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    (Original post by chemchemchem123)
    This paper was hard - but not impossible. Its going to define between the people who really know their chemistry and worked very hard to deserve an A star. The buffer question was hard - but then again if they were to give us any other buffer question it would have been far too easy. There was a question like this on one of the old OCR past papers.
    Maybe theres point in complaining.. but probably not. I think it should be around 75% for an A, 85% for an A*.
    I got some things wrong, I know I definitely lost about 10 marks - the erest will have just been minor errors.
    And on the plus side - it was much easier than Biology F215 on Monday!
    I disagree about the grade boundaries. For June 2010 it was 81% for an A* and 71% for an A. This was harder than June 2010 so I think the grade boundaries will be lower than that.
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    (Original post by 786girl)
    for the last question i just worked out the moles of that thingg and divided it by 2 (total guess) then got a percentage of like 13%... haha
    omg i cant believe i am laughing my future depended on thiss exam it was horrible!!!!!!!!!!!!!!!!!!
    i almost burst out crying in the exam i dont know what to do or say im so so so so guttted

    what did u guys get for the complex ions?

    when it was substitued by hcl was it ni(cl)4?

    Yes it is (NI(Cl)4)2-
    because it says 4 coordinations bonds
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    (Original post by Kalamari Dave)
    Guys lets make the Unofficial Mark Scheme Mk1
    Please say if you have things to add, modify, or correct (theres lots!)

    ?)definition of lattice enthalpy: Energy given out when one mole of an ionic compound is formed from its constituent gaseous ions.[2]
    ?)Why is hydration enthalpy for Cl- exothermic? Bonds formed with deltaH+ on water molecules, heat given out.
    ?)Born Haber diagram of Enthalpy of solution, hydration, lattice enthalpy. 4 stages, incomplete answers: Mg2+(g) + 2Cl-(aq), Mg2+(aq) + 2Cl-(aq) [2]
    ?)
    ?
    ?)
    ?)
    ?)Magic tang question: use lactic acid because its pKa is close to our desired pH (within one unit), so it buffers better. I used henderson hasselbach equation, pKa = pH + log [A-]/[HA] or you can use the ka expression to work out [A-]/[HA], which (I got) ~0.49
    I think it will be tangy because the buffering range (+/- 1 pH unit of pKa) certainly ecompasses the tangy pH of 3.55
    would it make a difference if in the born haber you put the two hydration enthalpies the other way round?
    also, what happened if you picked another buffer for the tangy question?
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    (Original post by PedalBrain)
    Did anybody get a KC value of 45?? I deem this one of the easier questions but still, they managed to make ever the simplest of topics within the unit tricky. I can understand you make some things hard and some easier, but literally everything in the paper required more than the average time to think about it. If you have to read so much b****x about 'sweets' and fictitious material then the time allocated should increase. It seems the time taken to read each question has significantly increased, meaning less time to solve them... Does that make sense or am I the only one who believes so??
    Yea it's totally retarded the ammount of irrelevant stuff they expect you to read for like a 2 mark question that has very little to do with what they write down.

    I thought as a whole it was reasonable time wise though, especially compared to unit 4 in january, but I did skip out some of the tedious 1/2 markers

    My kc was 22.5 which is half of what you got...

    Did you divide each no. of mol by 2 to get the concentration since it was in 2 dm^3 volume?
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    (Original post by PedalBrain)
    Did anybody get a KC value of 45?? I deem this one of the easier questions but still, they managed to make ever the simplest of topics within the unit tricky. I can understand you make some things hard and some easier, but literally everything in the paper required more than the average time to think about it. If you have to read so much b****x about 'sweets' and fictitious material then the time allocated should increase. It seems the time taken to read each question has significantly increased, meaning less time to solve them... Does that make sense or am I the only one who believes so??
    Yes that was what I got so I hope it's right.
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    what did you guys think of the grade boundary ?
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    (Original post by Student21)
    I'm in the same boat as you. I dont think i've even got an Eand i tried so hard in revision but my mind went blank in the exam.

    (Original post by Medifield)
    I think I've failed... I can't face my family and tell them. I really don't know what to do same

    w.
    i am inda same boat, they have high expectations of me and luk wots happenning. i couldnt answer half da paper, hardly knew nything, gona get a U grade
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    WTF was this exam?!?!?!
    Im supposed to get an A in this and the smartest girl in our class had no clue what was going on in that paper!!!!
    If we would have had more time, I probably could of done the questions because they required alot of thinking before writing things down!
    I thought OCR was better than AQA but I was wrong.
    Hate this Board.
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    (Original post by Rickesh)
    If they want to show an constant half life why not do it PROPERLY instead of doing averages!!!? goshh! so annoying....because most people would think that would be a second order no?
    I think it was because it was meant to show experimental data, there were a few results that didn't fit the curve so the curve may not be exactly where it should of been...
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    (Original post by woods.vanessa)
    Im supposed to get an A in this and the smartest girl in our class had no clue what was going on in that paper!!!!
    how big is your ego?

    no hedgehog questions or seaweed eating sheep today though....
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    yes i have got 45s-1 does any one get this ?
    i got the rate as 0.094 moldm^-3s^-1
    then i divided the rate by concentration which was 0.01 moldm^-3
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    (Original post by terry_2006)
    what did you guys think of the grade boundary ?
    I reckon 67% for an A and 76% for an A*.
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    (Original post by Limesasquatch)
    noooo! dont say that! its right its definitely probably right!
    yeah man I got that too. So let's assume it is right then
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    (Original post by Student21)
    I's sorry but i worked EXTREMELY hard. Is going through the spec 4 times not enough? Reading every page of the unit at least 5 times not enough? I really sat my ass down this year to get into uni and thanks to OCR im not going to anymore.

    Well I'm sure seeing as everyone else found it so hard the grade boundaries wont be very high, but I went through the spec many a time, did every practice question I could get my hands on, read over and above the syllabus where the stretch and challenge points were marked in the book - and it went okay.
    I do agree that OCR are ridiculous and the papers have no way of preparing for, the text books are insufficient, and the topics that they cover in their papers aren't reflective of the whole syllabus! I also thought Chemistry was a guaranteed A* for me - now I'm thinking high A.

    Polymers, chains etc. next week is only going to be worse!

    OCR are going to have to make the grade boundaries low by the sounds of it though- otherwise no one will get into uni and the universities will have no one to pay their high fees! By the sounds of it a lot of med students aren't going to make their grades
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    Wow what a ridiculous exam, perhaps the hardest Ive ever had to battle through.

    I need 87 UMS marks to get onto my Chem eng Degree. How many proper marks will this be?
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    Unit 4 January was rushed but it fairly defined between the people who knew the material well and didnt (me being one who didnt). This however I believe in the allocated time I could apply what I knew to the extent of doing very well. However, to many factors made the exam noticeably unfair, in my opinion, no A2 exam should be easy, but none should be irrational...
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    (Original post by good morning)
    how big is your ego?
    What are you talking about??
    I said Im predicted an A but in I definitely WONT get one!
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    (Original post by Rickesh)
    I got 33.8% but I think that's wrong
    I got 33.8% as well
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    (Original post by Limesasquatch)
    I put order 1 just because it was only a line of best fit, many points were not on the line
    Though to be fair, 10s in 200 is only 5% - that's still really quite close to a line for a chemistry experiment! Clearly it was intended to be a constant half life.
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    (Original post by Richrr)
    Wow what a ridiculous exam, perhaps the hardest Ive ever had to battle through.

    I need 87 UMS marks to get onto my Chem eng Degree. How many proper marks will this be?
    Probably around 50 marks or so
 
 
 
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