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    (Original post by steph-carys)
    Wait, you got -1176?1 cause my other friend got this too! And I'm racking my brain on where I could've gone wrong... maybe something to do with signs?
    The most logical reason I can think of is that you messed up with the delta H solution? It was a low number 30 or 20 something so you could have rearranged it wrong?
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    (Original post by smartalan73)
    I got that answer too and I definitely doubled the value for hydration of K so not sure what went wrong
    I think that might be because you did lattice enthalpy= enthalpy of sol +enthalpy of hyd + enthalpy of hyd. And then rearranged. It should be LE +SOL= HYD+HYD. And then rearrange.
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    (Original post by LaraDresser)
    I know you had to use Cr3+ in your answers... it was about using Cr3+ as a reducing or oxidising agent. Are we talking about the same question?
    Yes we are... you only provide thw two possible equations which is what I said. Cr3+ cant be oxidised in system two you do know that right?Cr2+ can get oxidised in system two which is why we look at equation 6 where it had cr3+ being oxidised to 6+ but the feO4- one,7

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    (Original post by steph-carys)
    Wait, you got -1176?1 cause my other friend got this too! And I'm racking my brain on where I could've gone wrong... maybe something to do with signs?
    I can tell you what I did with letters. Ignoring negatives and using all positive numbers I did A+B-2C=D. I think A, C and D were all negative and B was positive but I just used all positive values and tried to use the diagram since the lines A and B combined seemed to make the lines C and D combined
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    Yh! You're right I don't think 6 or 7 had cr3+ in it! 🤔🤔🤔
    (Original post by LaraDresser)
    I know you had to use Cr3+ in your answers... it was about using Cr3+ as a reducing or oxidising agent. Are we talking about the same question?
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    (Original post by Haiku786)
    I think that might be because you did lattice enthalpy= enthalpy of sol +enthalpy of hyd + enthalpy of hyd. And then rearranged. It should be LE +SOL= HYD+HYD. And then rearrange.
    Yes that would be it!! I always hated the solution born haber cycles, can do the formation ones but always had a problem with these! I believe I did LE = SOL +HYD
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    (Original post by smartalan73)
    I can tell you what I did with letters. Ignoring negatives and using all positive numbers I did A+B-2C=D. I think A, C and D were all negative and B was positive but I just used all positive values and tried to use the diagram since the lines A and B combined seemed to make the lines C and D combined
    Can't quite remember what I did, I think maybe I did HYD + HYD +SOL= LE so it was probably just a sign problem? hopefully I will still get some marks
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    (Original post by steph-carys)
    Yes that would be it!! I always hated the solution born haber cycles, can do the formation ones but always had a problem with these! I believe I did LE = SOL +HYD
    and was one of them 2x hydration??
    In your diagram did you also put 2x one of the letters?
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    (Original post by smileez_101)
    and was one of them 2x hydration??
    In your diagram did you also put 2x one of the letters?
    Yes, I definitely doubled the hydration for potassium
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    (Original post by smileez_101)
    what did everyone put for the last Q when they asked for a suitable copper compound and its ionic and overall equation?
    like copper sulphate and it forms sulphuric acid and cu(hcoo)2
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    (Original post by nimoooooooo)
    Yh! You're right I don't think 6 or 7 had cr3+ in it! 🤔🤔🤔
    Yes equation 6 did. Cr2O7 2- <---> Cr3+
    obviously including the h20s and stuff

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    I have added all the grade boundaries for A/A* and calculated averages

    http://www.thestudentroom.co.uk/show...rimary_content

    bring more voters!
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    (Original post by steph-carys)
    Can't quite remember what I did, I think maybe I did HYD + HYD +SOL= LE so it was probably just a sign problem? hopefully I will still get some marks
    Yeah I just looked in the textbook and i think i get the problem, I drew that extra line with the hydrated ions on it below the line with the actual solid on it but i think it was supposed to be above it, not sure how you were supposed to know that though
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    Can't be right as H+ would appear in rate eqn
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    i put h+ is not regenerated is that enough?
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    (Original post by Jm098)
    like copper sulphate and it forms sulphuric acid and cu(hcoo)2
    lol i put Cu(OH)2 to form Cu(HCOO)2 and H2O....no idea if that counts :/
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    (Original post by smartalan73)
    Yeah I just looked in the textbook and i think i get the problem, I drew that extra line with the hydrated ions on it below the line with the actual solid on it but i think it was supposed to be above it, not sure how you were supposed to know that though
    I managed to draw my born haber cycle correctly (I think) so I have no idea why I calculated the terms in the wrong order.... again I'm gonna blame the person playing the drums next door.... pffffffftt.
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    The rate equation thing is:

    I- + H2O2 => H2O + IO-

    H+ + IO- => HIO

    HIO + I- => I2 + OH-

    OH- + H+ => H2O




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    Were there any equations or compounds (except the ionic equation on the last page) where it was necessary to put state symbols?
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    (Original post by smileez_101)
    lol i put Cu(OH)2 to form Cu(HCOO)2 and H2O....no idea if that counts :/
    So did I, it's fine because you'd be reacting an acid and an alkali, getting a salt (Cu(HCOO)2) and water.


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