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OCR A2 CHEMISTRY F324 and F325- 14th and 22nd June 2016- OFFICIAL THREAD

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Original post by mattyk5
I used calculator figures (fractions) and got 2.66


Yes, I got something like 2.656... which is 2.66 to 2 sf.
Original post by Pikki1234
If I got the structure of F wrong would I get error carried forward for the other structures?


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Yes as it required no working out it was worth 1 mark, you'd probably lose the ketone mark as well thats it
Original post by WhatALad
Can anyone remember the values (mr and mass produced) for the percentage yield question? Not the answer just the values given


3.00 g and mr = 93? I think.
Guys there was a question about structure of C6H15NO2, what did you put ??
Original post by rory58824
That was a fairly pleasant exam, just the three marker on PLA had me thinking. 2.66g for the yield question anyone? And molar mass of the carboxylic acid was 74, so I presumed it was C2H5COOH


I also got 2.66g and C2H5COOH. What did you put for the PLA qu/ think the 3 marks will be for?

Original post by milutin767
what was that thing for lactic acid in bacteria/by chemical synthesis? i said something about getting a pure product rather than a mixture of products...


I noticed that it was chiral?? H group, OH, COOH and CH3? So thought that maybe the chemical synthesis produces mix of enantiomers whereas fermentation produced just one? Bit of a last minute guess after initially skipping it though.
Lolololol. I shouldn't troll, or should I?
Original post by anndz3007
For the tripeptide, did it formed of 3 monomes given in the question or just 1 and repeat jt 3 times ??


Amino acid is a monomer, it was 3 different amino acids from the question not one 3 times hence it was a repeat unit
Original post by EricPiphany
Lolololol. I shouldn't troll, or should I?


Please. Break our hearts.
Original post by mattyk5
i was thinking stitches on fingers so water when washing hands etc


Oh god, I wrote about them being photobiodegradavle on exposure to UV😕 Oops
Original post by marioman
3.00 g and mr = 93? I think.


And 61% percentage yield ☺️ And then I believe the Mr for Compound A was found to be 135?
Original post by Lion2121
Amino acid is a monomer, it was 3 different amino acids from the question not one 3 times hence it was a repeat unit


It wasn't a repeat unit they wanted though wasn't it a tripeptide? So with a full nh2 and cooh group at either end.
That was an awesome paper.
Proud to say like the trolls in TSR exam threads it was a walk in the park.
Original post by GawdHeresEmmie
And 61% percentage yield ☺️ And then I believe the Mr for Compound A was found to be 135?


That all sounds familiar!
Really nice paper, I have a feeling f325 is going to be a ***** though.


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Original post by milutin767
what was that thing for lactic acid in bacteria/by chemical synthesis? i said something about getting a pure product rather than a mixture of products...


Lactic acid has a chiral carbon, meaning chemical synthesis produces optical isomers whereas biological synthesis (fermentation) doesn't
Original post by Lion2121
repeat format, as a tripeptide forms polypeptide i think


Okay, I did the repeat format on the paper and another one at the additional answer page! I hope they don't mark it down >< I think I got in that paper 50/60 XD
Original post by rory58824
Please. Break our hearts.


So you put three chiral centers on the tripeptide like a good boy?
Original post by GawdHeresEmmie
It wasn't a repeat unit they wanted though wasn't it a tripeptide? So with a full nh2 and cooh group at either end.

I must have got it wrong then
Ketone for G and secondary alcohol for F , ester for I and carboxylic acid mr=74 anyone correct me f I'm wrong
Use of polyamide?

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