Wjec ch4 2013

What do you guys think the grade boundaries are gonna be?

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So many big mark questions! The polymers question threw me as that was just a skim over in my revision! Went in feeling really confident and came out feeling awful :frown:

Reply 22

checkaid

Hi Guys and Girls !, Hope the exam went well for you. I found it okayish, I made some silly mistakes but hopefully not to much to cost me a grade. Just wanted to check What you put for the [7] Condensation Polymerisation Question.

It asked about synthetic and Natural Polymer. Giving examples.

I used ethane-1,2-diol and ethane-1-2-dicarboxylic acid. TO show ester bonds. Is this an example of synthetic or Natural. I didn't know which one it was.

Then synthetic i used 1-6-diaminohexane and hexanedioic acid. To show peptide bond. I hope got something of this [7] marker right. :frown:

Reply 23

Lost4468

Original post by checkaid

Hi Guys and Girls !, Hope the exam went well for you. I found it okayish, I made some silly mistakes but hopefully not to much to cost me a grade. Just wanted to check What you put for the [7] Condensation Polymerisation Question.

It asked about synthetic and Natural Polymer. Giving examples.

I used ethane-1,2-diol and ethane-1-2-dicarboxylic acid. TO show ester bonds. Is this an example of synthetic or Natural. I didn't know which one it was.

Then synthetic i used 1-6-diaminohexane and hexanedioic acid. To show peptide bond. I hope got something of this [7] marker right. :frown:

Synthetic I done 6,6-Nylon (same as you), and for natural I used aminoethanoic acid and 2-aminopropanoic acid. Pretty sure the amino acid one is natural.

Reply 24

checkaid

If you used aminoethanoic acid and 2-aminopropanoic acid. Is this showing peptide bond linkage again. Are we meant to show an Ester bond linkage such as H2COOCOOCH2. Just wondering.

Reply 25

shawneexo

Original post by Lost4468

Synthetic I done 6,6-Nylon (same as you), and for natural I used aminoethanoic acid and 2-aminopropanoic acid. Pretty sure the amino acid one is natural.

I did these ones too :smile:

yeah, polypeptides would be natural.

Original post by checkaid

If you used aminoethanoic acid and 2-aminopropanoic acid. Is this showing peptide bond linkage again. Are we meant to show an Ester bond linkage such as H2COOCOOCH2. Just wondering.

Yeah, both of mine showed a peptide link. I don't think you had to show an ester bond for the question, but it would still get the marks if it was correctly shown as natural/man made

Reply 26

checkaid

Thanks. Ah I see, cool. That is good, i labelled the repeating unit correctly so that is okay. But i guess I got the naming wrong. I put natural for the ester bond thing, and synthesis for polypeptide link. Oh well, hopefully it should not be a costly Mistake.

Reply 27

chloels

1

Original post by Lost4468

Synthetic I done 6,6-Nylon (same as you), and for natural I used aminoethanoic acid and 2-aminopropanoic acid. Pretty sure the amino acid one is natural.

Proteins are sequences of amino acids so it should be right! :smile:

I also did nylon 6,6 but got the name of the amine starter material wrong :/

Reply 28

checkaid

For the Low Resolution NMR:- It had C3H7Cl isomers. So I had one Low Resolution NMR with 3 peaks and the other with two peaks. Just wondering if anyone can remember where they put the peaks e.g. at 1.3, 0.9 delta and so on. I think I did right. It was quite weird that this paper, didn't fully test all reagents, and stuff. i guess it is down to the 6,7,8 marker questions they used.

(edited 11 years ago)

Reply 29

checkaid

For the mechanism it asked about ethene it had H+ added to it something like that. And then alcohol was formed. Would I be right in saying that the mechanism is an Electrophilic Substitution.

