction between pairs of compounds

Part C. Cyanides and Isocyanides & Diazonium salts

Cyanides and Isocyanides
15C.1 Nomenclature of Cyanides and Isocyanides
15.2 Preparation of Cyanides and Isocyanides
15.3 Physical properties of Cyanides and Isocyanides
15.4 Chemical properties of Cyanides and Isocyanides
15.5 Uses of Cyanides and Isocyanides
15.6 Distinction between cyanide and ethyl isocyanide
Practice Problems 15C.1 to 15C.4

Diazonium salts

15.7 Nomenclature Diazonium salts
15.8 Preparation of Diazonium salts
15.9 Physical properties of Diazonium salts
15.10 Chemical properties of Diazonium salts
15.11 Importance of Benzene Diazonium salts in synthetic organic chemistry

Sections in the chapter spread over three parts

Part A Nitro compounds

15A.1 Nomenclature of nitro compounds
15.2 Preparation of nitro compounds
15.3 Physical properties of nitro compounds
15.4 Chemical properties of nitro compounds
15.5 Uses of nitro compounds
15.6 Distinction between nitroalkanes and alkyl nitrites
15.7 Some commercially important compounds

Part B Amines

15B.1 Nomenclature of amines
15.2 Isomerism in amines
15B.3 Preparation of amines
15B.4 Industrial Preparation of amines
15B.5 Physical properties of amines
15B.5B Chemical properties of amines
15B.6 Distinction between primary, secondary and tertiary amines
15B.7 Separation of mixture of primary, secondary and tertiary amines
15B.8 Some commercially important compounds
15B.9 Distinction between pairs of compounds

Part C. Cyanides and Isocyanides & Diazonium salts

Cyanides and Isocyanides
15C.1 Nomenclature of Cyanides and Isocyanides
15.2 Preparation of Cyanides and Isocyanides
15.3 Physical properties of Cyanides and Isocyanides
15.4 Chemical properties of Cyanides and Isocyanides
15.5 Uses of Cyanides and Isocyanides
15.6 Distinction between cyanide and ethyl isocyanide
Practice Problems 15C.1 to 15C.4

Diazonium salts

15.7 Nomenclature Diazonium salts
15.8 Preparation of Diazonium salts
15.9 Physical properties of Diazonium salts
15.10 Chemical properties of Diazonium salts
15.11 Importance of Benzene Diazonium salts in synthetic organic chemistry

### 11. Nuclear Chemistry - JEE Main - Core Revision Points

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

11.1 Natural Radioactivity:Discovery and historical development
11.2 Nature and characteristics of Radioactive rays
11.3 Nuclear structure and nuclear forces
11.4 Nuclear reactions and group displacement law
Practice Problems: 11.1 to 11.8
P.P. 11.9 to 11.16
11.7 Artificial transmutation of elements
P.P. 11.17 to 11.20
11.9 Nuclear energy
P.P. 11.21 to 11.24
11.10 Nuclear fission
11.11 Atomic bomb and Nuclear reactor
11.12 Nuclear Fusion
P.P. 11.25 to 11.26
11.13 Synthetic elements
11.14 Radioactive isotopes and their uses
P.P. 11.27 to 11.38

11.1 Natural Radioactivity:Discovery and historical development
11.2 Nature and characteristics of Radioactive rays
11.3 Nuclear structure and nuclear forces
11.4 Nuclear reactions and group displacement law
Practice Problems: 11.1 to 11.8
P.P. 11.9 to 11.16
11.7 Artificial transmutation of elements
P.P. 11.17 to 11.20
11.9 Nuclear energy
P.P. 11.21 to 11.24
11.10 Nuclear fission
11.11 Atomic bomb and Nuclear reactor
11.12 Nuclear Fusion
P.P. 11.25 to 11.26
11.13 Synthetic elements
11.14 Radioactive isotopes and their uses
P.P. 11.27 to 11.38

### JEE Main - Chapters - Modern Chemistry for Class XII by Dr. S.P. Jauhar

1. Atomic Structure and Chemical Bonding

Study Plan  - May  - 15 days   1 to 15 May

Core Revision Points

2. Solid State

Study Plan - May - 10 Days   16 to 25 May

Core Revision Points

3. Solutions

Study Plan  15 Days   26 May to 30 May - 1 June to 10 June

Core Revision Points

4. Chemical Thermodynamics

Study Plan -  15 Days  June  11 to 25

Core Revision Points

5. Electrochemistry

Study Plan  -  15 Days June  26 to 30, July 1 to 10

Core Revision Points

6. Chemical Kinetics

Study Plan - 15 Days  July 11 to 25

Core Revision Points

7. Surface Chemistry

Study Plan - 10 days  July 25 to 30, 1 to 5 August

Core Revision Points

8. p-Block Elements

Study Plan - 15 days  6 to 20 August

Core Revision Points

9. d and f -Block Elements

Study Plan - 10 Days  21 to 30 August

Core Revision Points

10. Co-ordination Compounds and Organometallics

Study Plan - 10 Days   1 to 10 September

Core Revision Points

11. Nuclear Chemistry

Study Plan - 15 Days   11 to 25 September

Core Revision Points

A Preview of Organic Chemistry  - 9 Days of slack time is there in the year.

