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POST-EXAM CHAT: OCR Chemistry- Rings, Polymers and Analysis - F324 thread Watch

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    i reallly hope that i got the points in that they wanted...
    the question said what difficulties might be faced if the 2 amino acids have similar structures.. i said finding a solvent that would be able to sufficiently separate them.. what did everyone else write
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    I put 3 and 5 I believe. Though I think the three marks were

    1) IR can be used to identify functional groups
    2) C-13 NMR can be used to determine the number of carbon environments AND...
    3) Which type of carbon environment it is (though data was not provided)

    So I reckon I've lost a mark on that.
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    (Original post by FoOtYdUdE)
    the one with 0-CH3 on the right hand side does that make any sense? :o:
    same woo! i thought i was the only one!
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    (Original post by desertwarrior)
    i reallly hope that i got the points in that they wanted...
    the question said what difficulties might be faced if the 2 amino acids have similar structures.. i said finding a solvent that would be able to sufficiently separate them.. what did everyone else write
    I put that they would have similar Rf values, though that is obvious so probably not worth a mark. Bad times.
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    ah I made some really stupid mistakes, like I knew the aspirin + paracetamol had an ester/amide but then i also wrote they had a ketone. agh.

    also now i'm not sure which ester i said was right, i convinced myself i put the one at the top right, but i also convinced i did the one that started (CH3)2
    so i'm not sure how i've done.
    came out of the exam fairly happy. would be happy with a B
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    (Original post by andy892)
    How many C13 peaks did everyone get?
    I think it was for carboxylic acids. And i think the two we had to compare were pentanoic acid and 2,2-dimethylpropanoic acid?
    Therefore, pentanoic acid has 5 C environments and the other ones has 3??
    That's if it was those carboxylic acids we had to compare..
    are you talking about the NMR spec?
    with 3 peaks, and they mentioned 5 isomers and we had to look at the esters?
    :lolwut:
    have i missed a question? i dont recall any 13C spec analysis

    although they did ask how can we use 13C to distuinguish between molecules
    -number of carb enviros
    -chem shift reveals the types of carb enviros
    -use these to create a structure for both and distinguish between the two

    rant, rant, rant, rant, rant.
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    (Original post by iambrodie)
    I put 3 and 5 I believe. Though I think the three marks were

    1) IR can be used to identify functional groups
    2) C-13 NMR can be used to determine the number of carbon environments AND...
    3) Which type of carbon environment it is (though data was not provided)

    So I reckon I've lost a mark on that.
    Yeah I think that's what the 3 marking points will be.
    However, I also said 3 and 5 in the text of my answer - i.e. "in this example, the two COOHs can be identified based on the type of carbon environments - in one example there is 3 and the other 5"
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    (Original post by Noble.)
    No, it doesn't work. You would end up with carbon having five bonds, which doesn't work.

    Woo. Thank you Noble! You have cheered me up! So it wasn't a ketone!
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    That NRM question really took the piss, might sound about dumb but i only counted 5 peaks and so did alot of other people i know who sat the exam. There was 7 peaks, but the two small peaks on the sides were really small and i dont thinks thats fair. Anyone else had this problem?

    I still put down facts from the NRM like there where 3 proton environments ect ect.. just trying to make up some lost marks because i knew i cudnt get it right already being rushed for time..
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    (Original post by Bubbalina)
    same woo! i thought i was the only one!
    I got the same. I think it was (CH3)2CHCOOCH3. It was the bottom right of the choices.
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    (Original post by JordanCarroll)
    are you talking about the NMR spec?
    with 3 peaks, and they mentioned 5 isomers and we had to look at the esters?
    :lolwut:
    have i missed a question? i dont recall any 13C spec analysis

    although they did ask how can we use 13C to distuinguish between molecules
    -number of carb enviros
    -chem shift reveals the types of carb enviros
    -use these to create a structure for both and distinguish between the two

    rant, rant, rant, rant, rant.
    yes that's correct. But it may have been useful (or even necessary) to state in your answer the number of carbon environments in each respective carboxylic acid.
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    (Original post by vazverma9)
    That NRM question really took the piss, might sound about dumb but i only counted 5 peaks and so did alot of other people i know who sat the exam. There was 7 peaks, but the two small peaks on the sides were really small and i dont thinks thats fair. Anyone else had this problem?

    I still put down facts from the NRM like there where 3 proton environments ect ect.. just trying to make up some lost marks because i knew i cudnt get it right already being rushed for time..
    It wasn't really unfair, especially considering it's actually impossible for there to be five peaks.
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    (Original post by iambrodie)
    I put that they would have similar Rf values, though that is obvious so probably not worth a mark. Bad times.
    i wrote what you did,
    similar Rf, as similar structure=similar properties, so wont separate ranted abit on those two lines
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    (Original post by Noble.)
    It wasn't really unfair, especially considering it's actually impossible for there to be five peaks.
    Noble: did you give any thought to that thing I asked you? Or at least quoted you for..
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    (Original post by andy892)
    yes that's correct. But it may have been useful (or even necessary) to state in your answer the number of carbon environments in each respective carboxylic acid.
    ahhh i see what you mean now, thinking i missed like a page or something D:
    but yeah, actually mentioning that wouldv definitely covered it all
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    (Original post by vazverma9)
    That NRM question really took the piss, might sound about dumb but i only counted 5 peaks and so did alot of other people i know who sat the exam. There was 7 peaks, but the two small peaks on the sides were really small and i dont thinks thats fair. Anyone else had this problem?

    I still put down facts from the NRM like there where 3 proton environments ect ect.. just trying to make up some lost marks because i knew i cudnt get it right already being rushed for time..
    come onnn, they even highlighted the peak to avoid that :/
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    (Original post by andy892)
    Noble: did you give any thought to that thing I asked you? Or at least quoted you for..
    I'm not entirely sure, I can't imagine it's what they're looking for even if it would work.
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    (Original post by Noble.)
    I'm not entirely sure, I can't imagine it's what they're looking for even if it would work.
    It's just as worthy of the marks as other things.
    It shows lateral thinking and applying knowledge.
    The electron defficient carbon will certainly be prone to nucleophilic attack.
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    Has anyone got a markscheme?
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    (Original post by JordanCarroll)
    come onnn, they even highlighted the peak to avoid that :/
    Siriously the peaks were small and its not just me alot of other people also counted 5, i dont understand the point of making them small.

    I guess its kind of my fault for not looking hard enough then again i was rushed for time and soo was most others
 
 
 
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