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OCR A Chemistry Paper 2 Unofficial Mark scheme Watch

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    (Original post by TLS1234)
    For people wondering about the C13 question and why its a phenol is because it tells you its relative acidity, 5, which is below neutral and alcohols and phenols are relatively acidic, so it was essentially a judgement call on what info you already knew.
    Agreed, it HAD to be phenol and ketone due to the chemical tests, so anything within the nmr is just supporting that view imo, all carbons found within the aromatic ring were found in the aromatic range, regardless of what they were bonded to
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    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?
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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 either H2 and nickel catalyst or LiAlH4, but you might get one mark
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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?
    Yep its H2 and you need Ni catalyst
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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?
    Unfortunately yeah, as it technically still counts as a reagent even though its a catalyst
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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
    Yeah but apparently they also asked how they could check the purity. But I don't remember that.
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    did you have to name the oxidised products of butanal and butanoic acid? bcuz i just drew them i forgot what the question asked
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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?
    6.02x10^22 if I remembered correctly.
    (Original post by Shahani)
    I wrote about recrystallisation and filtration just forgot to say to check the melting point. would that still give me 2 ?
    Nah I think that person doesn't know what they're talking about. Definitely up to 4, but apparently it also asked how to check the purity (but I don't think it did so maybe 6 marks is possible).
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    (Original post by JayP454)
    did you have to name the oxidised products of butanal and butanoic acid? bcuz i just drew them i forgot what the question asked
    No you did not have to name them.
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    (Original post by AB199)
    Agreed, it HAD to be phenol and ketone due to the chemical tests, so anything within the nmr is just supporting that view imo, all carbons found within the aromatic ring were found in the aromatic range, regardless of what they were bonded to
    When it asked for functional groups, I put ketone and alcohol because at that point I didn't know it was phenol. I got the ketone-phenol thing for the next part, just wondered if alcohol is sufficient?
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    (Original post by Tuffyandtab)
    When it asked for functional groups, I put ketone and alcohol because at that point I didn't know it was phenol. I got the ketone-phenol thing for the next part, just wondered if alcohol is sufficient?
    Alcohol alone doesn't explain the lower pH of 5 so I'm not sure
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    (Original post by Tuffyandtab)
    Nah I think that person doesn't know what they're talking about. Definitely up to 4, but apparently it also asked how to check the purity (but I don't think it did so maybe 6 marks is possible).
    Don't be so toxic. The person in question is likely to be correct because the MS details how to mark 'asterisk' questions, and it's always based on putting into bands first. From specimen/practice material it is clear that the higher band expects a balance of info for all the points the question wants the candidate to address
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    i got 4 as well


    (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 ****
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    (Original post by AB199)
    Alcohol alone doesn't explain the lower pH of 5 so I'm not sure
    Slightly lower pH than 7 is explained by the weak acidity of phenol. Phenol will react with strong bases, but not weak bases such as sodium carbonate as illustrated by the observations.
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    (Original post by DoubleDoors)
    Slightly lower pH than 7 is explained by the weak acidity of phenol. Phenol will react with strong bases, but not weak bases such as sodium carbonate as illustrated by the observations.
    I am aware of that, I was explaining that alcohol alone wouldn't get the mark but thanks
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    (Original post by AB199)
    I am aware of that, I was explaining that alcohol alone wouldn't get the mark but thanks
    Oh sorry haven't been watching the thread!
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    (Original post by AB199)
    Yep its H2 and you need Ni catalyst
    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?
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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?
    Is it necessary to put filtration under reduced pressure followed by recrystallisation? The question asked for the purification steps from the impure solid instead of from the reaction mixture, so I started off straight by putting the procedures of recrystallisation. Will I lose any marks?
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    (Original post by AnnaRainbows)
    Why is it AgNO3 to measure the rate of activity/reaction? I put KCl because to see which one reacts fastest you need a displacement reaction? Cl displaces both iodine and bromine and then you can look at the speed... oh gosh
    I believe it's because during hydrolysis of a halgenoalkane, you get an alcohol and the halogen is lost. AgNO3 produces a precipitate of the halogen, so you can see how quickly it hydrolyses by how quickly the precipitate is produced.
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    (Original post by imstitch)
    Is it necessary to put filtration under reduced pressure followed by recrystallisation? The question asked for the purification steps from the impure solid instead of from the reaction mixture, so I started off straight by putting the procedures of recrystallisation. Will I lose any marks?
    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.
 
 
 
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