ANY THING RELATED TO 7 MAY 2014 PAPER 22 CHEMISTRY AS LEVEL

[kingo44]

they didnt tell us to react with hot conc kmn04 it was simpply a test

 

[AbbbbY]

jesus abbu u think thats right i doont think so see they didnt tell us to react with conc kmn04 there was no space they only told us that alkene is present thus they showed us it reacted with kmn04 im goin crazzy here lol

Read this carefully. Calmly, carefully. Don't skim, read it all.

Data provided:
-> A compound has a molecular formula C6H12.
-> The compound decolorises Br2
-> When the compound is reacted with hot KMnO4, it gives only one organic product (lets say X).
-> When X is reacted with 2,4 DNPH, it gives a yellow/orange ppt
-> X does not test positive with Tollens Reagent.

Interpreting the data:
-> CnH2n. Alkene or cycloalkane
-> Alkene. Cycloalkne doesn't decolourise Br2
-> One product can be formed only in two cases. 1, if the C=C has one Carbon with TWO hydrogens attached and the other with 2 R groups. 2, if the C=C has exactly the same R groups on either side.
-> DNPH gives a yellow ppt => Carbonyl present
-> Tollens Reagent negative => Aldehyde not present => Product after Hot KMnO4 is a ketone.


This leaves you with THREE possible starting materials (i.e the alkene, C6H12).
1- 2,3 di-methyl but-2-ene
2- 2 methyl pent-1-ene
3- 2 ethyl-prop-1-ene

The most common answers were 1 and 2, and are both correct.

 

[kingo44]

wat abt cis trans

 

[kingo44]

so how many marks 9 right

 

[kingo44]

wait only 2 marks one mark for skeletal formula right

 

[AbbbbY]

so how many marks 9 right

Part i), the identification of the structure was like 5 marks, the ketone was another mark or two. Cis trans was 3 marks, I believe.

wat abt cis trans

What about it? You want the structures?

 

[kingo44]

so like those where onloy 2 marks

 

[kingo44]

yes i want them break me more jesusss

 

[AbbbbY]

yes i want them break me more jesusss

Let me know if you want the bombshell dropped for math too. I've got solutions of all the questions

 

[kingo44]

yyes i wrote that correcy tyesssssssssssssss

 

[kingo44]

i love u abby

 

[kingo44]

but mine little different i named them cis e and z isomerism

 

[AbbbbY]

i love u abby

Sorry bro. Not gay.

 

[AbbbbY]

but mine little different i named them cis e and z isomerism

Cis e and z? Whaa?

 

[kingo44]

wait r u girl

 

[kingo44]

the geometrical isomerism u need to name them jesuss

 

[kingo44]

i drew it correct but that hot conmc kmn04 is a bitch wat u think

 

[kingo44]

but where is cis and trans i wrote one cis and trans and the other i wrote it different

 

[basimnazir]

Ummm.. Excuse me?
What sort of alkanes have a pi bond and a sigma bond. And what sort of chemistry exists where a compound has JUST a pi-bond.

I might've have jumbled up the alkane thinking about alkene.
Alkenes have pi bond which have less Bond Dissociation Energy compared to the sigma bond in the Alkanes which have higher Bond Dissociation Energy. Sorry about the mixing part.

This isn't correct. Although, from what I recall, the question was how can butane be produced, but if you were to produce Bromine in an FRSR mechanism, it'll be in termination.

Br* + Br* -> Br2 (where * shows a radical)

CH3CH2* + CH3CH2* -> C4H10 was what I, and everyone else I've asked answered.

Ah! I got this wrong then in that case.

What??
The compound did not contain a Carbonyl group!! Carbonyl group was formed after reacting it with hot KMnO4 and it tested NEGATIVE with Tollens reagent so THAT was a Ketone, not the initial, starting compound. Besides, C6H12 can never be a carbonyl anyway -_-

Just read my comment again. Before SHOUTING IN A PUBLIC FORUM.
Geesh! You got it right, we all got it wrong. Does that make your "annoying face" -_- happy now?

 

[kingo44]

exactly what