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    (Original post by Kay Fearn)
    Damn lost two marks on the alkaline fuel cell question, couldn't work it out in time.

    Also got 35.2% for the % purity question but that's % by mass so think i lost like 4 marks from both of those^^

    i said increase in pressure increases emf because when more oh- formed/reaction speeds up not sure if that's right tho :/

    For the last 3 marks what did people say? I talked about mixing two solutions indifferent proportions one containing ligand and one containing mn04- then shine light through a filter at the solution and use data logger to measure absorbance then find ratio at max absorbance.
    - Answer about pressure is correct because it does increase emf
    - Answer about colorimetry is wrong because how does MnO4- bond with ligands??? It is not a transition metal, plus it's already a purple solution. Finally, data logger????? It's a colorimeter.

    Well done for the pressure one, I'm sorry but I think you may only get 1 mark max for your answer about the colorimeter
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    I got 50.7 for purity too
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    (Original post by K2Cr2O7)
    Formation of complex ions
    Coloured ions
    Variable oxidation states
    No 'catalytic properties'?
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    (Original post by Maki.98)
    It asked about the enthalpy change so I dont think you do it to one mole. I know the question you're talking about but that one had to specifically say 1 mole
    if you're working out enthalpy or entropy though then the units are per mole, so i divided by 2. Idk though i was unsure which to do.
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    (Original post by no-1)
    No 'catalytic properties'?
    I said that because it said cobalt and ITS COMPOUNDS
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    Did anyone out KNO3 for the acid on question?8??? I literally was thinking it could be any so just went with that but now I'm writing this I realise it could've formed KMno4- so


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    (Original post by hi-zen-berg)
    For increase O2 pressure I put decrease EMF?

    because Ecell=Ered-Eox

    Reduction EQM would shift to left to oppose change, decreasing Ered, therefore decreasing Ecell?
    i put this as well
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    (Original post by minjinoor)
    what do you think grade boundaries will be?????
    I genuinely don't know. I find chem5 easier than chem4. If I was estimating:

    67/68 - B
    76/78 - A
    83/85 - A*
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    (Original post by no-1)
    No 'catalytic properties'?
    Yes thats the 4th one.
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    (Original post by no-1)
    No 'catalytic properties'?
    Yes, catalytic properties would also be on the mark scheme.
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    (Original post by hi-zen-berg)
    For increase O2 pressure I put decrease EMF?

    because Ecell=Ered-Eox

    Reduction EQM would shift to left to oppose change, decreasing Ered, therefore decreasing Ecell?
    I wrote this too, but everybody saying it was increased


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    (Original post by hollyclaireee)
    Did you write the units of deltaG as Jmol-1? If you did then you should get all the marks I think!

    Then if you did deltaS divided by 1000 instead you'd have to give units of deltaG to be kJmol-1 right?
    I think I wrote my units as JK-1mol-1 because that's what delta s was given in? Can't really remember though.
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    (Original post by randoms132)
    [Cr(h20)3(oh)3](s)


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    So X(g) = CO2 ?
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    How many marks do you lose for not converting degrees to k?
    • Welcome Squad
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    Welcome Squad
    (Original post by 26december)
    I put H+ too but I don't think so because H+ isn't a reagent... So annoying


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    What was the question asking for HCL?
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    (Original post by Suits101)
    Did you say catalyst for last quesiton was Mn2+ and tick H2SO4?
    Yes
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    (Original post by OloMed)
    So X(g) = CO2 ?
    Yes, i think it is.
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    lol and i the only idiot that got 49.3 for the percentage purity
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    (Original post by Spectral)
    - Answer about pressure is correct because it does increase emf
    - Answer about colorimetry is wrong because how does MnO4- bond with ligands??? It is not a transition metal, plus it's already a purple solution. Finally, data logger????? It's a colorimeter.

    Well done for the pressure one, I'm sorry but I think you may only get 1 mark max for your answer about the colorimeter
    Ahh not too bad then, I think i lost like 10 marks max on that paper including any silly mistakes I might have done so happy with the outcome

    I just hoped anything on calorimetry or spectrometry wouldn't come up because I never learned them fully but 3 marks isn't too bad.
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    (Original post by Suits101)
    It said use your answer from the question above.

    The answer was negative, hence the forward reaction is exothermic.

    This same question (but with a different compound) came up in a previous paper.



    -65.1 (divide it by 2 because it's standard meaning one mole, not two as question gave)
    delta G got -65.1
 
 
 
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