Study Plan

Core Revision Points

12. Stereochemistry

Study Plan - 11 Days  26 to 30 September   1 to 6 October

Core Revision Points

13. Organic Compounds with functional Groups Containing Oxygen - I (Alcohols, Phenols and Ethers)

Study Plan - 15 Days  - 7 to 21 Ocotber

Core Revision Points

14. Organic Compounds with functional Groups Containing Oxygen – II (Aldehydes, Ketones, Carboxylic Acids and their Derivatives)

Study Plan - 15 Days - 22 to 30 October,  1 to 6 November

Core Revision Points

15. Organic Compounds with functional Groups Containing Nitrogen (Nitro, Amino, Cyano and Diazo Compounds)

Study Plan - 15 Days  - 7 to 21 November

Core Revision Points

16. Polymers

Study Plan - 10 Days  - 22 to 30 November, 1 December

Core Revision Points

17. Biomolecules

Study Plan - 10 Days  - 2 to 11 December

Core Revision Points

18. Chemistry in Everyday Life

Study Plan - 10 Days  - 12 to 21 December

Core Revision Points

Updated 23 May 2015
First published on 20 Dec 2014

### JEE Main 2016 - 2015 - 2016 Chemistry Study Plan

1. Atomic Structure and Chemical Bonding

Study Plan  - May  - 15 days   1 to 15 May

Core Revision Points

2. Solid State

Study Plan - May - 10 Days   16 to 25 May

Core Revision Points

3. Solutions

Study Plan  15 Days   26 May to 30 May - 1 June to 10 June

Core Revision Points

4. Chemical Thermodynamics

Study Plan -  15 Days  June  11 to 25

Core Revision Points

5. Electrochemistry

Study Plan  -  15 Days June  26 to 30, July 1 to 10

Core Revision Points

6. Chemical Kinetics

Study Plan - 15 Days  July 11 to 25

Core Revision Points

7. Surface Chemistry

Study Plan - 10 days  July 25 to 30, 1 to 5 August

Core Revision Points

8. p-Block Elements

Study Plan - 15 days  6 to 20 August

Core Revision Points

9. d and f -Block Elements

Study Plan - 10 Days  21 to 30 August

Core Revision Points

10. Co-ordination Compounds and Organometallics

Study Plan - 10 Days   1 to 10 September

Core Revision Points

11. Nuclear Chemistry

Study Plan - 15 Days   11 to 25 September

Core Revision Points

A Preview of Organic Chemistry  - 9 Days of slack time is there in the year.

Study Plan

Core Revision Points

12. Stereochemistry

Study Plan - 11 Days  26 to 30 September   1 to 6 October

Core Revision Points

13. Organic Compounds with functional Groups Containing Oxygen - I (Alcohols, Phenols and Ethers)

Study Plan - 15 Days  - 7 to 21 Ocotber

Core Revision Points

14. Organic Compounds with functional Groups Containing Oxygen – II (Aldehydes, Ketones, Carboxylic Acids and their Derivatives)

Study Plan - 15 Days - 22 to 30 October,  1 to 6 November

Core Revision Points

15. Organic Compounds with functional Groups Containing Nitrogen (Nitro, Amino, Cyano and Diazo Compounds)

Study Plan - 15 Days  - 7 to 21 November

Core Revision Points

16. Polymers

Study Plan - 10 Days  - 22 to 30 November, 1 December

Core Revision Points

17. Biomolecules

Study Plan - 10 Days  - 2 to 11 December

Core Revision Points

18. Chemistry in Everyday Life

Study Plan - 10 Days  - 12 to 21 December

Core Revision Points

23 May 2015

## Thursday, May 21, 2015

### 17. Organic Compounds with Functional Groups Containing Halogens - JEE Main - Core Points for Revision

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

Sections in the Chapter of Jauhar

17.1 Classification of halogen Derivatives of Hydrocarbons
17.2 Nomenclature of Haloalkanes
17.3 Nomenclature of Aryl Halides
17.4 isomerism in Haloalkanes
17.5 Methods of Preparation of Haloalkanes
17.6 General Methods of Preparation of Haloarenes
17.7 Physical Properties of haloalkanes
17.8 Physical Properties of haloarenes
17.9 Nature of C-X Bond
17.10 Chemical Properties of Haloalkanes
17.11 Chemical Properties of Haloarenes
17.12 Some Commercially Important Compounds
17.13 Analysis and Difference Between Haloalkanes and Haloarenes

