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    (Original post by intellectual1)
    Are people doing an all nighter here?
    i have had a lot of exams so i think im gonna stay up gor a while still maybe another couple of hours, besides i dont really get much sleep before an exam, got such bad nerves. im just dreading the synopsisity bit of it, u planning an all nighter?
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    (Original post by gradu)
    Maybe me!

    Going through Jan 2011 paper as i type this, not a bad paper... I get most of it, and am checking through text and mark scheme for what OCR penalise.

    I have a few past papers i'll take tomorrow morning to do in the Library

    EXAM IS AT 13.00 yeah? Just checking
    yeah it is...for some reason my brain does'nt want to switch off just yet...having difficult sleeping right now..also know i'm going to lose marks on C3 because of devoting more time to F325 ahhh C4 will be a higher score than C3 no doubt! If only they put a day between those papers!?

    Jan11 is how all papers from now on are going to be...Specimen and Jun10 are not really that relevant...since it is all about the application of knowledge in novel contexts
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    HI, please can someone tell me a good answer for if/when they ask about enthalpy of hydation, small, highly charged ions have higher charge density but WHY does this make hydation more exothermic??
    please THANKS!!
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    (Original post by Reccoshai)
    i have had a lot of exams so i think im gonna stay up gor a while still maybe another couple of hours, besides i dont really get much sleep before an exam, got such bad nerves. im just dreading the synopsisity bit of it, u planning an all nighter?
    i intend to sleep for few hours, i usually sleep 2-3 hours and then have a few proplus and energy drinks and keeps me wide awake and alert...

    i shall be flooding this thread with some of my notes later on... hmm

    Enthalpy of Neutralisation has come up in Jan11

    Enthalpy of Hydration has'nt yet?

    Buffers and uses

    pH in blood

    Entropy Free Energy is relatively new to the OCR specification..

    Oxidation numbers - examiners love testing these for some reason hmmmm and candidates still struggle with them so there's a good chance we'll have to encounter Oxidation numbers of ions and/or complexes etc

    Electrodes - concentration effect...

    Fuel Cells - possible question perhaps?

    Electronic configuration of Transition Elements - very common question in past questions and on other boards as well

    Precipitation reactions Fe and Cu always seem to feature hmmm

    Redox calculation
    - sure thing...examiners love these...always is a question...
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    (Original post by mazam)
    I think thats wrong.
    You never include h20 in kstab .. just like in ka .
    Also its double brackets around the other 2.
    You are correct, a terrible typo and lack of concentration on my behalf. Water is never present in K stab. Good luck with your exam!
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    (Original post by gradu)
    Maybe me!

    Going through Jan 2011 paper as i type this, not a bad paper... I get most of it, and am checking through text and mark scheme for what OCR penalise.

    I have a few past papers i'll take tomorrow morning to do in the Library

    EXAM IS AT 13.00 yeah? Just checking
    (Original post by intellectual1)
    yeah it is...for some reason my brain does'nt want to switch off just yet...having difficult sleeping right now..also know i'm going to lose marks on C3 because of devoting more time to F325 ahhh C4 will be a higher score than C3 no doubt! If only they put a day between those papers!?

    Jan11 is how all papers from now on are going to be...Specimen and Jun10 are not really that relevant...since it is all about the application of knowledge in novel contexts
    I had a Bio exam yesterday which was dreadful (the exam content was barely related to what the text book was teaching, more of a paper people from Countryfile would've put together ... :/ )

    Ooo, good luck in them, sounds like u got a few hectic days pal!

    If the paper tomorrow is like this Jan 2011 paper (On question 6 at the moment) I should actually be fine :| just need to keep an eye on units they chuck inn!! I lack confidence in the exam, always question myself even when I know what i am doing is correct!!

