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OCR A Chemistry Paper 2 Unofficial Mark scheme Watch

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    (Original post by Shahani)
    what where the two other structural isomers for 3-bromophenylamine ? and what did you say about why there were isomers formed?
    I thought it was an elimination reaction so it just produced a double bond either side?
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    (Original post by Shahani)
    what where the two other structural isomers for 3-bromophenylamine ? and what did you say about why there were isomers formed?
    NO2 is a 3 directing group, NH2 is a 2,4 directing group

    Isomers will differ depending on whether you reduce it to NH2 before or after bromination

    If its reduced to NH2 AFTER bromination, only 3-bromophenylamine is formed because NO2 will direct to the 3 position
    If it's reduced BEFORE bromination, 2-bromophenylamine and 4-bromophenylamine will form instead because NH2 directs to the 2 and 4 positions
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    (Original post by ZoeBuck)
    I got 3480cm^3 for the volume in one of the questions
    I got 108 or 180 cm^3 I can't remember
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    (Original post by Asiangirl101)
    I got 108 or 180 cm^3 I can't remember
    I got 108cm3
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    (Original post by Asiangirl101)
    I got 108 or 180 cm^3 I can't remember
    I got 108 cm^3
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    How many repeat units was it?
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    (Original post by Lucy_starnes)
    What was the answer to the multiple choice about 0.1 mol and 0.1 mol makes how many atoms?
    Produces 1 water
    But 0.1 mole
    So it's 6.02 x 10^22
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    (Original post by Ashleigh123456)
    i think so yes
    It said give the structure of L, nothing about M. So I hope not.
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    (Original post by PuffyPrincess)
    It said give the structure of L, nothing about M. So I hope not.
    I think you just had to use the IR spec of M and N to make you realise that L was an ester, agreed there was nothing about showing the structure of M and N in the question
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    (Original post by medhelp)
    i got 4 chiral centres but im **** so im probably wrong

    other questions i vaguely remember

    butan-1-ol
    the oxidation well it was distil to aldehye and reflux to COOH wasn't it? both with K2Cr2O7/H+



    that recrystallisation was purity of benzoic acid after substituted with no2 + % yield



    MCQS:
    some bond angle ****
    I got 4 chiral centres too, and for the last question I'm sure they only Asked to draw out L not M and N?
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    (Original post by AB199)
    I think you just had to use the IR spec of M and N to make you realise that L was an ester, agreed there was nothing about showing the structure of M and N in the question
    Thanks guys I thought that too
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    (Original post by Tuffyandtab)
    I believe chromatography wasn't necessary. I put filtration under reduced pressure followed by recrysalisation. Didn't it want to know how to purify it?
    I wrote that too but also dissolve in ethanol first, but many people are saying melting points .. so I'm unsure now
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    (Original post by M.E.L)
    I wrote that too but also dissolve in ethanol first, but many people are saying melting points .. so I'm unsure now
    The question specifically asked how to 'check the purity', idk what that means but I'm guessing something like chromatography or melting point determination to check if its pure or not
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    Surely you don't have to show M and N; it wasn't asked in the question. Also probably would have been more marks if they wanted all three structures to be identified.
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    (Original post by stubyyyyy)
    Surely you don't have to show M and N; it wasn't asked in the question. Also probably would have been more marks if they wanted all three structures to be identified.
    Also why would they ask that if M and N are implicit in your structure of L, that requires no thinking whatsoever lol
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    (Original post by Asiangirl101)
    Produces 1 water
    But 0.1 mole
    So it's 6.02 x 10^22
    Same
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    What are we thinking for grade boundaries? I thought that was pretty easy and I finished before my extra time which I never do... So I'm thinking high grade boundaries for that one?
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    What was Question 16 and 17 about?
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    Was amount of water molecule 6.02x10^22?
    For organic compound for complete combustion was it C3H9?
    For naming the compounds I put both 3-methyl hexan-1-ol
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    (Original post by AB199)
    The question specifically asked how to 'check the purity', idk what that means but I'm guessing something like chromatography or melting point determination to check if its pure or not
    I put melting point, if compound is pure then the melting point will be over 1-2 degrees. You can also compare with the actual boiling point too, although I don't think I mentioned that part

    I never thought about chromatography either, but dissolving the solid in a solid then running a TLC against pure 3-nitrobenzoic acid should also show how pure it is.

    Only problem I had with the paper was that stupid question about beta-carotene - I got 11 C=C bonds, but then I left the rest blank so thats 2-3 marks already gone.
 
 
 
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