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ALL CIE CHEMISTRY DOUBTS HERE !!

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Master_Key:

--- Quote from: moon on November 18, 2010, 12:39:18 pm ---Can someone please explain me nov.2008 q3,33,39 thanx in advance

--- End quote ---

Which paper and variant?

Hypernova:
Mr isn't 88.  its supposed to be strontium.

Could someone do it. no explanation, Just the stochiometry calculations needed. Thanks

yasser37:
November 06
21
37
39

Deadly_king:

--- Quote from: yasser37 on November 18, 2010, 01:24:06 pm ---November 06
21
37
39

--- End quote ---

Nov 06 p1

21. This one, you need to do it step by step. Find the number of chloroethanes when n=1, 2, 3 and 4 in the formula C2H6-nCln

When n=1 ----> C2H5Cl : You can have only one type.

When n=2 ----> C2H4Cl2 : You can have 2 types, one when both chlorine atoms are found on the same carbon and two, when each carbon atoms in the compound carries one chlorine.

When n=3 ----> C2H3Cl3 : You can have 2 types, one when all three chlorine atoms are found on the same carbon and two when one carbon carries 2 chlorine while the other carbon carries one chlorine.

When n=4 -----> C2H2Cl4 : Again 2 types. One when one carbon carries 3 Cl while the other carries one Cl. and two when both carbon atoms carries 2 Cl.

So in all that makes 7 types.

Answer is C

37. To have two organic products upon oxidation, you need to have two double bonds so that when both breaks two different compounds are obtained.

So number two is rejected since only one product will be formed. ;)

Now, to have a ketone, you need to have a secondary alcohol formed upon oxidation of the alkenes.

The answer is D

This is because the double bonds are arranged in such a way that upon oxidation you'll be getting two different compounds each carrying a ketone.

The third option however will produce a compound carrying two ketone groups while the other compound will form a carboxylic acid. So only compound 1 is appropriate. :)

39. Decolourise KMnO4 ----> he's talking about alkenes.

So it's going to be a dehydration process. Therefore number 3 being a carboxylic acid will not be dehydrated.

Both number 1 and 2 are alcohols and will be dehydrated by sulfuric acid to form alkenes.

Hence answer is B

NOTE : I've not had time to confirm my answers with the marking scheme. Do check it out and let me know if there are mistakes. ;)

$!$RatJumper$!$:
W04 Q3 pls
:)

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