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    (Original post by lai812matthew)
    https://en.wikipedia.org/wiki/Zwitterion
    In chemistry, a zwitterion is a neutral molecule with both a positive and a negative electrical charge. Multiple positive and negative charges can be present. Zwitterions are distinct from dipoles, at different locations within that molecule.

    if there is a molecule with n amines and n carboxyls, wouldn't it be all protonated as long as the charge stays netural? (n-n=0)
    no no no - do not make this mistake! A zwitterion is a dipolar ion of an amino acid therefore only 2 opposing charges.
    When it no longer exists in the zwitterion form (when you add acid or alkali) then the R groups can have a charge
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    (Original post by sakuraton)
    Then can you explain this:

    http://www.ocr.org.uk/Images/79471-q...d-analysis.pdf

    http://www.ocr.org.uk/Images/61007-m...is-january.pdf

    January 2012, Question 3)b) Thank you!
    there is no aldehyde formed in those set of reactions - I've done that question before - you must have went wrong somewhere
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    (Original post by tcameron)
    no no no - do not make this mistake! A zwitterion is a dipolar ion of an amino acid therefore only 2 opposing charges.
    When it no longer exists in the zwitterion form (when you add acid or alkali) then the R groups can have a charge
    huh? i copy it from wikipedia. that's what concerns me. definition that i know about zwitterion: An ionic form of an amino acid that contains both positively and negatively charged groups. As both charges are present there is no overall charge.
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    It must be due to the C=C some how?? but i am unsure too, in the context of the question you try and get a form of a compound that looks like the answer. I think reduction of COOH is possible but not on our spec??
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    (Original post by lai812matthew)
    huh? i copy it from wikipedia. that's what concerns me. definition that i know about zwitterion: An ionic form of an amino acid that contains both positively and negatively charged groups. As both charges are present there is no overall charge.
    well to be fair, we all know they dumb it down for A levels and not all we do is exactly correct - stick to the specification as you will not get the marks if your zwitterion has more than 2 charges on it.
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    (Original post by lai812matthew)
    huh? i copy it from wikipedia. that's what concerns me. definition that i know about zwitterion: An ionic form of an amino acid that contains both positively and negatively charged groups. As both charges are present there is no overall charge.
    Please don't trust Wikipedia.
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    (Original post by tcameron)
    there is no aldehyde formed in those set of reactions - I've done that question before - you must have went wrong somewhere
    Well, I thought carboxylic acid can't be reduced and the mark scheme shows that carboxylic acid being reduced? I'm just confused, that is all.
    I know Aldehyde and Ketone can be reduced.
    I'm just gonna leave it and hope a nice paper tomorrow.
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    Do we need to learn the monomers that make Nylon and Kevlar?
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    (Original post by sakuraton)
    Well, I thought carboxylic acid can't be reduced and the mark scheme shows that carboxylic acid being reduced? I'm just confused, that is all.
    I know Aldehyde and Ketone can be reduced.
    I'm just gonna leave it and hope a nice paper tomorrow.
    the carboxylic acid was not being reduced - it was being dehydrated which is just removal of water - the carboxyl group wasn't even affected in that reaction.
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    (Original post by M0n1)
    does anyone have a copy of 2015 papers for F324??
    https://www.dropbox.com/sh/kwj0elokp...S-r2mI-Pa?dl=0
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    (Original post by Sarcastic Goats)
    Do we need to learn the monomers that make Nylon and Kevlar?
    Nope
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    lol @ all of you 99% ready........idek what tms does
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    (Original post by Sarcastic Goats)
    Do we need to learn the monomers that make Nylon and Kevlar?
    No but its known as Nylon 6,6 so 6 carbons on both the dicarboxylic acid and diamide
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    (Original post by lai812matthew)
    huh? i copy it from wikipedia. that's what concerns me. definition that i know about zwitterion: An ionic form of an amino acid that contains both positively and negatively charged groups. As both charges are present there is no overall charge.
    Look at all the OCR A questions involving zwitterions, with varying R groups. The R group is never affected in zwitterions (if we want to get the marks).
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    (Original post by shamsaidk)
    lol @ all of you 99% ready........idek what tms does
    Is the standard reference peak, is very large as all the protons are in the same environment
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    (Original post by shamsaidk)
    lol @ all of you 99% ready........idek what tms does
    Standard for chemical shift measurements (quoted from spec)
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    (Original post by tcameron)
    the carboxylic acid was not being reduced - it was being dehydrated which is just removal of water - the carboxyl group wasn't even affected in that reaction.
    AFTER the elimination of H2O, you see the word 'reduction' O.O
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    (Original post by shamsaidk)
    lol @ all of you 99% ready........idek what tms does
    TMS is the standard for all chemical shift measurements
    It has a chemical shift of 0
    it's structure is Silicon surrounded by 4xCH3 groups

    hope that helps
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    (Original post by CalistaJupiter)
    They don't all protonate… I did a past paper that had a 'zwitterion' with an extra cooh side group and the mark scheme said "reject if both cooh groups are shown to have donated a proton" because only groups directly involved in being an amino acid (eg RCH(NH2)COOH) actually protonate
    yh cus there are unequal number of cooh to nh2, my confusion is what if there was equal amount of both. the charge would still be neutral


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    Who's fasting during the exam tomorrow?

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