### Chapter 16. Purification and Characterisation of Organic Compounds - JEE Main Core Revision Points

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

Text Book Modern's abc of Chemistry CBSE Class XI

Sections in the chapter

16.1 Purification of Organic Compounds
16.2 Qualitative Analysis
16.3 Quantitative Analysis
16.4 Determination of Molecular Mass
16.5 Mass Spectrometer
16.6 Empirical Formula and Molecular Formula
16.7 Modern Methods of Structural Elucidation

### 15. Hydrocarbons - JEE Main - Core Points for Revision

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

15.1 Classification of Hydrocarbons
15.2 Alkanes
15.3 Nomenclature of Alkanes
15.4 Conformations in Hydrocarbons
15.5 Preparation and Properties of Alkanes

Chemistry of Alkenes
15.6 Nomenclature of Alkenes
15.7 Isomerism in Alkenes
15.8 Stability of of Alkenes
15.9

Chemistry of Alkynes

15.10 Isomerism in Alkynes
15.11 Preparation and Properties of Alkynes

15.12 Dienes
15.13 Stability of Conjugated Dienes
15.14 Delocalization of Electrons
15.15 Electrophilic addition to Conjugated Dienes

Chemistry of Aromatic Hydrocarbons

15.16 Arenes or Aromatic Hydrocarbons
15.17 Nomenclature
15.18 Stability and Structure of Benzene
15.19 Isomerism in Arenes
15.20 Aromaticity (Huckel Rule)
15.21 Sources of Aromatic Hydrocarbons
15.22 Preparation of Benzene and Its Homologues
15.23 Properties of Benzene and Its Homologues
15.24 Mechanism of Electrophilic Substitution Reactions of Benzene
15.25 Directive Influence of Substituents and Their Effect on reactivity
15.26 Polynuclear Hydrocarbons

Chemistry of Petroleum and Petrochemicals

15.27 Petroleum and Composition of Crude Oil
15.28 Fractional Distillation of Crude Oil
15.29 Quality of Gasoline – Octane Number
15.30 LPG and CNG
15.31 Cracking and Reforming
15.32 Petrochemicals

### 13. Some p-Block Elements - JEE Main - Core Points for Revision

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

Sections in the Chapter

Chemistry of Boron and Its compounds

13.1 Boron
13.2 Compounds of Boron

Chemistry of Carbon and its Compounds

13.3 Carbon
13.4 Compounds of Carbon

Chemistry of Nitrogen and its Compounds

13.5 Nitrogen
13.6 Compounds of Nitrogen

Chemistry of Oxygen and its Compounds

13.7 Oxygen
13.8 Simple Oxides
13.9 Ozone

### 12. s-Block Elements - JEE Main - Core Points for Revision

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

Sections in Jauhar's Book

12.1 Abundance and Occurrence
12.2 Anomalous Properties of First Element in Each Group
12.3 Diagonal Relationship

Chemistry of Alkali Metals

12.4 Occurrence
12.5 General Characteristics of Alkali Metals
12.6 General Characteristics of Compounds of Alkali Metals
12.7 Anomalous Behavior of Lithium
12.8 Diagonal Relationship

Chemistry of Li and Na and Its Compounds

12.9 Occurrence of Lithium and Sodium
12.10 Extraction of Lithium and Sodium
12.11 Some Important Compounds of Sodium

Chemistry of Alkaline Earth Metals

12.12 Occurrence
12.13 General Characteristics of Alkaline Earth Metals
12.14 General Characteristics of Compounds of Alkaline Earth Metals
12.15 Differences between Beryllium and Magnesium
12.16 Diagonal Similarities of Beryllium and Aluminium
12.17 Occurrence of Magnesium
12.18 Compounds of Magnesium and Calcium
12.19 Industrial Uses of Limestone and Lime
12.20 Cement

### Chapter 11. Hydrogen - JEE Main - Core Points for Revision

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

Sections in the Chapter - Jauhar

1. Unique position of hydrogen in the periodic table
2. Occurrence of hydrogen
3. Isotopes of hydrogen
4. Dihydrogen
5. Hydrides
6. Water
7. Heavy Water
8. Hard and Soft Water
9 Hydrogen Peroxide
10 Liquid Hydrogen as a Fuel
11 Hydrogen Economy

### JEE Main - Core Points for Revision - 10. Principles and Processes of Extraction of Elements

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

Sections in the chapter

1. Origin of Elements
2. Distrubution of elements on earth
3. Elements of biological world
4. Ocean as a source of elements
5. Modes of occurrence of metals
6. Occurrence of metal: Minerals and ores
7. Mineral wealth of India
8. Extraction of elements
9. Extraction of nonmetallic elements
10. Extraction of metals: Metallurgy
11. Thermodynamics of metallurgy

