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    (Original post by Don Pedro K.)
    What else couild you have put?
    That the effect of 2nd eq was negligible
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    For the assumptions I think one of them is that the initial conc is the same as the equilbrium conc
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    (Original post by ab9826)
    i dont think it matters as long as they didnt overlap
    I think it does matter unfortunately :/ Probs one mark
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    so basically we all agree that it was harder than usual right?
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    (Original post by Jerry162)
    Some answers I remember putting down:

    Multiple choice
    - decrease both pressure and temperature for more NO yield
    - Propane 1-2-3 triol
    - hexane at top with higher iodine conc.
    - only one of the addition leads to elimination (can't be chiral as no chiral carbon)

    H2S Qs
    - HS- was something x10^-5
    - pH was 4 something (4.02?)
    - assumptions: water does not dissociate to make any H+, [H2S]eq = initial conc., second ionisation is negligible due to tiny Ka

    Titration curve
    - 2 equivalence points, first one's half equivalent point is at 1.9, the other at 7.2, end point has pH of 13
    - to work out pKa1 look for pH at first half equivalence point

    Rate stuff
    -Br- was first order as proportional change to 1/t (which is proportional to initial rate) as Br- changes
    - units for rate constant I said mol^-3dm^9s^-1

    Clock reaction- for why phenol was in small conc. I said 1/t proportional to rate is only valid if less than 10-15% of the acid is used up etc
    - can't remember the questions, if someone can tell me I'll remember my answers

    Iodine clock test
    - solution turns blue black as thiosulfate is used up
    - that horrible 6 marker (I think I screwed up royally), I said first repeat experiments with all reactants but one at excess conc., then do so with other reactants, to work out orders with respect to them etc. then you can work out k via rate equation, then repeat reaction at various temperatures to get your various k and T values, then plot lnk vs 1/T graph then multiply the gradient by -R to get Ea

    Section C
    - products of alkaline hydrolysis were salicylate salt and methanol
    - difference between D and salicylic acids reaction with ethanol is D occurs a lot quicker and doesn't need conc. strong acid catalyst, and is non reversible
    -reagents were PCl5 and LiAlH4, skeletal formula was of ethyl salicylate
    -differences between acid and alkaline hydrolysis: one forms a salt and alcohol the other a carboxylic acid and alcohol, one is reversible (acid) the other isn't, alkaline requires one more step (protonation via dilute strong acid) to make carboxylate acid

    NMR
    - 3 peaks, a quartet a triplet and a singlet
    - 3-2-1 ratio
    - if I remember right, at 1, 2.5 and 3.5 ppm or something like that


    -I'll remember more answers if im reminded of the questions


    Much harder than past papers I thought :/
    come we develop this so we have a pretty much full on markscheme, if you remember anything that is here feel free to fill in the gap
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    (Original post by Don Pedro K.)
    I think it does matter unfortunately :/ Probs one mark
    oh crap never mind that means i lost a mark for nmr spec and then the integration ratio thingy!
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    Posted from TSR Mobile
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    What did everyone write about entropy of the group 2 hydroxides?
    Cant remember which ion we had to talk about but I wrote, smaller the ionic radii the greater the attraction between ion and h20 molecule therefore h20 is more closely bonded, which causes disorder to decrease, thus entropy decreases down the group 2 hydroxides.
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    (Original post by scrlk)
    Table of results
    Graph of ln t on y axis against 1/T on x axis
    Should get linear graph, constant gradient
    Calculate gradient
    Gradient = -EA / R
    Substitute in gradient, rearrange to find EA

    Am I missing anything?
    I don't think you're missing anything, you may have had to say it was negative gradient though
    (Original post by ramadeen)
    i agree, the questions weren't super hard. It was the fact that the type of questions was hard because i've never seen questions like this before. I really do think the grade boundaries will be lower than usual. I think it will be 69 for an A, what do you think?
    I don't know numerically but gb will def be lower than average.
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    is there gonna be a retake for this paper?
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    The answer for the first mc question about mechanisms was the one about elimination?
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    For the Ka expressions, you didn't have to include the water in them did you? I kind of froze when I saw there were 2 reactions for the same acid
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    (Original post by Feraligatr)
    Fingers crossed something similar will happen, I believe that question went off spec too (I'm also doing Edexcel bio)
    Theyve asked a question about diprotic acid titrations before though and that was totally allowed so I shouldnt think they will null it. Theyre allowed to apply the knowledge without sticking 100% to the spec.
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    (Original post by jwanjwan)
    come we develop this so we have a pretty much full on markscheme, if you remember anything that is here feel free to fill in the gap
    Why did tms have a stong peak ?
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    (Original post by C0balt)
    I don't think you're missing anything, you may have had to say it was negative gradient though


    I don't know numerically but gb will def be lower than average.
    if you drew a small sketch with a line with a negative gradient, would that count?
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    (Original post by ramadeen)
    so basically we all agree that it was harder than usual right?
    definitely. but do-able nonetheless
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    (Original post by _H_V)
    What did everyone write about entropy of the group 2 hydroxides?
    Cant remember which ion we had to talk about but I wrote, smaller the ionic radii the greater the attraction between ion and h20 molecule therefore h20 is more closely bonded, which causes disorder to decrease, thus entropy decreases down the group 2 hydroxides.
    I think it was more about solubility increasing because the dS total was more positive for barium hydroxide which meant that the equilibrium favours the product side more. The key is that they gave the equation dS=RlnK before that.
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    (Original post by lfcrules)
    Why did tms have a stong peak ?
    I wrote cos it has 12 hydrogens in one environment and its non polar
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    (Original post by lfcrules)
    Why did tms have a stong peak ?
    12 hydrogens in the same enviro produces a single intense peak
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    (Original post by luisgr8)
    The answer for the first mc question about mechanisms was the one about elimination?
    one bond forming one bond breaking
    (Original post by lfcrules)
    Why did tms have a stong peak ?
    12 equivalent hydrogens
 
 
 
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