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    i put less than 7 and methyl orange..

    damn.......
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    can anyone tell me if they reduced twice?
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    I can't remember specifically, but we may have needed to reduce twice too.

    It was definitely the whole alchols, carbonyls, carboxylic acids area twice.
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    what did every one put for the question in the unit 5 paper, it was regents and conditions for step3 and was worth 3 marks.
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    There are two possible routes:

    Oxidation using alkaline potassium manganate (VII), heating the mixture under reflux

    OR warm with iodine in sodium hydroxide solution
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    and the silicon dioxide question is related to the giant covalent structure of silica- many strong covalent bonds must be broke in order for silica to dissolve, and insufficient energy is available for this to occur at room temperature
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    oh well didint do that great...dont think i'll get the A i need now
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    (Original post by neutron)
    There are two possible routes:

    Oxidation using alkaline potassium manganate (VII), heating the mixture under reflux

    OR warm with iodine in sodium hydroxide solution
    Yes! Thats what I thought! It seemed weird to me that they stated the reagents for the iodoform afterwards though
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    I think the exam paper managed to repeat almost every organic reaction twice in the course of the two papers
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    chem unit 4 was ok but boy was unit 5 messed up what the hell was that Diazonium thinggyy doing there i compleatly forgot all about it.lol, anyways u lot looking forward to the C6B paper if u lot doing it??
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    (Original post by leo_014)
    chem unit 4 was ok but boy was unit 5 messed up what the hell was that Diazonium thinggyy doing there i compleatly forgot all about it.lol, anyways u lot looking forward to the C6B paper if u lot doing it??
    haha i guessed the diazo stuff and i guessed it right!!!! wot r the chances of tht lol.. well chuffed .. and about 6B..hell no got C4 on same day :eek:
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    Ah messed up this test ... if the boundaries are insanely low ... something like in the mid 50's i might get an A.
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    mid 50's low?!
    i messed up big time esp unit 4 i had the feeling that i was giving answers but wouldnt get the marks coz of the mark scheme. when i saw the 1st 2pages with all those reactions i freaked! waste of time learning it!
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    (Original post by BCHL85)
    I got
    EA1 = -303.5 kJ/mol
    Kp = 0.0394
    pH = 2.81
    pH(buffer) = 4.61
    and
    k = 0.001 mol^-1dm^3s^-1(rate constant)
    ditto
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    (Original post by neutron)
    and the silicon dioxide question is related to the giant covalent structure of silica- many strong covalent bonds must be broke in order for silica to dissolve, and insufficient energy is available for this to occur at room temperature
    yeah, i remembered that 2 mins before the finishing time. what a blissful moment! lol
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    i totally messed up the buffer calculation....
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    (Original post by senshi)
    haha i guessed the diazo stuff and i guessed it right!!!! wot r the chances of tht lol.. well chuffed .. and about 6B..hell no got C4 on same day :eek:
    What does the azo dye (product) look like?
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    (Original post by leo_014)
    chem unit 4 was ok but boy was unit 5 messed up what the hell was that Diazonium thinggyy doing there i compleatly forgot all about it.lol, anyways u lot looking forward to the C6B paper if u lot doing it??
    Do we have to memorise all the AS Level definitions for unit 6?
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    Ah, I forgot about SiO2 being a giant structure.. I at least put about the bonds requiring a lot of energy to break, so maybe I'll scrape one mark out of 3 (was it?) on that question. I did say they were double bonds though..

    Are you sure you could do an iodoform reaction as one of the two possible routes? Did you not need to remove a longer side chain by oxidisation? Well, I can't remember exactly, if it was only a methyl group I suppose either way would work.

    I'm going to remain hopeful I got an A.. Chemistry is my strongest subject, and I generally get As on past papers I have done, I just keep thinking about all the silly mistakes I did: Not saying "in dry ether" whenever I used LiAH4, which was quite a lot of times due to the two papers being so repetitive/similar on the organic; for the reaction profile, I drew the transition state as if it was a catalysed one, putting it as an extra part, rather than the peak.

    Hopefully despite of all those silly mistakes I got most right, I guess you're bound to remember the parts you got wrong, but it makes the wait for results even more agonising!
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    (Original post by Goddess)
    Do we have to memorise all the AS Level definitions for unit 6?
    Yes, it tests anything from A or AS level. I don't think this is too bad for chemistry though, because the A2 builds on what you did in AS more than any other subject, at least any other subject I do (sciences & maths).
 
 
 
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