### JEE Main - Core Points for Revision - 9. Redox Reactions

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

Sections in the Chapter

9.1 Oxidation and Reduction Reactions
9.2 Oxidation and Reduction Reactions as Electrons Transfer reactions
9.3 Redox Reactions in Aqueous Solutions
9.4 Oxidation Number
9.5 Redox Reactions in Terms of Oxidation Number
9.6 Oxidation Number and Nomenclature
9.7 Balancing Oxidation-Reduction Reactions
9.8 Indirect Redox Reactions – Electrochemical Cells
9.9 Representation of an Electrochemical Cell
9.10 Electrode Potential
9.11 E.M.F. or Cell Potential of a Cell
9.12 Measurement of Electrode Potentials
9.13 Electrochemical Series
9.14 Stoichiometry of Redox Reactions
9.15 Redox Reactions and Their Important Applications in Human Activity

### JEE Main - Core Points for Revision - Ch. 8. Equilibrium II – Ionic Equilibrium in Solutions

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

Sections in the Chapter

8.1 Acid-base Concepts
8.2 Acid- base Equilibria and Ionization of Acids and Bases
8.3 Ionization of Water – Ionic Product of Water
8.4 Expressing Hydrogen Ion Concentration – pH Scale
8.5 Polyprotic Acids and Bases
8.6 Hydrolysis of Salts
8.7 Acid base Titrations and Indicators
8.8 Solubility Product
8.9 Buffer Solution

### JEE Main - Core Points for Revision - 7. Equilibrium I – Equilibrium Process and Phase Equilibria

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Contents

7.1 Equilibrium and Its dynamic nature
7.2 Equilibrium in Physical Processes
7.3 Equilibria involving Chemical Systems
7.4 Law of Chemical equilibrium and equilibrium Constant
7.5 Types of Chemical Equilibria
7.6 Applications of Equilibrium Constant
7.7 Factors Which change the State of Equilibrium – Le Chatelier’s Principle
7.8 Applications of Le Chatelier’s Principle of Physical Equilibrium

### JEE Main - Core Revision Points - 5. First Law of Thermodynamics and Chemical Energetics

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

JEE Syllabus

Energetics:

First law of thermodynamics;
Internal energy, work and heat,
pressure-volume work;
Enthalpy,
Hess's law;
Heat of reaction, fusion and vapourization;
Second law of thermodynamics;
Entropy;
Free energy;
Criterion of spontaneity.
------------------

Sections in the Chapter - Jauhar

5.1 Some Basic Terms and Concepts
5.2 Modes of Transference of Energy between System and Surroundings
5.3 Internal Energy and Internal Energy Change
5.4 Zeroth Law of Thermodynamics
5.5 Law of Conservation of Energy: First Law of Thermodynamics
5.6 Enthalpy and Enthalpy change
5.7 Exothermic and Endothermic Reactions
5.8 Heat Capacity
5.9 Measurement of Internal Energy (Delta U) and enthalpy (Delta H) of a Reaction
5.10 Thermochemical Equations
5.11 Enthalpy Changes in Chemical Reactions
5.12 Enthalpy of Formation
5.13 enthalpy of Combustion
5.14 Enthalpy of Neutralization
5.15 Enthalpy of phase Transitions
5.16 Hess’s Law of Constant Heat Summation
5.17 Bond Enthalpy
5.18 Sources of Energy
5.19 Alternative Energy Sources

5.1 Some Basic Terms and Concepts
5.2 Modes of Transference of Energy between System and Surroundings
5.3 Internal Energy and Internal Energy Change
5.4 Zeroth Law of Thermodynamics
5.5 Law of Conservation of Energy: First Law of Thermodynamics

First law of thermodynamics;

Energy cannot be created or destroyed.

U = q + w

Internal energy of matter is equal to kinetic energy and potential energy.

The change in internal energy is equal to heat transferred and work done between the system and the surroundings.

Pressure volume work: If the pressure is constant and the matter expands, the work done is given by p * change in volume. This in termed as pressure volume work.

Enthalpy = U + pv

5.6 Enthalpy and Enthalpy change
5.7 Exothermic and Endothermic Reactions
5.8 Heat Capacity
5.9 Measurement of Internal Energy (Delta U) and enthalpy (Delta H) of a Reaction
5.10 Thermochemical Equations
5.11 Enthalpy Changes in Chemical Reactions
5.12 Enthalpy of Formation
5.13 enthalpy of Combustion
5.14 Enthalpy of Neutralization
5.15 Enthalpy of phase Transitions

5.16 Hess’s Law of Constant Heat Summation

Hess's Law

Hess's Law states that the enthalpy change for a reaction that occurs in many steps is the same as if it occurred in one step. Another way to put this is if several reactions add up to some total reaction, then their enthalpy changes will add up to the enthalpy change for the total reaction.

5.17 Bond Enthalpy
5.18 Sources of Energy
5.19 Alternative Energy Sources

First law of thermodynamics;

Energy cannot be created or destroyed.

