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    did people get like 9% for hydrogen percentage of mass
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    (Original post by chloeabeki)
    I put k[H+] for the new rate equation, if the concentration of propanal is so high so there's a massive excess, it won't limit the rate I think?
    I worked with the same logic.
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    (Original post by jakeysimps11)
    Same mate, 99% sure its correct
    It cant be tertiary because that doesnt change colour in acidified potassium dichromate
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    yes!
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    Before I forget these are some of my answers, not saying they're right by any means though

    ph values were something like 2.08, 2.32, 3.33
    for the salt/acid weird question i got 1.20
    9.09x10-3 for one question can't rememer which one
    9 peaks for the tick box question
    Last question I got the structure: CH3-O-C(CH3)2-CH2-CH2-OH
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    I said the rate would be 100 times bigger but now I figured that there will not probably be enough H+ to react it with so it is limited the the miles of H+. I got it wrong😭😭😭😵😵


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    Disgusting paper. 9 marks for that last question was so harsh, I said there's 5 peaks so there must be 5 Hydrogens in different environments, the absorption at X(forgot number) is caused by OH - alcohol

    Think i lost 7 marks on it or more :-( I said it was a diol.

    For the question about how to obtain alcohol from the reaction mixture I talked about fractional distallation.
    For the mark before that I said H2o with conc NaOH, I hope this is right :/
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    Can we complain because that paper that was a completely different arrangement with questions id never seen before. Next year is the new spec not this year.
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    Yeah that's what I got
    (Original post by Suits101)
    9 I think.
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    (Original post by j.ethers)
    Ok so for the last question we know it has to be a primary/secondary alcohol because of the dichromate reaction, but the O-H nmr peak was a singlet, suggesting the adjacent carbon to the alcohol group is itself bonded to no hydrogens. Therefore how can it be a primary or secondary alcohol??
    exactly!! didn't get it at all, i wrote down that it had to be primary or secondary but then forgot all about it aha! i think we will still get a few marks for our structyre though!
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    IF this helps anyone - I may be wrong

    1.
    Equation involved products of CH3COO- and H3O+ (wouldn't be penalised for no reversible reaction sign) (1)

    Equation involved products of CH3COOH2+ and NO3- (as above) (1)

    pH = 2.something (2 marks)

    pH = 2.something

    pH = 3.33 (something around this?) (4 marks)

    Ka = 9.09 x 10^-3 Units: mol^-1 dm3 (3 marks)

    [salt]/[ethanoic acid] = 1.20 (3 - 1 mark for [H+] = 10^-4.48)

    Chlorine atom is very electronegative and withdraws electron density from COO- ion (1)
    This makes COO- ion less negative and more stable and acidic (1)

    Can't remember the last part of Q1

    Random answers - may be wrong

    9 peaks
    Proton b - had alkyl groups, electron releasing, lone pair more available to accept H+ (converse for proton a which had a benzene ring)
    Why use PGA: biodegradable so it can be hydrolysed due to polar bonds (C=O/C-O) so sutures will dissolve over time
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    (Original post by thomaarrss)
    did people get like 9% for hydrogen percentage of mass
    yes i got 9.4%
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    (Original post by ishabennett)
    Can we complain because that paper that was a completely different arrangement with questions id never seen before. Next year is the new spec not this year.
    this threw me as well
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    loool that was just so hard, feel like I kept up as well as I could have and the low grade boundaries will keep my grade up
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    VERY tough exam, a lot of awkward questions that don't typically come up.

    I think that may just be the hardest CHEM4 paper I have came across, nevertheless I still think I done well - enough for an A anyways.
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    I worked so hard for that exam. I hate AQA
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    (Original post by thomaarrss)
    did people get like 9% for hydrogen percentage of mass
    Yeah can't remember the exact number but definitely around 10%. Because it was something like (23 / 233) x 100.
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    no one laugh but could it be

    (ch3)3-c-o-ch2-ch2-o-h

    i came up with that in two mins ((((((((
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    (Original post by jakeysimps11)
    Same mate, 99% sure its correct
    Can't be, it said it reacted to form a green solution with acidified potassium dichromate (VI) so it can't be a tertiary alcohol.
    But what I did get was similar: CH3 - O - C (CH3)2 - CH2 CH2 OH
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    Could R be HOCH2COCH2CH(CH3)2 as it must not be a tertiary alcohol?
 
 
 
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