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Salters Chemistry: 2854: Chemistry By Design 28/06/05 watch

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    I'm going to fail this paper so badly... I tried reading the textbook, reading the revision guide, and finally resorted to beating myself over the head with it, hoping that some of it might be absorbed...





    ...it wasn't.

    So...Screwed...
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    That was a hell of a lot easier than i was expecting. They even gave you NaBH4 as a reagent in the data sheet! n.m.r and infra-red was simple, some tough-ish calculations and standard stuff on chromophores and delocalisation. Little bits were tough, eg. I'm not sure where the marks were for some of the 4+ mark writing aswers, but pretty easy i thought, Anyway - that's my analysis - NO MORE EXAMS :cheers:
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    I'll agree that it was easier than i expected

    I got a bit freaked out by the IR - nmr 8 marker because a lot of the transmittances could be for an alcohol AND an ester or a carboxylic acid AND an ester - so it could have been eithre but i cracked it eventually

    Couple of things i wasn't sure on:
    e.g. what is the reaction that turns the ring structure (GBL maybe?) into GHB. I thought about reduction and then realised you were adding one water molecule so thought hydrolysis but i wasn't sure at all

    Also what the beep is a pharmacophore? And what was it on that one where you had to circle it?

    Oh and with the coupling agent, obviously you took the bit of the molecule that wasnt' derived from X but what was the group that would be lost when the two bonded????
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    A pharmacophore is the part of a molecule which gives it its pharmacological properties, I think

    I didn't think it was too bad really, much better than the Materials paper anyway. But then again, as long as I have an A and a B in my other subjects, I only need a C in chemistry anyway, whereas I suppose a lot of you need (or want) A's or whatever. I don't envy you that!
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    wot did u lot put as the IR spce? wot copmound was it?
    also what did you put as the last question (IM foreces between cotton/polyester questin)
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    what do you all mean by nmr? Did i miss somehting?
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    For the IR i ended up putting the ester because if it had of been the carboxylic acid then the transmittance at 3000 would have been wide because of hydrogen bonding

    For the very last question it took me a while but then i realised the dye and cotton both have -OH ... so they can both form hydrogen bonds BUT NOT WITH EACH OTHER. But polyester has C=O bonds so DY7 can hydrogen bond to the dye

    Any yes amie i need an A But i actually think i've got it *yes*
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    (Original post by kohlstream)
    what do you all mean by nmr? Did i miss somehting?
    In the question on GHB where it asked you about the IR spectum, once you've worked out what the compound was it asked you to describe the nmr of the compound
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    Oh bugger! Well I've messed that up a bit I think :rolleyes:
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    Good paper overall.
    I put the ester for the IR spec

    The question I struggle on for soooo long was the partial pressure calculation. I just looked at it and knew I couldn't do it.
    Also to work out [H+ ] from pH 2.9 it took me ages to work out how to use my calculator (it has really weird buttons) but I finally did.
    Wasn't too sure how extending the chromophore (right word?) meant the frequency of light absorbed decreased.
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    (Original post by Bekaboo)
    In the question on GHB where it asked you about the IR spectum, once you've worked out what the compound was it asked you to describe the nmr of the compound
    oh my god i am going to cry
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    Were there 3 different proton environments with 2 in each? Thats all I put for that part.
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    The question was identify which molecule the IR spectrum relates to from the ones in the question and say what the NMR would show. I put it was GBL (can't remember name, was something like this) - the one without O-H bond because there was no peak to correspond with O-H and all others had O-H group somewhere. Also showed it had C=O and C-O bond.

    With the question abut coupling reactions, what did u put as the other reagent? (the question before this was what type of compound is formed when the amine group is reacted with nitrous acid.. what's the answer to this as well?) I couldn't tell if the reagent we were trying to draw was the diazonium ion or if the other one was. Think I got this wrong.
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    did you have to mention covalent bonds in the last question or was it just that instantaneous induced between dye and cotton and hydrogen bonds between dye and polyester
    also for bond angles was it A-120 b-109
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    (Original post by kohlstream)
    oh my god i am going to cry
    Don't worry, I am too! I've always had problems with reading the questions through properly, and now that stupid habit could have really screwed up my chemistry grade!
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    (Original post by blacksox)
    also for bond angles was it A-120 b-109
    i got thos figures - can't remember which way round though (A or B). For the N one 109 and for the C=O one 120
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    (Original post by blacksox)
    also for bond angles was it A-120 b-109
    I thought it was A - 109 and B - 120 because nitrogen has a lone pair so effectivley is tetrahedral? Ahh I dunno.
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    That's what i put Ramaya
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    (Original post by Ramaya)
    I thought it was A - 109 and B - 120 because nitrogen has a lone pair so effectivley is tetrahedral? Ahh I dunno.
    I put the same as you but I wasn't completely sure. x
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    (Original post by blacksox)
    did you have to mention covalent bonds in the last question or was it just that instantaneous induced between dye and cotton and hydrogen bonds between dye and polyester

    I didn't, no, because it said "in terms of intermolecular forces" and besides i couldn't see how covalent bonds would form
    Were there 3 different proton environments with 2 in each? Thats all I put for that part.
    Well that's what i said - although i tried (Badly) to say which environments they were
 
 
 
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