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Chemistry AQA CHM4 (old spec) post exam discussion watch

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    (Original post by zaf1991)
    It was a secondary alcohol so I assumed you could not use acidified potassium dichromate. So I said Fehlings lol.

    For the carboxylic acid one I said NaHCO3 - Effervescence (even though I think I spelt it wrong on the paper lol) of CO2
    nah secondarys can still be reduced...but tertiary ones can't...i was gonna put Tollens, but then i remembered that there was a spare Hydrogen next to the C on the alcohol...so wouldnt it that be reduced too...i put acidified potassium dichromate
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    (Original post by zaf1991)
    Nothing special.

    I'm on ABB... 1 UMS off an A in Chem lol

    I'm doing work experience in a opthalmic surgery this year. I didnt apply for 2009 because I messed my AS up bad... Had some severe personal problems... and thought I was not going to get good grades last year either but I didnt do that bad. . I like module 4 so I did it again. Plus I hope it will get me in the mood for the beast - CHM5.
    dont get me started on CHM5...oh my dayssss...and CHM6 is worse :eek:
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    (Original post by zaf1991)
    Nothing special.

    I'm on ABB... 1 UMS off an A in Chem lol

    I'm doing work experience in a opthalmic surgery this year. I didnt apply for 2009 because I messed my AS up bad... Had some severe personal problems... and thought I was not going to get good grades last year either but I didnt do that bad. . I like module 4 so I did it again. Plus I hope it will get me in the mood for the beast - CHM5.
    hey whats the salary for an optometrist
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    (Original post by zaf1991)
    It was a secondary alcohol so I assumed you could not use acidified potassium dichromate. So I said Fehlings lol.

    For the carboxylic acid one I said NaHCO3 - Effervescence (even though I think I spelt it wrong on the paper lol) of CO2
    at least I'm getting something right :p: though I used Na2CO3 and said CO2 gas is released :erm:

    How hard is CHM5 compared to CHM4? I didn't sit it last year, so I'm unsure...
    Overall I think I lost not more than 10 marks... maybe
    For Kc did anyone get 0.16 ? And then answers for the questions after that were increase and then decrease ???
    ANd for the %yield/pressure/temperature, I wrote that the number of moles decreases and that the reaction was exothermic.
    anyone agree?
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    Exactly tertiary ones can't and both secondary alcohols and aldehydes reduce so you will not be able to separate them as they both will be reduced by acidified potassium dichromate which, is why I put Fehling's for aldehydes because secondary alcohols in Fehling's solution do not turn the solution red.
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    (Original post by SomeStudent)
    at least I'm getting something right :p: though I used Na2CO3 and said CO2 gas is released :erm:

    How hard is CHM5 compared to CHM4? I didn't sit it last year, so I'm unsure...
    Overall I think I lost not more than 10 marks... maybe
    For Kc did anyone get 0.16 ? And then answers for the questions after that were increase and then decrease ???
    ANd for the %yield/pressure/temperature, I wrote that the number of moles decreases and that the reaction was exothermic.
    anyone agree?
    with the kc im sure pressure has no effect on it...

    and yeh i agree with ur last points
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    (Original post by zaf1991)
    Exactly tertiary ones can't and both secondary alcohols and aldehydes reduce so you will not be able to separate them as they both will be reduced by acidified potassium dichromate which, is why I put Fehling's for aldehydes because secondary alcohols in Fehling's solution do not turn the solution red.
    SH.IT!!! bye bye to my A
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    (Original post by SomeStudent)
    at least I'm getting something right :p: though I used Na2CO3 and said CO2 gas is released :erm:

    How hard is CHM5 compared to CHM4? I didn't sit it last year, so I'm unsure...
    Overall I think I lost not more than 10 marks... maybe
    For Kc did anyone get 0.16 ? And then answers for the questions after that were increase and then decrease ???
    ANd for the %yield/pressure/temperature, I wrote that the number of moles decreases and that the reaction was exothermic.
    anyone agree?
    CHM5 is not hard but when you get your result you tend to do a little worse than you thought. That was my worst Chemistry result last year and it's 120 goddamn UMS.

