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F334 (19/06/2013 9:00AM) - Salters Chemistry (Chemistry of Materials) Revision Thread watch

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    (Original post by ElChapo)
    Heat under reflux and distil is a con, you cant do both, you just had to say distil.
    Marks:
    Acidified (1)
    Dichromate (1)
    Distil (1)
    Wasn't the question something like what are the conditions to oxidise an alcohol, and how could he make sure that only the aldehyde was produced or something? Or what was it?
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    (Original post by EdwinLo)
    Wasn't the question something like what are the conditions to oxidise an alcohol, and how could he make sure that only the aldehyde was produced or something? Or what was it?
    Yeah it wanted the reagent(s) and conditions to make sure you formed an aldehyde, and thats to distil it, refluxing would give you a carboxylic acid
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    (Original post by ElChapo)
    Yeah it wanted the reagent(s) and conditions to make sure you formed an aldehyde, and thats to distil it, refluxing would give you a carboxylic acid
    Damn that sucks I always thought you could "reflux and distil off the product" and my teachers never corrected me...So do you think that would lose 1 mark then? Would I get the other 2 for acidified potassium dichromate?
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    (Original post by Pandora's Box)
    Does this mean that it was neutral?
    Google is your friend. Quick search shows tyrosine neutral and polar (http://www.elmhurst.edu/~chm/vchembo...structure.html).
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    (Original post by EdwinLo)
    Damn that sucks I always thought you could "reflux and distil off the product" and my teachers never corrected me...So do you think that would lose 1 mark then? Would I get the other 2 for acidified potassium dichromate?
    Yes you should do, only 1 mark though
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    Is there an unofficial mark scheme?

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    What did people put for that rate question with the graph?
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    (Original post by ElChapo)
    Yes you should do, only 1 mark though
    Only 1 mark lost or only 1 mark gained?
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    (Original post by Mattywooda)
    Google is your friend. Quick search shows tyrosine neutral and polar (http://www.elmhurst.edu/~chm/vchembo...structure.html).
    I love, so it was definatly neutral?

    (Original post by EdwinLo)
    Damn that sucks I always thought you could "reflux and distil off the product" and my teachers never corrected me...So do you think that would lose 1 mark then? Would I get the other 2 for acidified potassium dichromate?
    Did you do that past papers? As these exact conditions have come up on several past papers.
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    (Original post by Richyp22)
    I love, so it was definatly neutral?



    Did you do that past papers? As these exact conditions have come up on several past papers.
    I did one, and that was my mock.
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    (Original post by EdwinLo)
    Only 1 mark lost or only 1 mark gained?
    Lost
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    I'm pretty sure tyrosine should be acidic, because the twitterion is neutral, and there is a phenol group as well?
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    (Original post by super121)
    What did people put for that rate question with the graph?
    That was a weird question. I said something along the lines that the rate increases as the concentration of Mn increases from x to y, as it's being used up; then as Mn's concentration starts to tail off from y to z it's because the product is being formed. I really don't know about that question.

    (Original post by CureSam)
    I'm pretty sure tyrosine should be acidic, because the twitterion is neutral, and there is a phenol group as well?
    Yes it should be acidic due to the extra phenol group
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    for me, this exam was better than f335!
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    (Original post by CureSam)
    I'm pretty sure tyrosine should be acidic, because the twitterion is neutral, and there is a phenol group as well?
    Regardless of what you think it's neutral. Unless your saying this source is wrong?

    http://www.elmhurst.edu/~chm/vchembo...structure.html
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    (Original post by Richyp22)
    Regardless of what you think it's neutral. Unless your saying this source is wrong?

    http://www.elmhurst.edu/~chm/vchembo...structure.html
    Yeah that source says it's neutral in water, but in the exam it was in NaOH
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    (Original post by :)ella)
    Yeah that source says it's neutral in water, but in the exam it was in NaOH
    Naoh wasn't mentioned in that specific question im afraid, it said only aqueous solution(in water).
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    (Original post by Richyp22)
    Naoh wasn't mentioned in that specific question im afraid, it said only aqueous solution(in water).
    Oh okay my bad, wow that was a mean question
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    (Original post by Richyp22)
    Regardless of what you think it's neutral. Unless your saying this source is wrong?

    http://www.elmhurst.edu/~chm/vchembo...structure.html
    I put down neutral, but I don't know if my reasoning was correct. Could you explain what would you write?
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    (Original post by EstebanK0)
    I put down neutral, but I don't know if my reasoning was correct. Could you explain what would you write?
    I said because the positive charge of the NH3+ group balances the negative of the COO- group.. I'm not saying that is right though :P

    To be honest I wouldn't be surprised if they actually allowed
    -neutral and justification
    or
    -acidic and justification

    I was torn which one to write and went for neutral in the end but it seemed pretty tricky.
 
 
 
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