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    Hey, Does anyone know where I can find Chem 2015 3x and 6x papers?
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    (Original post by _leenz)
    Hey, Does anyone know where I can find Chem 2015 3x and 6x papers?
    Which board?
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    (Original post by dpoojaraa)
    Which board?
    AQA
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    Anyone with ocr A found any questions that are really hard??
    (That aren't past papers)
    Posted from TSR Mobile
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    Hey can someone help me with this questions :

    Why do have to filter zinc (reducing agent) during a vanadium experiment before potassium manganate ( oxidising agent) is added?? there is 3 or 4 marks involved with this question. can someone help?
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    (Original post by FREYA2898)
    Hey can someone help me with this questions :

    Why do have to filter zinc (reducing agent) during a vanadium experiment before potassium manganate ( oxidising agent) is added?? there is 3 or 4 marks involved with this question. can someone help?
    is this on the empa exam??
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    (Original post by chocolatte123)
    is this on the empa exam??
    No sorry, I got this from a past paper question and was wondering what the answer is. I do ISA anyway
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    Hey is anyone here doing Chemistry 3X? This is the AS empa resit
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    Does anyone have a copy of last year's a2 ISA and EMPA with the mark schemes?
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    (Original post by shiney101)
    Does anyone have a copy of last year's a2 ISA and EMPA with the mark schemes?
    The mark schemes are now online I think on the AQA website not sure about the papers
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    how are people prepping for the 2016 chem6x paper?
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    I've done the a2 empa for bio and chem (aqa - bio6x and chem6x)
    just got the as resit chem 3x left to do on Wednesday
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    Can someone help out in e (ii) ?
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    (Original post by PlayerBB)
    Can someone help out in e (ii) ?
    think about how much of the crystals would be dissolved at the start, and how much would still be dissolved when it is cooled down
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    (Original post by samb1234)
    think about how much of the crystals would be dissolved at the start, and how much would still be dissolved when it is cooled down
    Ahhh right, thank you!!
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    (Original post by 9307914)
    The mark schemes are now online I think on the AQA website not sure about the papers
    I thought so too and they have the actual unit 4/5 etc papers but they don't have the ISA/empa papers and only have a mark scheme for task 1 of the empa
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    (Original post by PlayerBB)
    Can someone help out in e (ii) ?
    Well the ideal solvent is the one in which solute dissolves most in hot solution and doesn't dissolve in cold solution at all. Since no solution is ideal, we use the solution in which most solution dissolves most in hot solution and least in cold solution, as in the one with greatest difference in the two solubility values.
    So now in this case, the difference in values of solution 1 is 5 whereas in solution 2 is 7.5 and as solution 2's difference > solution 1's difference so 2 is a better solvent.
    Well i hope it was a helpful explanation
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    (Original post by Aimen.)
    Well the ideal solvent is the one in which solute dissolves most in hot solution and doesn't dissolve in cold solution at all. Since no solution is ideal, we use the solution in which most solution dissolves most in hot solution and least in cold solution, as in the one with greatest difference in the two solubility values.
    So now in this case, the difference in values of solution 1 is 5 whereas in solution 2 is 7.5 and as solution 2's difference > solution 1's difference so 2 is a better solvent.
    Well i hope it was a helpful explanation
    Thank you Aimen!!

    Well actually I needed (ii) not (i) but thank you for the effort of explaining it

    And I figured out part (ii) now
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    (Original post by PlayerBB)
    Thank you Aimen!!

    Well actually I needed (ii) not (i) but thank you for the effort of explaining it

    And I figured out part (ii) now
    Oops my bad :P
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    Hey, wondered if anyone could clear this up for me,

    Going over past papers for Chem6x I've come across drawing graphs for the Iodine clock reaction a few times, usually pretty straightforward, log (1/t) is plotted on the y-axis and Log(volume) on the x-axis, but I noticed in the mark scheme that says a mark is lost if the y-axis is plotted with ascending negative numbers? I'm not sure if the wording is awkward but the y-values for Log91/t) are usually negative, it doesn't seem to make sense to plot them in a descending scale (i.e. negative values getting more negative going up the y-axis),

    Cheers
 
 
 
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