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    Does anyone have any idea what the bondaries will be for the CHEM4 paper? I was just wondering since chem5 will seem to be a bit higher
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    (Original post by SirRaza97)
    Does anyone have any idea what the bondaries will be for the CHEM4 paper? I was just wondering since chem5 will seem to be a bit higher
    My guesses:

    CHEM4:
    120 UMS = 88/100
    108 UMS = 81/100
    A = 74/100

    CHEM5:
    120 UMS = 93/100
    108 UMS = 85/100
    A = 77/100

    But this is of course just guesswork - I'm usually quite accurate though!
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    (Original post by Humza Ali)
    what was the answer for the platinum electrode question guys? did it have any effect?
    Surface area of electrode: No effect.
    Increased oxygen pressure: Higher emf.
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    I think I got around 80-82 on this paper. Do you think that will be an A?
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    (Original post by Aethrell)
    Still don't get why increasing the pressure of the oxygen would make a difference... surely they're not all gaseous so it wouldn't make a difference?
    When you're measuring E0 it must be under standard conditions else it will change (so 100kPa) so increasing the pressure will make a difference purely becuse it's no longer under standard conditions
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    Wasnt lattice dissociation enthalpy negative not positive?
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    Could you put equlibrium signs in the contact process equations? Would I drop the marks with even with the equations I put correct?
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    Name:  ImageUploadedByStudent Room1466678805.052507.jpg
Views: 475
Size:  53.9 KB Grade boundaries should be high according to my Twitter poll.


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    (Original post by Bigboss27)
    Wasnt lattice dissociation enthalpy negative not positive?
    The arrow on the diagram went the wrong way so you had to change the sign to get a positive. Also it doesn't really make sense if you're breaking up a lattice that it would give out energy.
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    (Original post by emilies18)
    I think I got around 80-82 on this paper. Do you think that will be an A?
    Most likely. The paper was similar in difficulty to last year and you only needed 76 for an A


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    (Original post by Medlad101)
    **** i did the same
    its probably fine. They didn't ask us to clearly show the type of bonding in the complex.
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    Can someone help me out with a few Qs- for the one about environment , can you just put h20 only product or do you have to hammer on about it not being as bad as co2? Also on the Q (7 marks) about adding ethanediol te to co2+ do you have to say delta H is the same ?:/ also the very last Q - can you say: mn04- absorb white light frequencies and the freq not absorbed detected by colouring ter to give value of conc
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    would it be ok to put + aq on the reactants side of the enthalpy of solution equation? or will it just say ignore +aq on the mark scheme?
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    has anyone done a chem 4 unofficial markscheme?
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    For the percentage purity I put two calculations one for C2O4 and one for Fe on an extra sheet ,I didn't cross any out ,do I get a few marks or not ???

    Thank you
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    does anyone have pictures of the paper? would be much appreciated xoxo
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    What did people put for why aren't large lumps of pt used? (something like that)
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    (Original post by Sloth45)
    Why would excess conc. NH3 not be accepted though - surely that just makes [Cr(NH3)6]3+ which is a green solution?
    That's purple - nh3 can be used to make cr(oh)3(h20)3 but not the cr(oh)6- - as excess Nh3 forms purple soloution


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    50.7% Officially the percentage purity not 94%
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    (Original post by FireBLue97)
    50.7% Officially the percentage purity not 94%
    You know you're wrong right?


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