Updated two posts in carboxylic acid revision points
http://iit-jee-chemistry.blogspot.com/2008/02/carboxylic-acids-introduction.html
http://iit-jee-chemistry.blogspot.com/2008/02/methods-of-preparation-of.html
Updated one more post in carboxylic acid revision posts on 31-3.2008 (4.55 p.m.IST)
http://iit-jee-chemistry.blogspot.com/2008/02/carboxylic-acids-characteristic.html
Saturday, March 29, 2008
Tuesday, March 4, 2008
IIT JEE Chemistry
As I have read all the chapters of chemistry and did some posts in study notes as well as revision points, I shifted my attention to physics to do a similar job. I am presently reading thermal physics and going through past objective questions and shall post formulas and concepts for revision in
www.iit-jee-physics.blogspot.com
I plan to complete the study of full Physics by May 2008 and then take up Mathematics.
Recent update on Chemistry blog(6-3-2008)
Carboxylic acids - Characteristic reactions-revision points
http://iit-jee-chemistry.blogspot.com/2008/02/carboxylic-acids-characteristic.html
www.iit-jee-physics.blogspot.com
I plan to complete the study of full Physics by May 2008 and then take up Mathematics.
Recent update on Chemistry blog(6-3-2008)
Carboxylic acids - Characteristic reactions-revision points
http://iit-jee-chemistry.blogspot.com/2008/02/carboxylic-acids-characteristic.html
Wednesday, February 20, 2008
Glossary - Surface Chemistry - for IIT JEE
Adsorption
The term adsorption implies the presence of excess concentration of any particular component in one of the three phases of matter (known as adsorbate) at the surface of liquid or solid phase (known as adsorbent) as compared to that present in the bulk of the material.
Colloids
Colloids or sols are the substances whose sizes lie in between the solutes present in a true solution (e.g., salt, sugar) and the solutes present in suspension (e.g., sand).
The diameters of colloidal particles may range from 1 to 100 nm. The particles in colloidal state do not settle down on standing, are not visible and they can pass through a filter paper. However, they do not pass through a perchment paper or animal membrane.
Emulsion
Emulsion is a liquid dispersed in a liquid.
The term adsorption implies the presence of excess concentration of any particular component in one of the three phases of matter (known as adsorbate) at the surface of liquid or solid phase (known as adsorbent) as compared to that present in the bulk of the material.
Colloids
Colloids or sols are the substances whose sizes lie in between the solutes present in a true solution (e.g., salt, sugar) and the solutes present in suspension (e.g., sand).
The diameters of colloidal particles may range from 1 to 100 nm. The particles in colloidal state do not settle down on standing, are not visible and they can pass through a filter paper. However, they do not pass through a perchment paper or animal membrane.
Emulsion
Emulsion is a liquid dispersed in a liquid.
Glossary - Isomerism - for IIT JEE
Isomerism
The existence of two or more compounds with same molecular formula but different properties (physical, chemical or both) is known as isomerism; and the compounds themselves are called isomers.
Isomerism types:
i) Chain, nuclear or skeleton isomerism
This type of isomerism is due to the difference in the nature of the carbon chain (i.e. straight or branched) which forms the nucleus of the molecule,
ii) Position isomerism
It is due to the difference in the position of the substituent atom or group or an unsaturated linkage in the same carbon chain.
iii) Functional isomerism
This type of isomerism is due to difference in the nature of functional group present in the isomers,
iv) Metamerism
It is due to the difference in nature of alkyl groups attached to the same functional group. This type of isomerism is shown by compounds of the same homologous series.
v) Tautomerism
Tautomerism may be defined as the phenomenon in which a single compound exists in two readily interconvertible structures that differ markedly in the relative position of at least one atomic nucleus, generally hydrogen. The two different structures are known as tautomers of each other.
Stereo isomerism
When isomers have the same structural formula but differ in relative arrangement of atoms or groups in space within the molecule, these are known as stereoisomers and the phenomenon as stereoisomerism. The spatial arrangement of atoms or groups is also referred to as configuration of the molecule and thus we can say that the stereoisomers have the same structural formula but different configuration. Stereoisomerism is of two types.
(i) Geometrical isomerism
The isomers which possess the same structural formula but differ in the spatial arrangement of the groups around the double bond are known as geometrical isomers and the phenomenon is known as geometrical isomerism.
ii) Optical isomerism
This type of isomerism arises from different arrangements of atoms or groups in three dimensional space resulting in two isomers which are mirror image of each other. Optical isomers contain an asymmetric (chiral) carbon atom ( a carbon atom attached to four different atoms or groups) in their molecules.
The existence of two or more compounds with same molecular formula but different properties (physical, chemical or both) is known as isomerism; and the compounds themselves are called isomers.
Isomerism types:
i) Chain, nuclear or skeleton isomerism
This type of isomerism is due to the difference in the nature of the carbon chain (i.e. straight or branched) which forms the nucleus of the molecule,
ii) Position isomerism
It is due to the difference in the position of the substituent atom or group or an unsaturated linkage in the same carbon chain.
iii) Functional isomerism
This type of isomerism is due to difference in the nature of functional group present in the isomers,
iv) Metamerism
It is due to the difference in nature of alkyl groups attached to the same functional group. This type of isomerism is shown by compounds of the same homologous series.
v) Tautomerism
Tautomerism may be defined as the phenomenon in which a single compound exists in two readily interconvertible structures that differ markedly in the relative position of at least one atomic nucleus, generally hydrogen. The two different structures are known as tautomers of each other.