U = q + w

Internal energy of matter is equal to kinetic energy and potential energy.

The change in internal energy is equal to heat transferred and work done between the system and the surroundings.

Pressure volume work: If the pressure is constant and the matter expands, the work done is given by p * change in volume. This in termed as pressure volume work.

Enthalpy = U + pv

Hess's Law

Hess's Law states that the enthalpy change for a reaction that occurs in many steps is the same as if it occurred in one step. Another way to put this is if several reactions add up to some total reaction, then their enthalpy changes will add up to the enthalpy change for the total reaction.

### IIT JEE Ch.3. ATOMIC STRUCTURE Core Points for Revision

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

JEE Syllabus

Atomic structure
Bohr model, spectrum of hydrogen atom, quantum numbers;
Wave-particle duality, de Broglie hypothesis;
Uncertainty principle;
Quantum mechanical picture of hydrogen atom (qualitative treatment), shapes of s, p and d orbitals;
Electronic configurations of elements (up to atomic number 36);
Aufbau principle;
Pauli's exclusion principle and Hund's rule;
----------------

Jauhar Chapter Contents

3.1 Fundamental Particles
3.2 arranging electrons and protons in an atom
3.3 Rutherford's Scattering Experiment
3.4 Concept of Atomic Number
3.5 Developments Leading to the Bohr Model of Atom
3.6 Nature of LIght and Electromagnetic Radiation
3.7 Particle Nature of Electromagnetic Radiation and Planck's Quantum Theory
3.8 Atomic Spectra
3.9 Failure of Rutherford Model
3.10 Concepts of Energy Levels or Orbits
3.11 Modern Concept of Structure of Atom
3.12 Wave Mechanical Model of Atom
3.13 Quantum Numbers
3.14 Pauli's Exclusion Principles
3.15 Shapes of Orbitals
3.16 Energy Level Diagram for Electrons in an Atom
3.17 Electron Configurations of Atoms

In 1913, Niels Bohr proposed a model of the atom. He proposed that the electrons in an atom could only be in certain orbits, or energy levels, around the nucleus. Refinement of Bohr theory led to the modern theory of atomic structure based on quantum mechanics.

Bohr's model is based on particle theory.

As wave-particle duality which says that all micromatter particle exhibit dualitya new model is proposed.

Debroglie p = h/Î»

Uncertainty principle Î”p* Î”x ≥h/4Ï€

The quantum mechanics model

Principal quantum number-Shell,Azimuthal quantum number-sublevel,Magnetic quantum number-orbital, spin quantum number

The orbits are called as shells. The energy level of orbits or shells increases as they increase in distance from the nucleus of the atom. The orbits or shells are represented by numbers as 1,2,3,4,5,6 or 7. They are represented by letters as K,L,M,N,O,P,Q.

Sublevel of an Orbit

The energy levels, or orbits or shells are further divided into sublevels, or subshells. These subshells are designated by letters: s for the first possible sublevel, p for the second possible sublevel, d for the third, f for the fourth, g for the fifth, and from here on they simply go in alphabets.

The number of sublevels of each energy level is equal to the number of the energy levels. This means energy level 1, the K shell will have only one sub levels – s sublevel. The energy level 2, the L shell will have 2 sub levels – s and p.

Orbitals

Sublevels have further divisions called orbitals. Electrons are found in these orbitals. Each orbital contains two electrons.

“s” sublevel has only one orbital. “p” sublevel has 3 orbitals. “d” sublevel has 5 orbitals. “f” sublevel has 7 orbitals.

The two electons in each orbital spin in different directions.

Electrons occupy the lowest energy sublevels that are available. This is known as ‘aufbau’ order or principles.

Hund’s rule says that, for any set of orbitals of equal energy say p orbitals of orbit 2, there is one electron is each orbital before the second electron enters or occupies an orbital.

The energy level of some sublevels at higher orbits is less than the some sublevels at lower orbitals. This fact is to be kept in mind when electron configuration is determined for any atom. The increasing order of energy levels of sublevels is:

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f*, 5d, 6p, 7s, 5f*, 6d, 7p, 8s

Jauhar Chapter Contents

3.1 Fundamental Particles
3.2 arranging electrons and protons in an atom
3.3 Rutherford's Scattering Experiment
3.4 Concept of Atomic Number
3.5 Developments Leading to the Bohr Model of Atom
3.6 Nature of Light and Electromagnetic Radiation
Particle Nature of Electromagnetic Radiation and Planck's Quantum Theory
3.8 Atomic Spectra
3.9 Failure of Rutherford Model
3.10 Concepts of Energy Levels or Orbits
3.11 Modern Concept of Structure of Atom
3.12 Wave Mechanical Model of Atom
3.13 Quantum Numbers
3.14 Pauli's Exclusion Principles

Pauli's exclusion principle: No two electrons can have all four same quantum numbers

3.15 Shapes of Orbitals

Shape of Orbitals
1. Spherical shape for s.
2. Dumbbell shape for orbitals of p.
3. Four-lobed shape for orbitals of d.
4. Complex shape for all orbitals of higher sublevels.