    On the bright side, i'll treat myself to a chinese takeaway box for lunch at 12.30
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    (Original post by njordan11)
    HI, please can someone tell me a good answer for if/when they ask about enthalpy of hydation, small, highly charged ions have higher charge density but WHY does this make hydation more exothermic??
    please THANKS!!
    Because hydration is the ability to attract/bond with water molecules. Smaller ions/greater charged ions exert greater forces of attraction on water molecules and hence it's more exothermic, more energy is released when forming stronger bonds.
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    Can someone help me please with this:
    The presence of nitrate(III) ions, NO2
    –, interferes with this method because NO2 ions can also oxidise iodide ions to iodine.
    (ii) Write an equation for the oxidation of aqueous iodide ions by aqueous nitrate(III) ions.
    Hydroxide ions are produced in this reaction.
    How would you start?
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    (Original post by njordan11)
    HI, please can someone tell me a good answer for if/when they ask about enthalpy of hydation, small, highly charged ions have higher charge density but WHY does this make hydation more exothermic??
    please THANKS!!
    It makes the hydration more exothermic because they attract h20 molecules more strongly when they're floating around in solution, as you say, due to higher charge density
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    (Original post by hey-hey-hey)
    Can someone help me please with this:
    The presence of nitrate(III) ions, NO2
    –, interferes with this method because NO2 ions can also oxidise iodide ions to iodine.
    (ii) Write an equation for the oxidation of aqueous iodide ions by aqueous nitrate(III) ions.
    Hydroxide ions are produced in this reaction.
    How would you start?
    I'd begin by writing down all of the reactants/products that you're given in the question, aside from any hydroxide ions, protons or H20 that you may well need to even things up - so, begin with saying that N02 + I- goes to I2 + NO
    Then, you need to work out which of these atoms change oxidation number, and balance those atmos that do (so, I goes from -1 to 0 so balance the number of iodines). That should set you on your way
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    What are the half equations for 4Fe2+ + O2 + 4H+ ---> 4Fe3+ + 2H2O ?

    & could anybody please tell me the bond angles for each shapes?
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    Any tips on how to work out 2 step reactions from rate equation. I nearly always get them wrong.
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    I'm going to go to bed and hopefully read over my notes and redo another past paper before the afternoon.

    Good luck everyone
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    WheN you guys going to sleep???
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    (Original post by Student21)
    Any tips on how to work out 2 step reactions from rate equation. I nearly always get them wrong.
    The rate equation gives you the reactants and the molar quantities (look at the power of each reactant concentrations) involved in one step (the rate - determining step) of the reaction. I don't think there's any specific rule that it has to be the first step but I think it's decent practice to put it down as the first.
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    Has the mark scheme for the jan 2011 paper been posted by any chance? :P
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    (Original post by apo1324)
    Has the mark scheme for the jan 2011 paper been posted by any chance? :P
    http://www.scribd.com/doc/57286393/O...11-Mark-Scheme
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    (Original post by goldlock)
    If Y is in excess I take it you mean that 4 moles of Y is in excess, so focus on using the moles of x - if it takes 3 moles of x to make 2 moles of water, then it takes 1.5 moles of x to make 1 moles of water - so you divide your q value by 1.5 instead of dividing it by 3

    thank you soo much ive been stressin about this for the last 3 months lool

    you seem to know you're stuff so i hope you dont mind if i ask a few more questions :P

    1) buffer systems --- HOW TO REMEMBER AND ANSWER TO GET MAXIMUM MARKS ?

    2) IN MANUFACTURE OF CaC2 what is the maximum mass of CaC2 that can be obtained from 40.0kg of Ca0 and 4kg of CO?

    CaO+ 3C------> CaC2 + CO


    sorry if im pushing my luck :P

    thank you
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    Thank you very much.
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    beware people there going to ask us

    "a hedgehog produces a stereoisomer, and its gas has a conc of 0.0009 mol dm-3

    work out the volume of poo it produces and the colour of the complex ion"

    hahaahahaha credit goes to sportycricketer :p:
 
 
 
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