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    Part 2 of the mock tomorrow, which is basically everything except transition metals. Should do alright, just going over the periodicity equations and some of the redox stuff. My mum scared me today telling me it's 4 weeks on Friday till my birthday party which means 4 weeks Wednesday till the exam :eek3:
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    (Original post by Minnie me)
    Hi,
    They should be attached
    Me
    thank youuuuuuuuuuuuuu!!!
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    Could someone please answer a few queries I have about jan 2010 chem5 paper

    1. Question 4a - I don't understand how the bond enthalpy has been calculated and why it's been calculated that way.
    2. This is more a clarification - the first EA is exothermic as there's strong attractions between the positive nucleus and electron being added and the second EA is endothermic as energy is required to overcome the repulsion between the negative ion and the electron being added, right?
    3. Question 5e(iii) so is a reaction not feasible is it's above the temp you calculate when Gibbs energy = 0?

    http://filestore.aqa.org.uk/subjects...W-QP-JAN10.PDF
    http://filestore.aqa.org.uk/subjects...W-MS-JAN10.PDF

    Thanks
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    Can anyone shed some light on these questions;
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    Its the reaction 2 im confused about. To get its to a dark brokwn solution gotta be oxidised. Right...but then somthing must be reduced...hence oxygen...but what too??? In the ms it aays reduced to OH-...but cannot you not right too water????


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    How in the world do we know that line represent entropy???

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    (Original post by Dalts)
    Well don't forget that alkaline conditions favours oxidation and acidic favours reduction, and we're oxidising the ligand complex, however the method with hydrogen and water is accepted in the MS


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    Well according to that then because ligand oxidised it favours alkaline conditions...but then should the O2 not go to water instead of the OH-???

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    (Original post by DoctorWannaBe101)

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    How in the world do we know that line represent entropy???

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    The Equation is ΔG=ΔH-tΔS

    Which can be written as ΔG= -tΔS+ΔH
    Equation of a straight line: y= xm +C

    The graphs shows that the Y axis is ΔG
    X axis is t
    The Y intercept will be ΔH
    m, the gradient will therefore be -ΔS.

    Do you take maths or physics by any chance?
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    (Original post by DoctorWannaBe101)


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    How in the world do we know that line represent entropy???

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    When I did this question I remember thinking the exact same thing. But I think one of the other parts of that question asked what the units would be? And it was kJ K-1 mol-1 or something and I just figured that this was the unit for entropy (more usually written as J K-1 mol-1 but you can use kJ too). But it is a slightly obscure question.
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    (Original post by Vip3rgt9)
    The Equation is ΔG=ΔH-tΔSWhich can be written as ΔG= -tΔS+ΔHEquation of a straight line: y= xm +CThe graphs shows that the Y axis is ΔG X axis is t The Y intercept will be ΔH m, the gradient will therefore be -ΔS.Do you take maths or physics by any chance?
    Thanks for this! And nope I don't. That's the worst questions every!
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    (Original post by TLi1295)
    When I did this question I remember thinking the exact same thing. But I think one of the other parts of that question asked what the units would be? And it was kJ K-1 mol-1 or something and I just figured that this was the unit for entropy (more usually written as J K-1 mol-1 but you can use kJ too). But it is a slightly obscure question.
    Very obscure, but thanks!Very obscure! But thanks!
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    Hi
    I was just wondering if anyone knows if we need to know the colours of vanadium ions (pg220 in textbook) for this exam?
    Thanks
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    Does anyone have Jan/June 2009 past paper?
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    (Original post by hawraaj313)
    Does anyone have Jan/June 2009 past paper?
    Yeah will upload later unless anyone does in the meantime :-)
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    Hello, pls can someone clarify this question for me?

    When they ask us to work out enthaply change, entropy change etc we always get things into the form so that there is only 1 mole of the product formed , right? But what do we do if there is more than one product?
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    (Original post by TLi1295)
    When I did this question I remember thinking the exact same thing. But I think one of the other parts of that question asked what the units would be? And it was kJ K-1 mol-1 or something and I just figured that this was the unit for entropy (more usually written as J K-1 mol-1 but you can use kJ too). But it is a slightly obscure question.
    Hello , you know by definition , the enthalpy of formation is 1 mol of the compund from its elements? then how do we write the equation if there is more than one product involved? thanks for all help offered! thanks once again!
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    (Original post by laurawoods)
    Hello , you know by definition , the enthalpy of formation is 1 mol of the compund from its elements? then how do we write the equation if there is more than one product involved? thanks for all help offered! thanks once again!
    Like you said the enthalpy of formation is 1 mole of a compound formed so there should only be one product produced for that enthalpy of formation. If you're talking about using enthalpy of formation data and there is more than one product in the overall equation then you would use the enthalpies of formation for both products. So I think there would be two equations? One for the formation of one product, another for the formation of the other product. Sorry if that doesn't make sense ... :P
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    Hey guys does anyone if we need to know the colours of the tetrachloride complexes for this exam?
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    (Original post by Emzy94)
    Hey guys does anyone if we need to know the colours of the tetrachloride complexes for this exam?
    Yep..Cocl4 and cucl4

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    on question 7b on june 2012, it says the complex [cu(H2O)3(OH)3] is green, but I thought it was grey-green? It doesn't mention that anywhere in the markscheme?
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    (Original post by dizzy17)
    on question 7b on june 2012, it says the complex [cu(H2O)3(OH)3] is green, but I thought it was grey-green? It doesn't mention that anywhere in the markscheme?
    I have never ever seen this complex before. It doesnt make sense. are you sure that is the formula?

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    (Original post by dizzy17)
    on question 7b on june 2012, it says the complex [cu(H2O)3(OH)3] is green, but I thought it was grey-green? It doesn't mention that anywhere in the markscheme?
    You haven't read the question correctly, its asking for [Cr(h20)6]+3 with OH- drop wise until XS so, it will produce a green ppte and then dissolve in XS to produce a green solution, I'm sure you can work out the equation from this
 
 
 
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