Chemistry Paper 4-theory- doubts =D

[kelly sheers]

plz can u explain the mechanism in this question 3 c(iii) . i am having trouble understanding it is this thing even in our syllabus ??
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s12_qp_42.pdf

i hope its clear

 

[AlishaK]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_41.pdf
@5 -iii) Step 4 AND b) ii .
Q6 ii) just wanna confirm.
I'll so so so thankful to anyone who helps me cause right now I'm having some of the worst times of my life with math and chem together. So please asap explain me?!
Jazak Allah Khair!
Cheers.

 

[knowitall10]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_41.pdf
@5 -iii) Step 4 AND b) ii .
Q6 ii) just wanna confirm.
I'll so so so thankful to anyone who helps me cause right now I'm some of the worst times of my life with math and chem together. So please asap explain me?!
Jazak Allah Khair!
Cheers.

Wa iyyaki
Don't worry sis. I think all the Saudi dudes have been influenced by the nikammi Saudi society. Even I am sufferring from mini strokes from time to time.
AlishaK and @everyone ImPoRtAnT CoNcEpT!!!!!!
Step 4 is the hydrolysis of the Diazonium salt. An important reaction but not mentioned in our books:
Look at the uploaded photo.
As for b(ii): It gives a white ppt with Br2 and is a disubstituted Benzene derivative- it's a phenol with 2 OH gps Tell me if I'm wrong please.
It shows a positive test result with the iodoform test: it has a CH3CO- gp.

 

[AlishaK]

Wa iyyaki
Don't worry sis. I think all the Saudi dudes have been influenced by the nikammi Saudi society. Even I am sufferring from mini strokes from time to time.
AlishaK and @everyone ImPoRtAnT CoNcEpT!!!!!!
Step 4 is the hydrolysis of the Diazonium salt. An important reaction but not mentioned in our books:
Look at the uploaded photo.
As for b(ii): It gives a white ppt with Br2 and is a disubstituted Benzene derivative- it's a phenol with 2 OH gps Tell me if I'm wrong please.
It shows a positive test result with the iodoform test: it has a CH3CO- gp.

LOL...what does Saudis have to do with my disastrous-life-right-now? hahaha...Thanks a lot thou. nd yea it ain't in our books! -___-....what's with these brits? Like we'll magically get something we'vent learnt before! :/

 

[knowitall10]

LOL...what does Saudis have to do with my disastrous-life-right-now? hahaha...Thanks a lot thou. nd yea it ain't in our books! -___-....what's with these brits? Like we'll magically get something we'vent learnt before! :/

I was just kidding btw But Saudis are a part of my depressing life...i keep wondering what they'll do in the future... jk!
Yeah I know, these brits are so vague it's not even funny. But don't worry, if I or anyone finds something that must be known and is not mentioned, InshAllah I'll make sure i tell everyone

 

[knowitall10]

Another important concept not mentioned in our books:

For Diazotization and coupling reactions:
Step 1 is the reaction between phenylamine and nitrous acid (nitric (III) acid), HNO2, to give a diazonium salt. This is what we know.
But nitrous acid is unstable and has to be made in a test tube, then the phenyl amine is added:
Nitrous Acid is made using sodium nitrite (sodium nitrate(III)) and dilute HCl:
NaNO2 + HCl ------> HNO2 + NaCl and then, the production of benezene diazonium chloride takes place (which we all know about)

 

[knowitall10]

Ring Activating groups (Substitute in the 2,4 and 6 positions): -alkyl, -OH, -NH3
Ring De-activating groups (substitute at the 3 and 5 positions): -COOH, -NO2, -carbonyl, -Cl2

If there're any more anyone wants to add to the list, or if I'm wrong, please do mention it
Your help is appreciated!!!

 

[HunzaZ]

Organic

i think we should revise difficult topics in the course! like main points!
BUT organic should be mastered as its a good like 20-30 marks in papers!!
so lets start with revising all organic!!
topics i find confusing are
-Group Trends
-Some calculations
-NMR

Any other feedback?[/quot
Yeah organic is a lengthy part.

 

[AlishaK]

Another important concept not mentioned in our books:

For Diazotization and coupling reactions:
Step 1 is the reaction between phenylamine and nitrous acid (nitric (III) acid), HNO2, to give a diazonium salt. This is what we know.
But nitrous acid is unstable and has to be made in a test tube, then the phenyl amine is added:
Nitrous Acid is made using sodium nitrite (sodium nitrate(III)) and dilute HCl:
NaNO2 + HCl ------> HNO2 + NaCl and then, the production of benezene diazonium chloride takes place (which we all know about)

Actually i know abt this cause my teacher taught us that way...
btw if insm quest they ask for this reaction's reagents and cndtns. do we write HNO2 as the reagent or NANO2/HCL? ! nd thanks a ton!

 

[AlishaK]

Ring Activating groups (Substitute in the 2,4 and 6 positions): -alkyl, -OH, -NH3
Ring De-activating groups (substitute at the 3 and 5 positions): -COOH, -NO2, -carbonyl, -Cl2

If there're any more anyone wants to add to the list, or if I'm wrong, please do mention it
Your help is appreciated!!!

i think it's NH2 instead of NH3...or is it both?
And also i was taught as: Electron releasing grps (subs at 2,4,6): ch3, -OH, -NH2
electron withdrawing grp(subs at 3,5): -COOH, -NO2, -COCH3

 

[waver525]

please heelp me with q 5 part a(iii) nd part b(iv) of this papr..

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s10_qp_41.pdf

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s10_ms_41.pdf

 

[1357913579]

Ring Activating groups (Substitute in the 2,4 and 6 positions): -alkyl, -OH, -NH3
Ring De-activating groups (substitute at the 3 and 5 positions): -COOH, -NO2, -carbonyl, -Cl2

If there're any more anyone wants to add to the list, or if I'm wrong, please do mention it
Your help is appreciated!!!

thanks alot for your cooperation can u please write the wquation for the reaction which sre the not in the cie book but come in the past papers

 

[xhizors]

Q1b1
i used MnO4- + 4h+ +3e ... equation
and in ms it uses 8H equation
how to know what to use ??
anyone plz!
http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_w12_qp_42.pdf
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w12_ms_42.pdf

 

[knowitall10]

i think it's NH2 instead of NH3...or is it both?
And also i was taught as: Electron releasing grps (subs at 2,4,6): ch3, -OH, -NH2
electron withdrawing grp(subs at 3,5): -COOH, -NO2, -COCH3

The amine group basically

 

[knowitall10]

Q1b1
i used MnO4- + 4h+ +3e ... equation
and in ms it uses 8H equation
how to know what to use ??
anyone plz!
http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_w12_qp_42.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_ms_42.pdf

Both links are the mark scheme. the question?

 

[Xtremite]

Q1b1
i used MnO4- + 4h+ +3e ... equation
and in ms it uses 8H equation
how to know what to use ??
anyone plz!
http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_w12_qp_42.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_ms_42.pdf

I think it has something to do with balancing of the electrons. Did you recheck your answer?

 

[Xtremite]

Both links are the mark scheme. the question?

Here's the qp: http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w12_qp_42.pdf

 

[knowitall10]

xhizors
Answer:
Because MnO4- ions must convert to Mn2+.
They are acting as oxidising agents since they convert Fe2+ to Fe3+

 

[knowitall10]

Can someone please post the link to the winter 11 examiner's report?
Jazakum Allahu Khair.

 

[PhyZac]

Can someone please post the link to the winter 11 examiner's report?
Jazakum Allahu Khair.

http://www.mediafire.com/?dgcbc88stxh5f#kbrqrvldz5e11