Sunday, September 30, 2012

IIT JEE Chemistry Concepts Revision Materials

IIT JEE Chemistry Concepts Revision Materials

IIT JEE Chemistry Concepts Revision Materials

Revision points in various chapters of chemistry at 11 and 12 standards (Classes) and especially for IIT JEE.
Revision points for revision at the end of study of a chapter as well as for periodic and final revisions. These revision points will be scheduled as a plan for revision for JEE 2010 and JEE 2011 during (January 2010 to April 2010)
Detailed topicwise revision points 
    JEE Revision - Hund's rule     
    Revision - Hess's law   

Saturday, July 21, 2012

Stereochemistry - Introduction

Stereochemistry is the study of the orientation in space of the atoms of a molecule.  There are molecules with the same molecular formula and structure but with different orientations of atoms in space. There are significant number cases, in which it happens.

It is found that there are molecules, in which we find  two different  molecules are mirror-images of each other, but they will not super-impose and remain as two separate chemical entities.  They are known as enantiomers.

The physical and chemical properties of the enantiomers are the same in a symmetrical environment, but differ if there is asymmetry in the environment (e.g. a biological system).  Enantiomers also differ in the direction that they rotate plane-polarized light.  Both enantiomers will rotate the plane of the light to the same extent, but in opposite directions.  Such molecules are said to be optically active.

Concepts in Stereochemistry

Enantiomers: "A species with a non-superimposable mirror image."  An example of a pair of enantiomers is lactic acid.

Racemic mixture, or racemate: A racemic mixture, or racemate is a mixture of exactly equal quantities of both enantiomers, so that it does not rotate plane-polarized light in either direction (as the effects of both enantiomers cancel out.)

More information

Chemistry Knowledge History - March

Chemistry Knowledge History - May

Chemistry Knowledge History - June

Friday, July 13, 2012

Chemistry Knowledge History - August

Chemsitry History

Chemistry Knowledge History - September

Chemsitry History

Chemistry Knowledge History - October

Chemsitry History

Monday, April 30, 2012

IIT JEE Revision for 2010 - Questions/Problems for Final Revision

IIT JEE Revision for 2010 - Questions/Problems for Final Revision

IIT JEE Revision for 2010 - Questions/Problems for Final Revision

Questions and Problems for Final Revision for IIT JEE 2010 in Chemistry, Mathematics and Physics

The schedule provided for study for IIT JEE 2010 calls for completion of the full course by 31 December 2009 and it also requires that all problems given in the text books are completed by that date. The problems of the last chapters may spill over into January.
The revision problems sets now indicated are expected to help you to recollect concepts, formulas and their application at random. Each set of each subject will have five questions. You can think of one question every hour (three subjects - 15 questions). Many of these questions are taken from past JEE questions. Therefore, you are attempting JEE level questions. The JEE questions also help me in selecting similar standard questions from other sources. If you find any difficulty in the language of questions, don't waste your time. Simply ignore the question. This is not the time to waste. Anyway you are going to have lot of work to do given by your coaching institutes. These question sets are an extra support to you. Don't waste your time for any shortcomings in them.
All the question sets on blogs maintained on blogger platform.


Revision set 16, Revision set 17, Revision set 18, Revision set 19, Revision set 20 



IIT JEE Revision - Organic Chemistry - Some Special Reactions

IIT JEE Revision - Organic Chemistry - Some Special Reactions

IIT JEE Revision - Organic Chemistry - Some Special Reactions

Special reactions named after persons (mainly)


Kolbe's reaction
Aromatics or Arenes
Wurtz-Fittig reaction
Friedel-Craft alkylation reaction
Friedel-Craft acylation reaction

Aldehydes - Ketones

Bouven Blac reaction
Claisen condensation
Hoffman bromamide or degradation reaction
Baker-Mulliken's test
Hoffman's method
Gabriel's phthalimide synthesis
Mendius reaction
Sabatier and Mailhe method
Hofmann's elimination reaction
Hofmann mustard oil raction
Libermann's ntroso reaction
Schotten Baumann reaction
Hinsberg's method for separation of amines
Hofmann method for separation of amines
Cyanides and Isocyanides
Sandmeyer's reaction
Diazonium salts
Sandmeyer's reaction
Gattermann reaction
Schiemann reacion

NON-METALS - IIT JEE Syllabus and Material

NON-METALS - IIT JEE Syllabus and Material

NON-METALS - IIT JEE Syllabus and Material

JEE Syllabus

Isolation/preparation and properties of the following non-metals:
sulphur and

Properties of allotropes of
carbon (only diamond and graphite),
phosphorus and


Compounds relevant to study of Boron

Borax (Na two B four O seven) Calamnite (Ca two B six O eleven)
Boron Trioxide (B two O three) Boric Acid (H three B O three)
Boron Nitride (B N)

Sodium Carbonate (Na two C O three)

Boron (B) - Preparation and Properties

atomic number electronic configuration

Z = 5, 1s²2s²2px¹

Main Ores of Boron

Borax, Kernite, Colemanite and Orthoboric acid.

