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IGCSE CHEMISTRY DOUBTS

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Vin:

--- Quote from: gaurav95 on June 04, 2010, 04:51:27 am ---One more q

do we have cyclic hydrocarbons i guess one q had come abt properties

can somebody give info abt topics related to this..........

--- End quote ---

They are not in our syllabus, from what I know they are just another method of representing hydrocarbons in a circular way < I am NOT sure!

Ivo:
~VIN1094~, for w08, Q7) b) iii), I do not get it at all.  The mark scheme says either 1 or 2-chloropropane is the product of the reaction, and that HCl is not a product.

Please explain, many thanks in advance.

gaurav95:

--- Quote from: ~VIN1094~ on June 04, 2010, 10:46:43 am ---Depends on the q, here its vitamin C. Usually all vitamins contain -OH groups. Only for the structural formula you need to specify -OH and not the molecular formula. ;)


For Q.7 b)iii) There are 'n' number of types of chlorination. This depends on how much chlorine you use and which hydrocarbon you use.

When chlorination occurs it replaces one hydrogen atom from the hydrocarbon and forms HCl

E.g. Chlorination of methane::

    H                                                  H
    |                                                   |  
H- C - H   +    Cl2 ------>  H- C - Cl  +  HCl
    |                                                   |
    H                                                  H

CH4  + Cl2  ----> CH3Cl  +  HCl
Product:: Chloromethane (methyl chloride)
 

Similarly,
CH3Cl + Cl2  ----> CH2Cl2 + HCl

Product:: Dichloro methane (methylene chloride)


CH2Cl2 + Cl2 ----> CHCl3  +  HCl

Product:: Trichloro methane (Chloroform)


CH3Cl3 +  Cl2 ----> CCl4  +  HCl

Product:: Tetrachloro methane (Carbon tetrachloride/Pylene)


I think you only need to know the names in bold. For your question, choose any of the following reaction BUT using butane and chlorine
Eg. C4H11Cl  + Cl2 ----> C4H10Cl  +  HCl

OR to be safe give acc. to the ques

CH3-CH2-CH2-CH2-Cl  +  Cl2 ----> CH3-CH2-CH2-CHCL2  +  HCl
  
   H H H  H                             H  H  H Cl
   | |  |   |                             |  |  |  |
H-C-C-C-C-Cl   + Cl-Cl---->  H-C- C-C-C-Cl       +  H-Cl
   |  |  |  |                             |  |  |  |
   H  H H  H                            H  H  H H

Don't understand anything.. pls. ask.. Just under the concept of chlorination ;) they may ask any other alkane next time
Draw the structures yourself you'll understand better

--- End quote ---

I am sorry VIn

but the q says that

Write a diff eqn for a  substitutuin reaction between butane and chlorine

Vin:

--- Quote from: Ivo on June 04, 2010, 11:02:52 am ---~VIN1094~, for w08, Q7) b) iii), I do not get it at all.  The mark scheme says either 1 or 2-chloropropane is the product of the reaction, and that HCl is not a product.

Please explain, many thanks in advance.

--- End quote ---

that is for c) iii) not b) iii) ;)

Vin:

--- Quote from: gaurav95 on June 04, 2010, 11:16:15 am ---I am soryy VIn
but the q says that
Write a diff eqn for a  substitutuin reaction between butane and chlorine

--- End quote ---


I just gave you an example of methane... and how to name ...


--- Quote from: ~VIN1094~ on June 04, 2010, 10:46:43 am ---
I think you only need to know the names in bold. For your question, choose any of the following reaction BUT using butane and chlorine


Eg. C4H11Cl  + Cl2 ----> C4H10Cl  +  HCl

OR to be safe give acc. to the ques

CH3-CH2-CH2-CH2-Cl  +  Cl2 ----> CH3-CH2-CH2-CHCL2  +  HCl
 
   H H H  H                             H  H  H Cl
   | |  |   |                             |  |  |  |
H-C-C-C-C-Cl   + Cl-Cl---->  H-C- C-C-C-Cl       +  H-Cl
   |  |  |  |                             |  |  |  |
   H  H H  H                            H  H  H H

Don't understand anything.. pls. ask.. Just under the concept of chlorination ;) they may ask any other alkane next time
Draw the structures yourself you'll understand better

--- End quote ---

Got it?

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