Qualification > Sciences
ALL CIE CHEMISTRY DOUBTS HERE !!
Deadly_king:
Jun 09 p4 No 8
b)(ii) KPC = Concentartion of PCBs in fats / Concetration of PCBs in water
The above mentioned KPC should have a high value since from the paragraph written above, we can note that PCBs are highly soluble in fats (the main components of the Inuit diet). Therefore we can conclude that PCBs will be more soluble in fat than in water. Since PCBs is more soluble in fats, it will have a greater concentration in fats rather than water.
c)(i) Four spots were observed after the first solvent has been used. Spots which are just vertically above another spot s counted as one spot only.
(ii) Spot at the bottom.
(iii) Spot at the very top.
If you need more explanation, let me know :)
moon:
Thanks a lot. :)
Deadly_king:
Jun 09 p4 No 9
a)(i) You just need to draw an exact copy of the kevlar structure just below it. Then you need to show how they are bonded by hyfrogen bonds which occur between on O atom from C=O and one H atom from the opposite N-H.
In other words the bond will be formed from an O atom from the already drawn kevlar structure to a H atom from the structure you'll be drawing.
NOTE : Hydrogen bonds take place only between a H atom and an electronegative atom like oxygen, nitrogen and chlorine.
cs:
I have a doubt, what is the difference between elimination and reduction in organic chemistry..?
Deadly_king:
--- Quote from: cs on October 15, 2010, 05:43:26 am ---I have a doubt, what is the difference between elimination and reduction in organic chemistry..?
--- End quote ---
That may depend upon the different reactions. Do you have any example ???
Reduction -----> Redox reaction where a substance is reduced.
Elimination -----> A molecule is formed as by-product from the reaction. Usually it's water.
Examples :
i) When an aldehyde is reacted with a reducing agent like lithium aluminium hydride dissolved in ether, a primary alcohol is formed.
This is reduction as the aldehyde is reduced to a primary alcohol. :)
ii) When an alcohol is reacted with concentrated sulfuric acid at a temperature of 180oC, an alkene is formed with water as by-product.
We say water is being eliminated from the alcohol and the reaction is known as elimination ;)
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