[oHellno]

(Original post by TheAdrianoo789)
did you work out the structural formula of X?

Lol no, I was so confused, but it was a dipeptide.

[Robert McGeachan]

(Original post by EffKayy)
For the ones regarding the test I said

Y is an amino acid (ninhydrin test)
1 mole of HCL and NAOH reacted which means theres 1 NH2 and 1 COOH as NAOH reacts with COOH and HCL reacts with NH2.
Is this correct?

Also was the bromination mechanism 5 marks? :/ How could it be 5 markssssss!

No mate it was four. One for the formation on the electrophille and three for drawing the mechanism one for each stage.

[sunnybacon]

(Original post by EffKayy)
Can you pleaaseeeeeee answer my question above lool

Haha yeah okay

(Original post by EffKayy)
For the ones regarding the test I said

Y is an amino acid (ninhydrin test)
1 mole of HCL and NAOH reacted which means theres 1 NH2 and 1 COOH as NAOH reacts with COOH and HCL reacts with NH2.
Is this correct?

Also was the bromination mechanism 5 marks? :/ How could it be 5 markssssss!

Definitely 1 mark for the ninhydrin test bit, and you'll most likely get the other 2 marks for that second part too.
I dunno about the bromination mechanism, I think it was 4 or 5...probably one mark for the electrophile formation, then the other 3 for the various parts of the mechanism - getting curly arrows the right way round, possibly showing the cataylst being regenerated by H+ etc

EDIT: Looks like I've been beaten to it

[EffKayy]

(Original post by Robert McGeachan)
No mate it was four. One for the formation on the electrophille and three for drawing the mechanism one for each stage.

Thanks!

[vampirerahim]

(Original post by vampirerahim)
Oh okay
But wasnt HCL added to X to make Y

I guess ur right
but i am still thinkin
If X was a polymer and is heated the products wont have the same molecular formula as X....

[EffKayy]

(Original post by sunnybacon)
Haha yeah okay


Definitely 1 mark for the ninhydrin test bit, and you'll most likely get the other 2 marks for that second part too.
I dunno about the bromination mechanism, I think it was 4 or 5...probably one mark for the electrophile formation, then the other 3 for the various parts of the mechanism - getting curly arrows the right way round, possibly showing the cataylst being regenerated by H+ etc

EDIT: Looks like I've been beaten to it

Wooop I might have scraped a D

[TheAdrianoo789]

(Original post by oHellno)
Lol no, I was so confused, but it was a dipeptide.

Yeaahh same!

[MujtabaM]

(Original post by EffKayy)
Lets face it, its 4.

You're right...check pg 49..its 4

http://www.scribd.com/examville/d/33...ectroscopy-NMR

[CharlehH]

Hi everyone,

Hope the exam went well for everyone - the lovely diatomic nature of Nitrogen certainly had me going for a while, plus I originally put the Mr of H2O as 16... All fun.

Anyways, I'm just wondering if anyone else noticed an issue with the Data Booklet in their exams. I currently have the Issue 3 (November 2008) issue of the Data booklet, which I used in order to name the product "Glycine" I had found from hydrolysing the dipeptide. Referring to the Data Booklet, page 23 under "Carboxylic Acids" it reads, quoting:

1-Aminoethanoic (Glycine) NH2CH2CO2H

This, to me, seems incorrect. Surely it should read

2-Aminoethanoic (Glycine)

As the amino group -NH2 is attached to the second Carbon atom in the chain?

Well, either way, I put "Glycine" down, but, unless I am being completely stupid (which is more than possible), it seems to me that the Data Booklet supplied did not provide correct information (which could hinder the results of those who used the information provided to answer this question).

Is this worth making a fuss over? Or was it only me who decided to look in the Data Booklet to help name the molecule? :P

[Rory_M]

(Original post by EffKayy)
For the ones regarding the test I said

Y is an amino acid (ninhydrin test)
1 mole of HCL and NAOH reacted which means theres 1 NH2 and 1 COOH as NAOH reacts with COOH and HCL reacts with NH2.
Is this correct?

Also was the bromination mechanism 5 marks? :/ How could it be 5 markssssss!

Think the mechanism was 4 or 5, yes AA for ninhydrin, not sure about saying exactly one mole for each is necessary (i hope not!) esp as from formula it couldn't have more than one NH2 and one COOH.

For the mechanism, you get one for intermediate, one for eqn of catalyst thingy, one for final product (maybe) plus then arrows each score a mark sometimes.


EDIT: haha everyone's answered you now!

[keerthi3]

Can someone please post the mark scheme for this? Or when do you guys think that I'll be posted because I CAN'T WAITTTTTTTTT

[Misslassenza]

(Original post by keerthi3)
Can someone please post the mark scheme for this? Or when do you guys think that I'll be posted because I CAN'T WAITTTTTTTTT

Tess's can someone please post the unofficial mark scheme !!!


This was posted from The Student Room's iPhone/iPad App

[Sui-Kinxtar_kitty]

(Original post by vampirerahim)
theres no way it could have been n2
the formula had only one nitrogen which got reduced to NH2 to from amino acid in the next part

i mean think if u say there were 3 oxygen

2 were bound N to make NO2 and what about the 3rd ? COOH needs two more right

and its cant be NH2 for the second Nitrogen coz that was the whol point of second questions

Erm... No.... It was a dipeptide to start of with...

The reflux with HCL was acid hydrolysis to split the two into seperate amino acids... One being Glycine...

[Sui-Kinxtar_kitty]

(Original post by oHellno)
it was c4h8o3n2, it makes perfect sense.

Thank you

[Liam 09]

Only huge eff up for me would be that 6 marker on X that we are all talking about, otherwise seemed ok. Fire alarm mid exam spiced things up for everyone in my college too :P

[Next Level]

guys does anyone know how many marks the dot cross diagram was for the CN? and the phenol + bromine equation?

[Revent]

Using the power of the population, 67 seems to be what the grade boundary will be However, this does not take into account bias

[Revent]

(Original post by Next Level)
guys does anyone know how many marks the dot cross diagram was for the CN? and the phenol + bromine equation?

CN-2
Bromine Mech-4
Phenol and stuff being more reactive-3
Catalyst and other reagent-2

[sceptic_medic]

(Original post by Liam 09)
Only huge eff up for me would be that 6 marker on X that we are all talking about, otherwise seemed ok. Fire alarm mid exam spiced things up for everyone in my college too :P

Which part was 6 marks?? Are you talking about the tests made on Y? I thought that was 4

[Next Level]

(Original post by Revent)
CN-2
Bromine Mech-4
Phenol and stuff being more reactive-3
Catalyst and other reagent-2

I meant the q where there some multiple bromination as the answer with HBr etc