Methods of Obtaining Boron

1. By the reduction of boric oxide y an electropositive metal like magnesium.
2. By the reductin of volatile boron compounds by dihydrogen at high temperatures (1270K).
3. By the electrolytic reduction of fused borates or other boron compounds (e.g., KBF-4, potasium tetrafluoroborate) in molten KCL/KF at 1073K.
4. By the thermal decomposition of boron tri-iodided over red hot tungsten.
5. By thermal decomposition of boron hydrides and boron halides at about 1173K.

Physical Properties of Boron

1. Boron is an extremely hard solid next to diamond.
2. Its melting point is 2450K and boiling point is 3925K.
3. It is a poor conductor of heat electricity.
4. It has two isotopic forms - B-10 and B-11. Relative abundance 19% and 81% respectively.

Chemical Properties of Boron

1. Combination with nonmetals: At room temperature, it reacts with flourine. Superficial reaction with oxygen. At higher termperatures, it reacts directly with all nonmetals except H, Ge, Te and nobles gases.
2. With water: It does not react with water even in the form of steam.
3. Acids: HCL does not react with boron.
When heated with concentrated sulphuric acid or nitric acid, boron is oxidized to boric acid.
Boron does not react with nonoxidizing acids.
4. Boron react with fused caustic alkalies like NaOH and KOH forming borates.
It dissolves in fused Na-2CO-3 and NaNO-3 mixture at 1173K.
5. Boron comines directly with almost all metals (except heavy metals) at higher temperatures.
Heavy Metals not combining with boron include Ag, Au, Cd, Hg, Ga, In, Tl, Pb, Sn, Bi etc.

Boron belongs to 13th group.
It has a very high melting point(2453 K).

It is extracted from minerals Borax(Na-2 B-4 O-7) or Calamnite (Ca-2 B-6 O-11)

Process of extracting Boron from Borax:
i) Borax is treated with concentrated hydrochloric acid. Boric acid is precipitated.
ii) boric acid is strongly heated. Boron trioxide is obtained (B-2 O-3).
iii) Boron trioxide is heated with Na, K or Mg pieces. Amorphous form of boron is obtained.

Alternatively mixture of boron tribromide vapours and hydrogen are passed over electrically heated filament of tungsten at 1200 degree centigrade. Crystalline form of Boron is obtained.

In another way, Boron trioxide can react with Aluminium to give Boron.
Silicon (Si)

Compounds relevant to study of silicon

Silica (Si O two)
Silicon Halide (Si X four) X is for halogen

silicon (Si) - Preparation and Properties

Electronic configuration of Silicon

Atomic Number is 14. 1s²2s²2p63s²3p²

Methods of obtaining Silicon

1. Heating finely divided silica with magnesium powder.
2. Heating potassium silicoflouride with potassium metal.
3. Heating potassium silicoflouride wtih Al or Zn in an iron crucible.
4. Passing a current of SiCl-4 over molten aluminium.

Physical Properties of Silicon

Silicon is available in two allotropic forms. the amorphous silicon and the crystalline or admantine silicon.

Amorphous silicon is a dark brown powder which is insoluble in water.
Crystalline silicon forms pale yellow crystals.

Chemical properties of silicon

1. Silicon burns in air or oxygen forming silicon dioxide.
2. With halogens, it forms halides, SiX-4.
3. With fused acqueous caustic alkalies, silicon forms alkali silicates with liberation of hydrogen.
4. Silicon decomposes on red heating liberating hydrogen.
5. Metals like Magnesium and nonmetal carbon form silicides with silicon.
Sulphur (S)

Compound relevant to study of Sulphur

Hydrogen Sulphide (H two S)
Sulphur Dioxide (S O two)
Sodium Thio-Sulphate (Na two S two O three)

Ions formed by Sulphur

Sulphide ion (S O three (two-))
Thiosulphate ion (S two O three (two-))

Sulphur occurs in the native as well as combined form.Large quantites of sulphur are obtained from underground deposits in USA.

Partial combustion of Hydrogen sulphide produces sulphur.
Reaction of Hydrogen Sulphide with Sulphur dioxide also gives sulphur.
Sulphur occurs as S eight. It is a puckered ring with crown conformation.

Several allotropic forms of sulphur are available.

Rhombic sulphur (or alpha sulphur) is the stablest form. It is obtained by evaporation of solution of sulphur in carbon disulphide.

At about 95 C - 96 C rhombic sulphur is changed into another allotropic form monoclinic sulphur (als known as prismatic or beta sulphur).
Monoclinic sulphure has needle shaped crystals.

Other allotropic forms are amorphous (or colloidal) and plastic sulphur (or Gamma sulphur).

Amorphous sulphur is obtained by (1) the action of dilute Hydrochloric acid on sodium thio sulphate solution, and
(2)by passing Hydrogen sulphide through dilute nitric acid.

