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    (Original post by yoda123)
    I don't know what else I can do to revise, done all the pp, learned all the reactions, I really hope a proton NMR long answer question comes up and also the problems with optical isomers and how to separate them question
    Same. I have no idea what else to do and when i stop I feel guilty for not working. I hope the nmr question isn't too complicated though. What are you aiming for in this exam?
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    (Original post by KB_97)
    If you're going from an aldehyde to a carboxylic acid do you still have to reflux it with acidified potassium dichromate?
    no reflux is not required, i checked earlier in the book and theres no mention, only if you go from alcohol to carboxylic acid


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    (Original post by yoda123)
    I don't know what else I can do to revise, done all the pp, learned all the reactions, I really hope a proton NMR long answer question comes up and also the problems with optical isomers and how to separate them question
    Skim this over a few times between between now and the exam.

    https://goo.gl/nVvgw9
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    (Original post by yoda123)
    I don't know what else I can do to revise, done all the pp, learned all the reactions, I really hope a proton NMR long answer question comes up and also the problems with optical isomers and how to separate them question
    worst part is that the exam in afternoon, i just want it over and done with


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    (Original post by lai812matthew)
    there might be a zwitterion question for an amino acid with multiple groups of amine and carboxyl groups.
    If the alpha amino acid has an r group that has cooh or nh2 and you're asked to draw the zwitterion, do you have to also write them as coo- / nh3+ ?
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    I've done Legacy papers '02-'06, OCR A papers all at least twice and a couple of Edexcel papers. Just have to think I can't have prepared any more and not stress too much
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    guys i am really bad at naming besides the usual as stuff, what am i supposed to know how to name?


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    (Original post by KB_97)
    If you're going from an aldehyde to a carboxylic acid do you still have to reflux it with acidified potassium dichromate?
    (Original post by ranz)
    no reflux is not required, i checked earlier in the book and theres no mention, only if you go from alcohol to carboxylic acid


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    Yeah, no reflux for aldehyde. It's distillation for partial oxidation of primary alcohols
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    (Original post by KB_97)
    If the alpha amino acid has an r group that has cooh or nh2 and you're asked to draw the zwitterion, do you have to also write them as coo- / nh3+ ?
    remember overall neutral charge, so lets say there were 2 nh and 2 cooh then yh u do both coo- and nh3+ but if theres an uneven number u only give equal a charge if that makes sense?


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    (Original post by KB_97)
    Same. I have no idea what else to do and when i stop I feel guilty for not working. I hope the nmr question isn't too complicated though. What are you aiming for in this exam?
    I need around 174 UMS combined in the exams to get an A,just need that to meet my dentistry offer, don't care about A* at all
    Just hope I don't mess up somehow
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    (Original post by RetroSpectro)
    It could be shown on either side it does not matter as long as a full repeat unit is displayed
    Thank you!
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    (Original post by KB_97)
    If the alpha amino acid has an r group that has cooh or nh2 and you're asked to draw the zwitterion, do you have to also write them as coo- / nh3+ ?
    No. I remember seeing a question like this today where the R group unaffected was in the ALLOW section of the mark scheme.
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    (Original post by Rust Cohle)
    Skim this over a few times between between now and the exam.

    https://goo.gl/nVvgw9
    cheers man, will do!
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    Anyone got good question(s) on triglycerides/fatty acids etc.?
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    (Original post by yoda123)
    I need around 174 UMS combined in the exams to get an A,just need that to meet my dentistry offer, don't care about A* at all
    Just hope I don't mess up somehow
    Good luck! Hopefully the paper will be better than last year.

    (Original post by Rust Cohle)
    No. I remember seeing a question like this today where the R group unaffected was in the ALLOW section of the mark scheme.
    I looked up lysine (r group has nh2) zwitterion and the r group was not affected at all. But in acidic conditions below the isoelectric point the r group nh2 would turn to nh3+ And vice versa for aspartic acid that has cooh in the r group.

    Thanks!
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    i spoke to 10 of my friends doing this paper tomorrow, so glad we got 58/60 for the 2015 ahah all of us got that what a coincidence
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    (Original post by ranz)
    guys i am really bad at naming besides the usual as stuff, what am i supposed to know how to name?


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    Things will pretty much any functional group in our spec like nitro, phenyl, amine, carboxyl, hydroxyl, aldehyde, etc.
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    who wants to get bucked head after exam ???
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    Genuinely accepted that I will fail this tomorrow

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    (Original post by KB_97)
    If the alpha amino acid has an r group that has cooh or nh2 and you're asked to draw the zwitterion, do you have to also write them as coo- / nh3+ ?
    Don't know if someone's answered this already, but a zwitterion 'contains both charges so there is no overall net charge'. Hence only one NH2 is changed to NH3+, and one COOH to COO-. Otherwise there might not be 'no overall net charge'
 
 
 
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