Stereo isomerism
When isomers have the same structural formula but differ in relative arrangement of atoms or groups in space within the molecule, these are known as stereoisomers and the phenomenon as stereoisomerism. The spatial arrangement of atoms or groups is also referred to as configuration of the molecule and thus we can say that the stereoisomers have the same structural formula but different configuration. Stereoisomerism is of two types.
(i) Geometrical isomerism
The isomers which possess the same structural formula but differ in the spatial arrangement of the groups around the double bond are known as geometrical isomers and the phenomenon is known as geometrical isomerism.
ii) Optical isomerism
This type of isomerism arises from different arrangements of atoms or groups in three dimensional space resulting in two isomers which are mirror image of each other. Optical isomers contain an asymmetric (chiral) carbon atom ( a carbon atom attached to four different atoms or groups) in their molecules.
Glossary - Inductance - Resonance - for IIT JEE
Hyperconjugation
When a H-C bond is attached to a double or triple bond in an unsaturated hydrocarbon, the sigma electrons of the H-C bond interact or enter into conjugation with the unsaturated system.
The interactions with between electrons of π systems (multiple bonds) and the adjacent sigma bonds (single H-C bonds) of the substituent groups in organic compounds is called hyperconjugation.
According to this concept, if an alkyl group carrying at least one hydrogen atom is attached to a unsaturated carbon atom, it releases electrons of carbon-hydrogen single bond towards the multiple bonds.
Hyperconjugation effect is similar to resonance effect.
When a H-C bond is attached to a double or triple bond in an unsaturated hydrocarbon, the sigma electrons of the H-C bond interact or enter into conjugation with the unsaturated system.
The interactions with between electrons of π systems (multiple bonds) and the adjacent sigma bonds (single H-C bonds) of the substituent groups in organic compounds is called hyperconjugation.
According to this concept, if an alkyl group carrying at least one hydrogen atom is attached to a unsaturated carbon atom, it releases electrons of carbon-hydrogen single bond towards the multiple bonds.
Hyperconjugation effect is similar to resonance effect.
Glossary - Alkyl and Aryl Halides for IIT JEE
Allylic, Akyl, arylic, benzylic and vinylic carbon, Hydrogen, halide
allylic carbon: a carbon adjacent to a C=C double bond
allylic hydrogen: a hydrogen on an allylic carbon
an allylic C-H bond is weaker than a vinylic C-H bond
Alkyl halide: a compound containing a halogen atom covalently bonded to an sp3 hybridized carbon atom.
Given the symbol R-X
If it is bonded to a benzene ring, it is called an aryl halide, given the symbol Ar-X
carbon next to a benzene ring is called benzylic carbon and the hydrogens on benzylic carbon are called benzylic hydrogens
If the halogen is bonded to an sp² hybridized carbon, it is a called a vinylic halide
Allylic and benzylic positions are more reactive than other positions in free radical halogenations
allylic carbon: a carbon adjacent to a C=C double bond
allylic hydrogen: a hydrogen on an allylic carbon
an allylic C-H bond is weaker than a vinylic C-H bond
Alkyl halide: a compound containing a halogen atom covalently bonded to an sp3 hybridized carbon atom.
Given the symbol R-X
If it is bonded to a benzene ring, it is called an aryl halide, given the symbol Ar-X
carbon next to a benzene ring is called benzylic carbon and the hydrogens on benzylic carbon are called benzylic hydrogens
If the halogen is bonded to an sp² hybridized carbon, it is a called a vinylic halide
Allylic and benzylic positions are more reactive than other positions in free radical halogenations
Glossary - Aldehydes and Ketones - for IIT JEE
Aldehydes
Aldehydes contain carbonyl group C=O as functional group and the carbonyl atom carries at least one H atom.
Cannizzaro reaction
Aldehydes which do not have α-hydrogen atom react with concentrated sodium hydroxide (NaOH) or potassium hydroxide (KOH) in such a way that one molecule get oxidized to acid and the second molecule gets reduced to alcohol.
Note two molecules of aldehyde participates in the reaction.
This self oxidation-reduction under the influence of a base is known as the Cannizzaro's reaction.
Ketones
In ketones, also carbonyl group C=O is the functional group. But the carbonyl carbon does not contain any H atoms, but it is attached to two alkyl or aryl groups.
Cannizzaro reaction
Aldehydes which do not have α-hydrogen atom react with concentrated sodium hydroxide (NaOH) or potassium hydroxide (KOH) in such a way that one molecule get oxidized to acid and the second molecule gets reduced to alcohol.
Note two molecules of aldehyde participates in the reaction.
This self oxidation-reduction under the influence of a base is known as the Cannizzaro's reaction.
Aldehydes contain carbonyl group C=O as functional group and the carbonyl atom carries at least one H atom.
Cannizzaro reaction
Aldehydes which do not have α-hydrogen atom react with concentrated sodium hydroxide (NaOH) or potassium hydroxide (KOH) in such a way that one molecule get oxidized to acid and the second molecule gets reduced to alcohol.
Note two molecules of aldehyde participates in the reaction.
This self oxidation-reduction under the influence of a base is known as the Cannizzaro's reaction.
Ketones
In ketones, also carbonyl group C=O is the functional group. But the carbonyl carbon does not contain any H atoms, but it is attached to two alkyl or aryl groups.
Cannizzaro reaction
Aldehydes which do not have α-hydrogen atom react with concentrated sodium hydroxide (NaOH) or potassium hydroxide (KOH) in such a way that one molecule get oxidized to acid and the second molecule gets reduced to alcohol.
Note two molecules of aldehyde participates in the reaction.
This self oxidation-reduction under the influence of a base is known as the Cannizzaro's reaction.
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