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

  • View Poll Results: How did you find this paper?
    Very easy (~74 for an A)
    9
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    Easy (~71 for an A)
    11
    22.92%
    Average (~65 for an A)
    21
    43.75%
    Hard (~61 for an A)
    6
    12.50%
    Very Hard (~58 for an A)
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    2.08%

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    (Original post by EstebanK0)
    I did that. What do you guys put down for the conditions + reagents for alcohol to aldehyde?
    Heat under reflux with acidified potassium dichromate and distil off in situ as the reaction progresses.
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    (Original post by EdwinLo)
    Heat under reflux with acidified potassium dichromate and distil off in situ as the reaction progresses.
    Damn. I just wrote heat under reflux with potassium dichromate.
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    This seemed like a really easy paper at first and now I think we'll all have made a few silly mistakes...

    which is good for grade boundaries
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    Was the zwitterion overall basic or neutral? I spent a while debating whether the phenol will dissociate in water and in the end decided that it won't and the molecule will remain neutral. I then argued in the following question because there's a balance of charge the pH remains neutral.

    If I got the first part wrong (zwitterion was in fact basic) will I get e.c.f on the following question?
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    (Original post by Pucilowski)
    Was the zwitterion overall basic or neutral? I spent a while debating whether the phenol will dissociate in water and in the end decided that it won't and the molecule will remain neutral. I then argued in the following question because there's a balance of charge the pH remains neutral.

    If I got the first part wrong (zwitterion was in fact basic) will I get e.c.f on the following question?
    Wait so in the zwitterion does the phenol OH group become O-? Really unsure about this as that is what I put and I'm not sure if it's right.
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    (Original post by EdwinLo)
    Wait so in the zwitterion does the phenol OH group become O-? Really unsure about this as that is what I put and I'm not sure if it's right.
    This is my question. Whether the phenol groups dissociates or not determines whether the zwitterion ends up basic or neutral. I think it does indeed dissociate and the overall charge ends up being 1- so it is alkali.

    Question is, will I get e.c.f on my explanation in the next question.
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    (Original post by EdwinLo)
    Wait so in the zwitterion does the phenol OH group become O-? Really unsure about this as that is what I put and I'm not sure if it's right.
    Yeah, phenols react with NaOH. Think it was acidic due to the phenol
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    (Original post by aWildPidgey)
    But h2o wasn't in the rate determining step even though it was in the rate equation

    I thought that if it was in the rate equation it was in the rate determining step

    (Original post by Richyp22)
    Yh I know thats why I got super confused and changed my order of water from 2 to 0. As if water isn't in the slow step it can't be in the rate equation? Maybe it's something to do with the intermediates formed from water.
    You require 2H2O to give the one OH in the rate determining step, so it made sense water was to the order 2, because effectively you were using two waters.
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    (Original post by Mattywooda)
    Yeah, phenols react with NaOH. Think it was acidic due to the phenol
    No but I mean in the previous question where it is in water does the phenol OH become O-? Or am I remembering the questions wrongly...what was the question where you had to draw the zwitterion?
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    So you can only lose 18 marks to get an A?! For chemistry, I think that's ridiculous.
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    (Original post by DoeADeer)
    So you can only lose 18 marks to get an A?! For chemistry, I think that's ridiculous.
    Well it depends, 72/90 is often 90 UMS and A is like mid 60s so you can lose more than that generally and still get an A.
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    (Original post by EdwinLo)
    No but I mean in the previous question where it is in water does the phenol OH become O-? Or am I remembering the questions wrongly...what was the question where you had to draw the zwitterion?
    I wouldn't have thought so, but I guessed that bit :L

    Indeed it doesn't deprotonate: http://www.ebi.ac.uk/chebi/searchId....Id=CHEBI:58570
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    (Original post by Mattywooda)
    I wouldn't have thought so, but I guessed that bit :L

    Indeed it doesn't deprotonate: http://www.ebi.ac.uk/chebi/searchId....Id=CHEBI:58570
    Does this mean that it was neutral?
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    Absolutely beautiful paper. Got 1.69 for calculation, and 0.0867 s-1 for other one at end, really easy paper compared to January... January I heard the grade boundaries jumped so high because the exam
    Boards were under pressure from
    The government or something? You can see a trend with most exams having wayyy higher boundaries... I mean I got
    64 raw in January and got 63 ums only... So stupid should have got an A


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    What did people put for

    -If the zwitterion was neutral/acidic/alkali?

    -The cis/trans isomerism?
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    What are we predicting for an A?


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    (Original post by Futuristicmedic)
    What are we predicting for an A?


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    I'd say same as jan 13, i don't really think it was any easier to be honest
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    (Original post by hannah1994)
    I'd say same as jan 13, i don't really think it was any easier to be honest
    Would it not be slightly lower due to the calibre of students taking the test ? My school only does June exams , but at other schools only those retaking will be doing this paper


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    (Original post by EdwinLo)
    Heat under reflux with acidified potassium dichromate and distil off in situ as the reaction progresses.
    Heat under reflux and distil is a con, you cant do both, you just had to say distil.
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    Acidified (1)
    Dichromate (1)
    Distil (1)
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    (Original post by hannah1994)
    What did people put for

    -If the zwitterion was neutral/acidic/alkali?

    -The cis/trans isomerism?
    I said it would be acidic as the phenol group donates extra protons.

    Then for the cis/trans, I said the ring structure restricted rotation (like the c=c bond would in other e/z molecules) which allowed the amine groups to be on the same or opposite sides

    I'm hoping these are correct but don't hold me to it if I'm wrong!
 
 
 
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