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    In born haver cycle, would you use atomisation or sublimation
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    (Original post by Jessica-F)
    Does anyone have notes or know a good site where i can get help with the calculations? i get really confused with some of them.

    http://www.thestudentroom.co.uk/show....php?t=1288539
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    (Original post by Puffy14)
    How did you get the chromium one? Can you please write the half equations for that one?
    Reduction half equation
    Cr_{2}O_{7}^{2-} + 14H^{+} + 6e^{-} --> 2Cr^{3+} + 7H_{2}O

    Oxidation half equation
    Fe^{2+} --> Fe^{3+} + e^{-}

    Need to multiple the oxidation reaction by 6 to cancel out the electrons.

    Therefore:
    Overall equation:
    6Fe^{2+} + Cr_{2}O_{7}^{2-} + 14H^{+} --> 6Fe^{3+} + 2Cr^{3+} + 7H_{2}O
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    Can anyone help me with this question?

    On June 2011 paper, Qa)i) The bond enthalpy one, i don't how the mark scheme says -38?
    Bonds broken - Bonds made, when i did it it came out as -76
    In the mark cheme they have divided the N2 bond enthalpy by 2 and multiplied the H2 bond enthalpy by 3/2?? Why??

    ANYONE?
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    (Original post by marleyxd)
    Can anyone help me with this question?

    On June 2011 paper, Qa)i) The bond enthalpy one, i don't how the mark scheme says -38?
    Bonds broken - Bonds made, when i did it it came out as -76
    In the mark cheme they have divided the N2 bond enthalpy by 2 and multiplied the H2 bond enthalpy by 3/2?? Why??

    ANYONE?
    It says the formation of one mole of ammonia, hence 1/2 N2 + 3/2 H2 --> NH3.
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    (Original post by marleyxd)
    Can anyone help me with this question?

    On June 2011 paper, Qa)i) The bond enthalpy one, i don't how the mark scheme says -38?
    Bonds broken - Bonds made, when i did it it came out as -76
    In the mark cheme they have divided the N2 bond enthalpy by 2 and multiplied the H2 bond enthalpy by 3/2?? Why??

    ANYONE?
    the definition of enthalpy of formation is:

    the enthalpy change that occurs when 1 mol of a molecule is formed from its constituent elements when they're in their standard states, under standard conditions.

    In the question it forms 2 moles so you need to use it to find 1 mol formation
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    Did anyone else find the June 2012 past paper really difficult??
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    (Original post by jqian)
    It says the formation of one mole of ammonia, hence 1/2 N2 + 3/2 H2 --> NH3.
    Thanks! I never read questions properly....
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    jan 2013 is one nasty paper....personally if you can ace the jan 13 paper, I think you'll be fine for the exam tomaz!
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    In a b-h cycle, when you start off with cl2, how to I get this to just cl so it can be ionised. Do I double half whattt
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    (Original post by sikhtank27)
    jan 2013 is one nasty paper....personally if you can ace the jan 13 paper, I think you'll be fine for the exam tomaz!
    where'd you get the jan 13 from?
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    (Original post by problematic)
    Hey guys can anyone help me out with this question about cell representations, It's from the Jan10 paper

    I find it kind of confusing how the did it in the mark scheme and if someone could talk me through it that would be great

    I've attached the pic with the q

    Thanks in advance
    it just means the cell notation x
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    For those who have finished all the papers, what type of revision are you doing?
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    What colour is Co(H2O)3(OH)3 after it has been oxidised. In one book it says 'beige' in another it says 'brown' ??
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    (Original post by flyylikejetz)
    What colour is Co(H2O)3(OH)3 after it has been oxidised. In one book it says 'beige' in another it says 'brown' ??
    Mark schemes usually say dark brown I think
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    (Original post by SexyAndIKnowIt.)
    In a b-h cycle, when you start off with cl2, how to I get this to just cl so it can be ionised. Do I double half whattt
    when you do the enthalpy of atomisation for Chlorine this should take it from Cl2 to 2 Cl, then when you come to electron affinity you multiply this by 2.

    Hope this makes sense
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    chocolate brown -

    thats how I remember it .. just go for brown - I highly doubt that will come up anyway
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    I hope tomorrows paper is nicer than the biol5 one we had yesterday...
    then again I'm sure it will be as chemistry > biology
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    (Original post by Chris-69)
    For those who have finished all the papers, what type of revision are you doing?
    I'm going through all the papers again not sure how much good it's doing though since I subconsciously know the answers, other than that I'm reading the AQA book and copying out all of the periodicity, catalyst and transition equations over and over again! :facepalm:
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    (Original post by mulac1)
    I hope tomorrows paper is nicer than the biol5 one we had yesterday...
    then again I'm sure it will be as chemistry > biology
    I don't want to jinx anything but I don't thinks its possible for it to be worse than the biol5 exam

    Things can only get better
 
 
 
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