3.16 Energy Level Diagram for Electrons in an Atom
3.17 Electron Configurations of Atoms

Updated 21 May 2015
Published first 19 January 2008

## Sunday, May 17, 2015

### IIT JEE Main Chemistry Ch 1. THE CONCEPTS - Core Points for Review

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.

JEE Main Syllabus

Contents of Chapter 1 of Jauhar

1.1 Importance of Studying Chemistry
1.2 Physical quantities and their S.I. Units
1.3 Dimensional Analysis
1.4 Measurement and Significant Figures
1.5 Chemical Classification of Matter
1.6 Laws of Chemical Combination
1.7 Dalton Atomic Theory
1.9 Atoms and Molecules
1.10 Atomic and Molecular Mass
1.11 Mole Concept
1.12 Mass-Mole Conversions
1.13 Percentage Composition and Molecular Formula
1.14 Stoichiometry of Chemical Equations
1.15 Stoichiometric Calculations
1.16 Limiting Reactant
1.17 Solution Stoichiometry
1.18 Stoichiometry of of Reactions in Solutions

## 1.1 Importance of Studying Chemistry

Chemistry is the study of the materials that make uup the universe and the changes which these materials undergo. In chemistry, we study the composition of materials to find out what they are made of.  Now we come to know that all the matter in the universe is made up of various elements, compounds and mixtures. Each element has tiny smallest particles called atoms and elements have their stable combination of atoms called molecules. Compounds are made up of molecules which in turn have various atoms of elements.

There are 112 elements.

Elements and compounds when mixed in appropriate conditions undergo changes and new compounds and materials get formed. There changes in the language of chemistry are called chemical reactions.

Chemistry as a subject has helped in providing creating more food, health care products and other necessities of life. It also provided various materials that provide us comforts, pleasure and luxuries. It provided us building materials and synthetic fibres. In recent, new materials such super-conducting ceramics, conducting polymers, optical fibres, microalloys, nanomaterials like carbon fibres were developed by chemistry scholars and scientists.  Chemists are presently study chemical processes related to environmental damage by man made substances and bio-chemical processes to cure old age related diseases and malfunctions of the human body.

1.2 Physical quantities and their S.I. Units

SI (Systeme Internationale) units were adopted by General Conference of Weights and Measures in 1960. The SI system has seven basic units from which all other units are derived.

1.3 Dimensional Analysis

To convert one set of units say metres into another set of units say centimetres, conversion factor method is used. It is also called dimensional analysis.

Unit conversion factors are used in factor conversion method.

We know 1 m = 100 cm

So  1 = 100 cm/ 1 m  and this is called unit conversion factor between cm and m.

We can convert 25 metres into centimetres by writing 25 m (100 cm /1m) which will give 2500 cm. The metres dimension cancels out and cm dimension has come. So apart from numerical terms, dimensions are also multiplied or divided to get the required dimensions.

### 4. Measurement and significant figures

Accuracy
Accuracy is a measure of the difference between the true value (the value to be measured) and the value measured by an instrument.

Accuracy  = Mean of measurements - true value

Precision is depends totally on the instrument and it is the difference between measurements of the same dimension made number of times. It is expressed as the difference between one measurement and the arithmetic mean of the number of measurements.

Actual measurement value - mean of measurements

It can be understood as the lowest measurement - mean of measurements or highest measurement - mean of measurements

Significant figures: Significant figures in a number are include all the certain digits plus one doubtful digit.

If a number has 4 significant figures or digits, it means 3 of them are certain and fourth one is doubtful.

Rules for determining the number of significant figures

1. All non-zero digits are significant
Decimal place does not determine the number of significant figures.

2. A zero becomes significant in case it comes between two non-zero numbers.
3. The zeros at the beginning of a number are not significant.
For example 0.0004 has only one significant figure.
4. All zeros placed to right of a number are significant. They represent the precision of the measuring scale.
For example 267.000 has six significant figures.
(The precision does not come by writing the number. It comes because the instrument has the ability to read a number certainly up to that level of measurement.)

Rules of calculations involving significant figures
Rule 1. The final result of addition or subtraction should be reported up to the same number of decimal places as are present in the term having the least number of decimal places.
6.414
2.3
0.501
------
9.215  answer but the answer should be reported up to one decimal place only as 2.3 is the term having least number of decimal places.

Rule 2. In multiplication or division, the final result should be reported up to the same number of significant figures as are present in the term with the least number of significant figures.
Example: 4.2345*1.25 = 5.293125
The final result should be reported up to three significant figures only as 1.25 has three significant figures. Hence the correct answer to be reported is 5.29.