    I dont remember the Kc value I got. or any of the others for that matter lol.
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    (Original post by Circularmover)
    with the kc im sure pressure has no effect on it...

    and yeh i agree with ur last points
    Well they said bigger volume, so what I did was changed the volume from 5 to ten and the value of Kc was lower... but my initial answer was none as well
    I wrote acidified potassium chromate too... were these questions from past papers? COs if they were, we could just have a look at the mark scheme right now...
    the yield/pressure/temperature question was from a previous paper, it looked very familiar. =)
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    (Original post by Circularmover)
    SH.IT!!! bye bye to my A
    Don't worry it wasn't many marks and you seem to agree with me about everything else so we should be ok, god willing. Umm salary varies. If you have your own buisness then there is no limit just like a private dental surgery. If you work in the hospital and move towards a consultant level you will get around £75000+ but other places vary hugely (eg. specsavers). Locum's get loads of money so I hear. I think it will hugely dependant on where you work and who you work for.
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    (Original post by SomeStudent)
    at least I'm getting something right :p: though I used Na2CO3 and said CO2 gas is released :erm:

    How hard is CHM5 compared to CHM4? I didn't sit it last year, so I'm unsure...
    Overall I think I lost not more than 10 marks... maybe
    For Kc did anyone get 0.16 ? And then answers for the questions after that were increase and then decrease ???
    ANd for the %yield/pressure/temperature, I wrote that the number of moles decreases and that the reaction was exothermic.
    anyone agree?

    Agreed
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    (Original post by SomeStudent)
    Well they said bigger volume, so what I did was changed the volume from 5 to ten and the value of Kc was lowered... but my initial answer was none as well
    I wrote acidified potassium chromate too... were these questions from past papers? COs if they were, we could just have a look at the mark scheme right now...
    the yield/pressure/temperature question was from a previous paper, it looked very familiar. =)
    Some questions were from 2002-2003 papers. And there was one other one from later on 2005ish or something, I did so many papers I cant remember lol.

    Pressure does not affect Kc - it is a constant, therefore it remains constant unless temp is changed (I think).

    The yield one was increase and decrease of O2
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    (Original post by SomeStudent)
    Well they said bigger volume, so what I did was changed the volume from 5 to ten and the value of Kc was lowered... but my initial answer was none as well
    I wrote acidified potassium chromate too... were these questions from past papers? COs if they were, we could just have a look at the mark scheme right now...
    the yield/pressure/temperature question was from a previous paper, it looked very familiar. =)
    From what I can remember, the answers today are the exact opposite from the June 2007 paper.
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    (Original post by Sabbir.M)
    From what I can remember, the answers today are the exact opposite from the June 2007 paper.
    yup, just had a look at it.. exact opposite,except it's '06 paper
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    I haven't properly revised for CHM5 yet, but I've got four days to fix that
    Good luck to everyone :top:
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    (Original post by SomeStudent)
    yup, just had a look at it.. exact opposite,except it's '06 paper
    I didn't like that question when I did that paper for practice. I didn't understand how to work it out, so I just blindly thought they would never use that again (becuase it was a crap question :p: ). So you can imagine how I was like when I saw it come up :o:
    But it all clicked suddenly in the exam, well i think it did :p:
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    (Original post by Sabbir.M)
    I didn't like that question when I did that paper for practice. I didn't understand how to work it out, so I just blindly thought they would never use that again (becuase it was a crap question :p: ). So you can imagine how I was like when I saw it come up :o:
    But it all clicked suddenly in the exam, well i think it did :p:
    Exactly the same for me I revised for this module in December and I remember thinking wtf, but in the exam today it was fine I hope all of this work will be worth it
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    I'm pretty sure when you increase the volume you decrease the pressure for the Kc question.
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    What was the splitting pattern? does anyone remember?
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    yep cos its gaseous
 
 
 
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