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OCR A Chemistry Paper 2 Unofficial Mark scheme Watch

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    (Original post by dhr_jacobson)
    The problem I have is that my understanding of H NMR tells me that the bottom structure, which everyone seems to have gotten, contradicts the spectra
    No it was definitely the bottom structure
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    (Original post by Boss987)
    Acyl chloride. Most reactive right??
    I put that too..hope it's right
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    For the MCQ, if it was a benzene ring then alicyclic and saturated is wrong because each carbon has one delocalised electron so it's not saturated. But it might have been a cycloalkane.
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    (Original post by Ashleigh123456)
    At the end L was a Ester: CH3CH2COOCH2C(CH3)2CH3
    M was a carboxylic acid: CH3CH2COOH
    N was an alcohol : HOCH2C(CH3)2CH3

    (although i'm pretty sure you could've had the groups the other way around too)
    did we also have to find M AND N or just L?
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    (Original post by aliyagg98)
    did we also have to find M AND N or just L?
    Just L mate. That guy is on cheese
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    Guys i bullet pointed the Purity long answer kinda worried now....i kinda learned to bullet point to make examiners life easier whilst reading by work.
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    (Original post by Desmos)
    For the MCQ, if it was a benzene ring then alicyclic and saturated is wrong because each carbon has one delocalised electron so it's not saturated. But it might have been a cycloalkane.
    it was cyclohexane or pentane cant remember
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    (Original post by perupanda)
    Not sure, but it is definitely important during recrystallisation to use a Büchner funnel as without it it will not filter. Possibly may lose one? But I guess most of the marks were for purity and % yield.
    when you use the Buchner funnel did you put wash it with distilled water?
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    (Original post by Boss987)
    Acyl chloride. Most reactive right??
    acyl chloride becuase when it dissolves in water it makes carboxylic acid and hcl therefore most acidic
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    (Original post by Boss987)
    71% yield.
    Did anyone get 95 repeat units?
    Ester for hydrogen NMR. This includes 3 CH3.
    At the end L was a Ester: CH3CH2COOCH2C(CH3)2CH3
    M was a carboxylic acid: CH3CH2COOH
    N was an alcohol : HOCH2C(CH3)2CH3 (Ashleigh)
    recrystallisation for the method.
    Phenol with ethanone joined together. for C NMR.
    https://www.thestudentroom.co.uk/att...2&d=1497870262
    Butan-1-ol + 2O] --> Butanoic acid and Water, using acidified potassium dichromate and under reflux
    Butan-1-ol + [O] --> Butanal and water, using acidified potassium dichromate and distillation technique (AnnaRainbows)
    Diol more soluble as it has two hydroxyl groups.
    Alcohol forms h bonds with water so soluble.
    https://www.google.co.uk/url?sa=i&rc...97957876618458
    Beta carotene Q
    C40H56 + 11H2 --> C40H78 (TuffyandTab)

    MCQ
    BDCBDCACCBCAACB (tamoni4)
    AgNo3
    C7H14 - molecular formula
    Addition reaction (economy)
    Trigonal planar - Atom no. 3
    3 peaks for NMR in MCQ
    3 or 4 Chiral carbons??
    Acyl chloride + primary amine = amide MCQ
    Alicyclic and saturated??

    Good Paper!!!
    Wait did we need to identify M and N in the final Q???
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    (Original post by bethanydewhirst)
    i did a question in one of the specimen papers and forgot to include a bit of it but because they specifically asked for that bit as well in the question I got no marks even though I wrote about everything else because of the levelled markscheme. Not sure if it'll be the same for this one though, it depends what's required for each level
    I swear it said how would you purify and not how would you purify AND check the purity?
    it asks *you* to check the purity via % yield so hopefully not putting the melting point check should be ok
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    (Original post by Desmos)
    For the MCQ, if it was a benzene ring then alicyclic and saturated is wrong because each carbon has one delocalised electron so it's not saturated. But it might have been a cycloalkane.
    Unsaturated simply means no double bonds, benzene rings are saturated
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    (Original post by callumabbott99)
    Unsaturated simply means no double bonds, benzene rings are saturated
    Benzene is unsaturdated
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    (Original post by Asiangirl101)
    Produces 1 water
    But 0.1 mole
    So it's 6.02 x 10^22
    was a diprotic acid with a monobasic base. therefore 1:2, so 0.1mol of NaOH reacts with 0.05 mol acid, and 1 mol of acid forms 1 mol of water, so 0.05mol water forms, which is 0.05*6.02*1023= 3.01*10^22
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    (Original post by callumabbott99)
    Unsaturated simply means no double bonds, benzene rings are saturated
    Benzene is unsaturated, saturation means you can't add any more groups to it. Benzene is C6H6. Cyclohexane is C6H12, so you can add more H's to benzene so it's unsaturated
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    (Original post by aliyagg98)
    did we also have to find M AND N or just L?
    Just to recognise that they were C.acids and alcohols, you didn't need the structure
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    (Original post by Toffo132)
    was a diprotic acid with a monobasic base. therefore 1:2, so 0.1mol of NaOH reacts with 0.05 mol acid, and 1 mol of acid forms 1 mol of water, so 0.05mol water forms, which is 0.05*6.02*1023= 3.01*10^22
    I think it was double that. Somebody explained it before but I can't rememberer where now hahahah

    Basically, because 0.1 mole of the acid reacted with 0.1 mol of NaOH, the acid was a limiting reagent so not all of it reacted. But all of the NaOH would so it was 0.1 mol of NaOH equal and 0.1 mol of water
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    (Original post by Sam Mccready)
    when it had the question about hydrogenation of the cyanide I put H2 as a reagent but not nickel, would you need nickel? or am i completely wrong?
    you need the nickle, RCN doesnt readily react with H2, much like C=C
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    (Original post by thursdaygirl)
    Was it correct to put H2 and nickel for BOTH times it asked something about reduction (think one of them was a benzene ring with a ketone group on it?).

    I started getting confused about potentially using LiAlH4, but put H2 and nickel twice to be safe

    edit: think i remember the Qs. One involved CN and one was benzene with one ketone group. put H2 and nickel for both, but were they trying to trick us? Does one not work with H2/nickel?
    For a benzene ring you need Tin(Sn) and Conc. HCl
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    (Original post by medhelp)
    I swear it said how would you purify and not how would you purify AND check the purity?
    it asks *you* to check the purity via % yield so hopefully not putting the melting point check should be ok
    maybe, I can't really remember 100% but i'm pretty sure it did ask for both. you should check with your teacher when they see the paper
 
 
 
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