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

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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...


I wrote about optical isomers but I'm not sure
Original post by mattyk5
Dissolves because it can make hydrogen bonds with water surely? due to -OH group?


Yes I had that in my mind, but water on the skin? Sweat? I don't know, it just didnt make sense to me lol.
GUYS, you know the tripeptide question, do you draw unit repeat format or a normal tripeptide with carboxylic acid and amine at either end?? (I did both)
Reply 1663
Original post by Lion2121
Yeah it will be
3 for finding H
1 for structure of H
1 for F
1 for G

and then 1 for what you got for your H and what you got for your F to get the structure of I


So for getting the alcohol structure wrong, you'd lose 3 marks?
Original post by maisym00
I wrote about optical isomers but I'm not sure


Chemical synthesis is a mixture of optical isomers
the other one produces single stereoisomer
Original post by rory58824
Something to do with why it dissolves, I began talking about blood but I think that's wrong. The ketone was 4 straight carbons with a methyl group in there as well if I can remember


I think it dissolves because it forms hydrogen bond with water in blood?
Original post by 5824
So for getting the alcohol structure wrong, you'd lose 3 marks?


no 1 as the alcohol was F
Original post by rory58824
Yes I had that in my mind, but water on the skin? Sweat? I don't know, it just didnt make sense to me lol.


i was thinking stitches on fingers so water when washing hands etc
Original post by maisym00
I wrote about optical isomers but I'm not sure


yes you are absolutely right it was a chiral carbon and bacteria tend to produce only one isomer i am a complete moron
Original post by sakuraton
GUYS, you know the tripeptide question, do you draw unit repeat format or a normal tripeptide with carboxylic acid and amine at either end?? (I did both)


repeat format, as a tripeptide forms polypeptide i think
Pla break down because of hydrolysis living the acid as the product and then the acid form hydrogen bond with water ??
Original post by milutin767
yes you are absolutely right it was a chiral carbon and bacteria tend to produce only one isomer i am a complete moron


OH SH*T....
I started talking about renewability.....-_-
i found the paper way too easy. What do u guys think about boundaries? i think it would be somewhere like 51
If I got the structure of F wrong would I get error carried forward for the other structures?


Posted from TSR Mobile
For the 7 marker analysis, i got the structure of G wrong, meaning I got F and I wrong , but still got H right as that was separate. If my working for H is right, what's the max I could get?


Posted from TSR Mobile
Original post by 5824
If you used calculator unrounded figures, you got 2.67, but if you used yoru rounded working figures, you got 2.66


I used calculator figures (fractions) and got 2.66
Can someone make an UNOFFICIAL MARKSCHEME please.
Original post by 5824
If you used calculator unrounded figures, you got 2.67, but if you used yoru rounded working figures, you got 2.66


No, calculator unrounded gave 2.66 for me. 2.65645.....
Original post by Lion2121
repeat format, as a tripeptide forms polypeptide i think


For the tripeptide, did it formed of 3 monomes given in the question or just 1 and repeat jt 3 times ??
Can anyone remember the values (mr and mass produced) for the percentage yield question? Not the answer just the values given

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