Reply 30

shawneexo

Original post by checkaid

For the Low Resolution NMR:- It had C3H7Cl isomers. So I had one Low Resolution NMR with 3 peaks and the other with two peaks. Just wondering if anyone can remember where they put the peaks e.g. at 1.3, 0.9 delta and so on. I think I did right. It was quite weird that this paper, didn't fully test all reagents, and stuff. i guess it is down to the 6,7,8 marker questions they used.

Gaah I don't like NMR! However, I did get one with 2 peaks and another with 3 peaks... If this is right then it's a miracle haha! Can't remember the chemical shifts though :/

Yeah it was a weird paper, I would've preferred more reagents and stuff but hey-ho!

Reply 31

checkaid

the question with capsacin [(CH3)2CHCH] and
gincerol or gingercerol. something like that. The question asked one test which would give the same observation. I used Fecl3 and purple solution. And the other I think it asked for positive test with glycerol only. did you people use K2Cr207 or something, because the OH in gingercerol, was on aliphatic carbon, so it could be oxidised.

Reply 32

Lizard cream

Original post by checkaid

the question with capsacin [(CH3)2CHCH] and
gincerol or gingercerol. something like that. The question asked one test which would give the same observation. I used Fecl3 and purple solution. And the other I think it asked for positive test with glycerol only. did you people use K2Cr207 or something, because the OH in gingercerol, was on aliphatic carbon, so it could be oxidised.

Thats what I did. :smile:

Reply 33

PeteJD

I read the NMR question and thought it only asked for 1-chloropropane and not both isomers -_- Dyspraxia strikes again!

Reply 34

stevo95

Original post by checkaid

the question with capsacin [(CH3)2CHCH] and
gincerol or gingercerol. something like that. The question asked one test which would give the same observation. I used Fecl3 and purple solution. And the other I think it asked for positive test with glycerol only. did you people use K2Cr207 or something, because the OH in gingercerol, was on aliphatic carbon, so it could be oxidised.

I put PCl5... I seem to remember secondary alcohols turning it cloudy... In hope....

That paper was minging :frown:

I feel so bad about it :frown:

goodbye uni :frown:

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Reply 35

piers.townsend

Hey guys.
Hated that exam, was awful to be perfectly honest. The six marker that talked about the two chlorine ones was bloody awful. I was writing about changing the side chain of methyl to a COOH haha. What an awful exam.
The 8 marker with A,B,C,D I completely messed up all of those marks, along with the polymer question I buggered up. Can't believe it after all the revision. Any other paper! Oh well hope and pray, sounds like you all did well though :smile:

well done guys.

Reply 36

emkate

Just realised I messed up the a b c d one, got propanoic acid and propanol :frown:

ahhhh silly mistakes! :frown:

I hate exams! :L

Reply 37

stevo95

Original post by piers.townsend

Hey guys.
Hated that exam, was awful to be perfectly honest. The six marker that talked about the two chlorine ones was bloody awful. I was writing about changing the side chain of methyl to a COOH haha. What an awful exam.
The 8 marker with A,B,C,D I completely messed up all of those marks, along with the polymer question I buggered up. Can't believe it after all the revision. Any other paper! Oh well hope and pray, sounds like you all did well though :smile:

well done guys.

Mate... I'm in the same boat as you haha! It was a minging paper! But maybe that's what we get for having a nice biology paper? Haha!

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Reply 38

Arthurnator

Original post by checkaid

For the mechanism it asked about ethene it had H+ added to it something like that. And then alcohol was formed. Would I be right in saying that the mechanism is an Electrophilic Substitution.

To answer your question it would be electrophillic addition or hydration (i think both will be accepted) as the double bond is attacked to form a carbocation intermediate which they also asked us about. then the remaining OH- attacks the carbocation to form the alcohol. And the next part of the question asked us about the mechanism with propene. that would be the addition of the proton to the side of the double bond with most hydrogens leaving the carbocation on the middle carbon making a secondary alcohol. (Markovnikov's) :smile:

Reply 39

Arthurnator

Original post by emkate