Rounding off figures of retention of significant figures.

i) If the digit coming after the desired number of significant figures happens to be more than 5, the preceding digit or figure is increased by 1.
ii) If that digit is less than 5, it is neglected and hence the preceding significant figure remains unchanged.
iii) If that digit happens to be 5, the preceding digit is increased by one in case it is odd number. If preceding digit is an even number, it remains the same.

If the problem has number of steps, the rounding off is to be done at the final answer level only.

### 5. Chemical classification of matter

1. Element
Further classification: Metals, non-metals, metalloids
2. Compound
Further classification: Inorganic and organic
3. Mixture
Further classification: Homogeneous mixtures - they are called solutions.
Heterogeneous mixtures: They have visible boundaries of separation between the different constituents and they can be easily seen with naked eye.

### 6. Laws of chemical combination

a. Law of conservation of mass
During any physical o chemical change, the total mass of the products is equal to the total mass of reactants.

b. Law of constant proportions

A pure chemical compound always contains same elements combined together in the same definite proportion by weight.
c. Law of multiple proportions

When two elements combine to form two or more than two compounds, the weights of one of the elements which combine with a fixed weight of the other, bear a simple whole number ratio.

d. Law of reciprocal proportions
When two different elements combine separately with the same weight of a third element, the ratio in which they do so will be the same or some simple multiple of the ratio in which they combine with each other.

e. Gay Lussac’s law of combing volumes
Under similar conditions of temperature and pressure, whenever gases react together, the volumes of the reacting gases as well as products (if gases) bear a simple whole number ratio.

7. Dalton’s atomic theory

To provide theoretical justification to the laws of chemical combination which are experimentally verified, John Dalton postulated a simple theory of matter. The basic postulates of Dalton’s atomic theory are:

a. Matter is made up of extremely small indivisible and indestructible ultimate particles called atoms.
b. Atoms the same element are identical in all respects ie., in shape, size, mass and chemical properties.
c. Atoms of different elements are different in all respects and have different masses and chemical properties.
d. Atom is the smallest unit that takes part in chemical combinations.
d. Atoms of two or more elements combine in a simpler whole number ratio to form compound atoms (molecules).
e. Atoms can neither be created nor destroyed during any physical or chemical change.
f. Chemical reactions involve only combinations, separation or rearrangement of atoms.

Modern atomic theory
As a result of new discoveries made after Dalton developed his postulates, some modifications were done to atomic theory. They are:

1. Atom is no longer considered to be indivisible: It is found that atom is made up of subatomic particles such as electrons, protons and neutrons. We now state how many electrons are there, protons are there in an atom.

2. Atoms of same element may not be similar in all respects. Atoms of same elements have different atomic masses. These different atoms are called isotopes.

3. Atoms of different elements may have similar one or more properties. Atomic mass of calcium and argon (40 a.m.u.) are same. So the property of atomic mass is same for atoms of different elements. Isobars or elements or atoms having the same atomic mass.

4. Atom is the smallest unit which takes part in chemical reactions. Though electrons and protons are there, it is atom which takes part in chemical reactions and electrons exchange takes place between atoms.

5. The ratio in which the different atoms combine may be fixed and integral but may not always be simple. For example in sugar molecule the ratio of C,H and O atoms is 12:22:11, which is not simple.

6. Atom of one elements may be changed into atoms of other element. Transmutation is the process by which atoms one element can be changed inot elements of other elements by subjecting it to alpha rays.

7. The mass of atom can changed into energy. Mass and energy are inconvertible. The equation give for such conversion is E = mc². Hence we cannot say that mass is not destructible. But in chemical reactions, atom remains unchanged and its mass is not destroyed to liberate energy.

Avogadro's hypothesis or suggestion is that matter consists of two kinds of ultimate particles. These are atoms and molecules.

Atoms are the smallest particle of an element which may or may not have independent existence, but it takes part in chemical reactions.

Molecule is the smallest particle of a substance (element or compound) capable of independent existence.

The actual hypothesis is that under similar conditions of temperature and pressure, equal volumes of all gases contain equal number of molecules.

## 1.9 Atoms and Molecules

Atoms are the smallest particle of an element which may or may not have independent existence, but it takes part in chemical reactions.

Molecule is the smallest particle of a substance (element or compound) capable of independent existence.

There are 112 elements in nature as per the present knowledge. Obviously there are 112 different types of atoms.

Molecules may have two or more atoms. Molecules are divided into two types:

1. Homoatomic molecules

2. Heteroatomic molecules

## 1.10 Atomic and Molecular Mass

Atomic Mass: An atom is such a small particle that its mass cannot be determined with the help of any available balance.  By an indirect method, the absolute mass of hydrogen atom has been found to be 1.66 X 10 to the power of -24 g.

Chemists have defined the atomic mass of hydrogen as one and expressed the atomic mass of other elements as multiples of hydrogen's atomic mass. The relative atomic masses expressed in terms of hydrogen as termed atomic weights.

