Chemistry

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Chemistry

As far as Jee is concerned I believe that Chemistry plays a really important role. For all those aspirants who are worried about their results in JEE as they are having trouble in Chemistry, I have a word of help for them which can change your scores in chemistry in JEE. First of all, you have to have the full syllabus of Chemistry with you and then you should see the chapters in which you are having most trouble and then mark them three stars then two and then one. By this, you will have a well-structured list with you that will give you the direction of flow of your hard work. Then for the three stared topics, give them a full day and study the concepts with full concentration and if you are having trouble with the parts of inorganic chemistry then I believe you have to read the topics on daily basis for more than 1 hrs. As inorganic chemistry demands the contiunous revision of the facts and it has very less to do with the understanding of concepts.  If you are having a problem with physical chemistry, you will have to solve lots of questions of different types and look for the solved examples for help rather than reading the concepts again and again.

I believe this interaction will be helpful for your Jee.

Carbon and its Compounds

1. Oxidation Reaction:

When Ethanol that is (C2H5OH) is treated with acidified Potassium Dichromate (K2Cr2O7) or alkaline Potassium Permanganate (KMN04) then it is converted into Ethanoic Acid (CH3COOH). Now as you can see that oxygen molecule in Ethanoic Acid is more than Ethanol so clearly there is oxidation and K2CR2O7 and KMnO4 are just acting as an oxidizing agent.

 2. Addition Reaction:
It is the most easy reaction as there is no use of compounds with long carbon chains and all. All you need to remember is the names of all saturated and unsaturated hydrocarbons till C6.
Now here, when unsaturated hydrocarbons are treated with hydrogen in presence of Nickle or Palladium catalyst then they convert into saturated hydrocarbons. For example:
C2H4 when reacted with hydrogen in presence of Nickel then it converts into C2H6. Here, Nickel is just a catalyst. It is not at all taking part in reaction. It is a very useful reaction in Cooking Oil manufacturing industries. As it is adding hydrogen to the compound, so it is also called Hydrogenation process.
For your reference, you can refer this part from NCERT book as it will be best for exam point of view.

3. Substitution Reaction:
When saturated hydrocarbons are treated with Chlorine in presence of sunlight then Chlorine displaces Hydrogen from its compound and forms a compound with hydrocarbon. Also HCl is produced as by-product.
For example, if C2H6 is treated with Chlorine, then C2H5Cl and HCl is formed.
Again if C2H5Cl is treated with Chlorine then it will become C2H4Cl2 is produced. This will go on until Hydrogen is completely displaced.

Some Important Carbon Compounds

Alcohols : Compounds containing -OH group attached to a carbon atom are known as alcohols.

Example : Ethanol (C₂H₅OH) : commonly known as alcohol.

Properties of ethanol :

1. Reaction with sodium : Due to its weakly acidic nature, ethanol reacts with sodium to librate H₂ gas.

2. Reaction with conc : H₂SO₄ :

Alcohol as a fuel : Alcohol (ethanol) is added to petrol upto 20% and the mixture is called “gasol”.

Harmful Effects of Drinking Alcohol :

If the alcohol used for drinking purposes contains some methyl alcohol (CH₃OH) as impurity then it may cause serious poisoning and loss of eye sight.

It is habit forming and damages liver if taken regularly in large quantities.

Ethanoic Acid (Acetic Acid) CH₃COOH:

Ethanoic acid, commercially known as acetic acid belongs to a group of acids called carboxylic acid.

Chemical properties :

(i) Reaction with a base :

2CH₃COOH + 2NaOH → 2CH₃COONaH₂O

(ii) Reaction with carbonates and bicarbonates :

2CH₃COOH + Na₂CO₃ → 2CH₃COONa + CO₂ + H₂O

CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂

(iii) Reaction with alcohol : (Esterification)

Esters react is the presence of an acid or a. base to give back the alcohol and carboxylic acid-this reaction is known as saponification.

14. Soaps and Detergents :

Soaps : Soaps are sodium or potassium salts of long chain acid carboxylic acids.

Detergent : They are ammonium or sulphurate salts of long chain carboxylic acids.

Periodic Classification of Elements

I think we you all must be knowing about periodic table and functions. But in this chapter we will be learning about the history of its formation.

Since early 1900's many efforts were taken in the formation of periodic table. The first one was taken by Johann Wolfgang Drobenier. He arranged few ele