Plastic sulphur is obtained by pouring boiling sulphur in cold water. This results in rapid cooling. Plastic sulphur consists of a completely random arrangement of chains of sulphur atoms. On standing it passes over to the crystalline rhombic sulphur.

Sulphur is also active element like Oxygen. It combines with a large number of metals and nonmetals.

Sulphur is oxidized by concentrated nitric acid and sulphuric acid.
It also reacts with hot concentrated solution of alkalies.



Allotropes of Carbon

Carbon has two allotropic forms - diamond and graphite. Other amorphous carbons are actually micro crystals of graphite.

Diamond, an allotrope of Carbon is face centered crystal. It is the hardest natural substance. It is a nonconductor of electricity. It has high refractive inded (2.45) and much of the light that falls on it is internally reflected.

Diamond burns in air at 900 C and in oxygen at 700 C and forms carbon dioxide.

Graphite has a layer like structure in the three dimensional space and this gives it the lubricating property.

The carbon content of various amorphous forms of graphite; Peat (60%), Lignite (70%), Bituminous coal (78%) Semibituminous coal (83%) and Anthracite Coal (90%). The residue that remains after destructive distilation of coal in the absence of air is coke.

• Graphite is a slippery black powder.
• Graphite is the only nonmetallic substance that conducts electricity.
• Each C atom is bonded to 3 other C atoms, forming one double bond and 2 single bonds.
• Every C atom in the graphite structure is bonded in the same way, with each carbon atom having one double bond and 2 single bonds.
• Graphite consists of a two dimensional layer in which C atoms are arranged in a series of regular hexagons.
• There are weak attractions between layers and the layers can readily slide past one another.
• By experiment, it has been determined that the 3 bonds associated with the C atoms are identical. Thus, the fourth pair of electrons is really delocalized. This accounts for the electrical conductivity of graphite.

• Diamond is a colorless crystal.
• Diamond is the hardest naturally occurring substance.
• Each carbon atom is bonded to four other carbon atoms in a tetrahedral arrangement.
• The tetrahedral arrangement of carbon atoms gives diamond its characteristic
physical properties such as:

o diamond is very hard
o diamond has a high melting point
o diamond is not easily compressed
o when given a good cut, diamond reflects light off of its facets.
• Diamond is actually a giant interlocking group of tetrahedrally arranged atoms. The bond angle between any two bonds in the crystal is 109.5o.

Allotropes of Phosphorus

Phosphorus has three main allotropes: white, red and black.

White phosphorus is poisonous and can spontaneously ignite when it comes in contact with air. For this reason, white phosphorus must be stored under water and is usually used to produce phosphorus compounds.

Red phosphorus is formed by heating white phosphorus to 250°C (482°F) or by exposing white phosphorus to sunlight. Red phosphorus is not poisonous and is not as dangerous as white phosphorus, although frictional heating is enough to change it back to white phosphorus. Red phosphorus is used in safety matches, fireworks, smoke bombs and pesticides.

Black phosphorus is also formed by heating white phosphorus, but a mercury catalyst and a seed crystal of black phosphorus are required. Black phosphorus is the least reactive form of phosphorus and has no significant commercial uses.

Allotropes of sulphur

Sulfur exists as a number of different allotropes. Below 95.6°C, the stable crystal form is rhombic, while above this temperature the element changes to a triclinic form. Both these forms contain cyclic S8 molecules. At temperatures just above its melting point, sulfur is a yellow liquid also containing S8 molecules. At about 160°C, the sulfur atoms link together in chains and the liquid becomes dark brown and more viscuous. If the molten sulfur is quickly cooled, for example, by pouring it into cold water, the result is a reddish-brown solid called plastic sulfur. Above 200°C the viscosity decreases.

Sulfur vapor contains a mixture of S2, S4, S6, and S8 molecules. So-called "flowers of sulfur" is a yellow powder obtained by subliming the vapor.

Rhombic sulphur
Yellow transparent crystals
Melt pt. 113 oC
Obtained when sulphur crystallises
from solution.

Monoclinic sulphur
Amber coloured needles
Melt pt. 119 oC
Obtained when sulphur
solidifies above 95.6 oC.

At atmospheric pressure the rhombic form is stable below 95.6 oC and the monoclinic form above this temperature. Only at the transition temperature can the two allotropes exist in equilibrium with each other.

When sulphur is heated it melts and undergoes a series of changes as the temperature rises.



Ozone (O three) is an allotropic form of Oxygen.
It is naturally formed above 20 Km from the earth from oxygen by absorbing sunlight. Ozone layer protects earth from concentration of ultraviolet rays. chlorofluorcarbons (C Cl two F two) used as refrigerant releases active chlorine after absorbing sunlight and this active chlorine decomposes ozone leading to destruction of ozone layer.

Monday, April 2, 2012

Chemistry Videos Knol Book posted in the blog

Knol book migrated from Knol and posted in the Videos for IIT JEE Chemistry blog.

Wednesday, January 25, 2012

Chemistry Lecture Video

Chemistry lecture videos collection is being trasferred from Knol to a blog along with this knol.