Atomic weights of some common elements

Metals

Magnesium  24.3
Aluminium  27.0
Iron              55.8
Zinc             65.4
Tin             118.7

Gram Atomic Mass: Gram atomic mass is the quantity of an element whose mass in grams is numerically equal to its atomic mass.

Molecular Mass: Measuring the mass of a single molecule is not possible. Hence as in the case of atoms,  molecular mass is defined as the average relative mass of its molecule as compared to the mass of an atom of carbon (C12) having mass number 12.

### 11. Mole concept

A mole is measuring unit like for example dozen.
A mole is a collection of 6.022*1023 particles

## 1.12 Mass-Mole Conversions

The mass of 6.022 X 10 to the power 23 molecules of a substance is equal to its gram moleculuar mass or gram molecule.

Ionic compound have the formula of composition of ions in the compound.  In their case the mass of one mole of formula units in grams is equal to  formula mass expressed in grams or gram formula mass of the compound. Thus, mass of 6.022 X 10 to the power 23 formula units (or one mole formula units) of any ionic substance in gram is equal to its gram formula mass.

Molar Mass: The mass of 1 mol of a substance is called its molar mass (M). The units of molar mass are g mol to the power -1 or kg mol to the power -1.

Mole in Terms of Volume

It has been observed that one mole (6.022 X 10 to the power 23 molecules) of an ideal gas occupies 22.4 litres at N.T.P. (0 degrees C and 1 atm pressure)

## 1.13 Percentage Composition and Molecular Formula

Molecular formula is also the chemical formula of a compound. It gives the representation of a molecule of a substance in terms of symbols of various elements present in it. The determiination of chemical formula requires chemical analysis to determine:

1. the elements present in it.
2. the relative of each element in the given mass of the compound.

Percentage Composition
The composition is generally expressed as the mass percentage composition. It gives the mass of each element expressed as the percentage of the total mass of the compound. It can also be expressed as the number of grams of the element present in 100 g of the compound.

Empirical Formula and Molecular Formula

Empirical formula gives the elements present in a compound.
Molecular formula gives the number of atoms of each element present in the compound. This is ascertained from the percentage composition calculations.

## Stoichiometry

1.14 Stoichiometry of Chemical Equations
1.15 Stoichiometric Calculations
1.16 Limiting Reactant
1.17 Solution Stoichiometry
1.18 Stoichiometry of of Reactions in Solutions

## 1.14 Stoichiometry of Chemical Equations

Stoichiometry is derived from the Greek words stoicheion meaning elementand metron meaning measure.

It means measuring elements in chemical compounds. In chemical reactions, it is measuring reactants and products.

Stochiometric coefficients or numbers: The numbers which appear before the chemical symbols in a chemical equation.

Chemical equation gives information about moles of various reactants and products. Hence molar masses involved in the reaction and molar masses of products.

Balancing of Chemical Equations

1. Trial and error method
2. Partial equation method
3. Oxidation Number method
4. Ion-electron method

## 1.15 Stoichiometric Calculations

In stoichiometric calculations we find to mole to mole relationships in chemical equations. Mass to mass relationships are also calculated. Mass, volume relationships are calculated. Volume - volume relationships are calculated. You can imagine each of them based on the discussion we made above regarding mole concept, molecular mass, and mole volume.

## 1.16 Limiting Reactant

If reactants of different masses are mixed in a reaction vessel, the reactant that is completely consumed when a reaction goes to completion is called the limiting reactant of that mixture of reactants.  The other reactants present are called excess reagents. We need to minimize the excess reagents as it is a waste and we may not be able use them in other reactions due to their contamination in various ways because of using them in this reaction.

## 1.17 Solution stoichiometry

In solution generally one component is present in lesser amount and it is called solute.

The other present in excess is called the solvent.

The amount of solute present in a given quantity of solvent or solution is expressed in terms of concentration.

Molarity = Amount of a substance (in mol)/Volume of solution expressed in dm^3
It is applicable to solutions only.

The unit of molarity is mol dm^-3. It is commonly abbreviated by the symbol M and is spelled as molar.

Molality = Amount of a a substance (in mol)/Mass of solvent expressed in kg
It is also applicable to solutions only

Mass percentage of substance in a system

Mole fraction of a substance in a system

CONCEPT OF EQUIVALENT
__________________________

"One equivalent of a substance in a reaction is defined as the amount of substance which reacts or liberates 1 mol of electrons (or H^+ or OH^- ions).

## 1.18 Stochiometry of reactions in solutions

Many reactions are carried out in aqueous solutions. In this case their concentration is important measure. The amounts of the products of a reaction can be calculated from the volumes of the solutions of the reactants and their concentrations. In the book, the calculations are illustrated through examples.

Updated  17 May, 16 May 2015

Last updated 19 Jan 2008, 30 Nov 2014

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