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OCR A2 CHEMISTRY F324 and F325- 14th and 22nd June 2016- OFFICIAL THREAD watch

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    (Original post by alu4days)
    wasn't it to calculate pH?
    Oh yeah, perhaps. You'd still get error carried forward marks though, either way
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    (Original post by pentsr)
    was the first question Cu(NH3)6 or Cu(NH3)4?
    [Cu(NH3)4(H20)2]2+
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    (Original post by GillyTheGhillie)
    First off, one of these things didn't even come up in the paper, so I have no idea what you are talking about. Secondly, yes, you could have gotten an A in this paper without revising, some people are just naturally skilled at chemistry, or have eidetic memories, I personally did about 20 hours max revision over the entire year, the fact that this paper was incredibly easy also helps.

    Just because you either cant be bothered to revise at all, or are bad at chemistry, does not change the fact that everyone who I have talked to, including people who are bad at chemistry, found this paper easy.
    Just because you found it easy doesn't mean you should make others feel bad about not finding it as easy. That's not what this forum is for. People are meant to discuss their thoughts freely without being attacked and made to feel stupid. Just as you have done. Take some time to grow up and learn how to treat people.

    You found it easy? Good for you. Just remember others aren't the same. Just because people you know found it easy doesn't mean they represent the general student population. You must have spoke to what? 10 people max and you somehow think that's meant to represent the thousands of people. That's crazy.

    Also all three of those things did come up. Maybe you just don't remember.

    But well done on working hard and let's hope everyone did well.
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    I divided the conc by 5 then used the Kw of 60*C i think thats what you were supposed to do, a similar question came up last year 2015 paper as a 3 marker and thats what the mark scheme says to do
    (Original post by anonymous_veg)
    That's what I got however I don't think it was that simple, I think you had to use the Kw value at 60 C or whatever
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    (Original post by GillyTheGhillie)
    You see, this is my problem, it IS their fault, if you don't know the specification like the back of your hand, and then some, you HAVE NOT done enough revision, none of the calculations were complicated, nothing was off-spec, none of the questions were worded badly, this wasn't some wet and oily lap in the reasonably priced car, this was perfect conditions, it was the choice of every student whether they wanted to drive the reliant robin (not revise) or a McLaren 675LT (revise).
    I so hope you've done badly cos you've been mouthing off son
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    For the Au question i removed the CN- ions and just used the Au1+ symbol instead:

    4Au + O2 + 2H20 = 4Au+ + 4OH-Is this still OK??
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    is anyone here working on a markscheme ??
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    Paper was like a driving an open road with potholes it say 84/5 for A* like 92 for full
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    reckon 86% would be an A* ????
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    all these people saying it was easy... yeah it was but guess what? most past papers are of equal difficulty to todays, what pulls boundaries down is people making careless mistakes everywhere and never finding out about them

    everyone worried about everyone saying its easy, dont worry. u know the mistakes u made, these people dont. thats the only difference.

    im saying 74 for an A, 83 ish for A* and 90 full UMS.

    good luck in the rest of ur exams everyone
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    How about everyone just contributes with whatever they remember and we can get a markscheme going?
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    (Original post by TJB12345)
    Just going to throw out some numbers that are on my calculator and see if they ring a bell with anyone:

    2.9 x10^-2
    -1099
    104
    2.12
    3.43
    13.03
    10.68

    Anyone recognise these?
    yes!!! haha good stuff
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    (Original post by chelswaldx)
    Yeah I have a load of those numbers
    Yes all of them!Apart from for 104 I gave it to 1 decimal place.
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    (Original post by GillyTheGhillie)
    This word confused me for a second...
    Machemguy is the one.
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    did anyone else find this exam very difficult ?
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    For the cr3+ as a reducing and oxidising agent question I wrote out the equations of cr3+ with ALL of the other half cells.I didn't realise only 1 and 2,and 6 and 7 react :/
    Did anyone else do this?
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    (Original post by Ula456)
    For the cr3+ as a reducing and oxidising agent question I wrote out the equations of cr3+ with ALL of the other half cells.I didn't realise only 1 and 2,and 6 and 7 react :/
    Did anyone else do this?
    Yes, but I think it's only 2 marks lost. No negative marking right?
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    (Original post by MrZebraCookie)
    Yes, but I think it's only 2 marks lost. No negative marking right?
    Phew ok thanks!I really hope so!I thought this paper went ok but I made so many mistakes! :/
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    Personally i thought this was easy peasy, i didn't even need the personal lessons daddy got me with the head of chemistry from Eaton. I reckon i could have done it after 6 bottles of champers and still have done well enough for an A*. I see there are a few people who didnt find it so easy which is a shame for them, but oh well i'll be laughing all the way to Cambridge.
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    some answers from prev pages and some that i remembered, if wrong, please correct:
    [Cu(NH3)4(H20)2]2+
    [CuCl4]2-
    Draw the 2isomers out and trans. cis+ optical
    Empirical F CuO10H4C4 with 2- charge
    2.9 x10^-2 rate constant k
    -1099hydation entalphy
    104, Kc
    2.12
    3.43 pH
    13.03
    10.68
    X= 4
    CuCO3 ?
    Starch solution, black/ blue to colourless
    Linear
    Ag=0 goes to +1, oxidised Ois 0 goes to -2, reduced
    I2+ 2.5O2 arrow i2o5
    6OH- + 3I2 arrow 3H2O + 5I- + IO3-
    4I- + 2Cu2+ arrow I2 + 2CuI
    Cu2+ is: 1s2 2s2 2p6 3s2 3p6 3d9.
    Cu+ is: 1s2 2s2 2p6 3s2 3p6 3d10
    Ligand subwith 4Cl?
    Precipitationreaction with OH?
    HNO2eqmarrow H+ + NO2-
    Eqm movesright when OH added as makes water to replace H+
    Eqm movesleft when H+ added, as makes HNO2

    H2O2 + I- forms HIO + OH-
    H+ + OH- forms H2O
    HIO + I- forms I2 + OH- (given)
    H+ + OH- forms H2O

    or

    H2O2 + I- forms IO- + H2O
    IO- + H+ forms HIO
    HIO + I- forms I2 + OH- (given in question)
    OH- + H+ forms H2O

    For the iodine question about adding AgNO3:
    Ag + I -> AgI, [I-] decreases equilibrium 2 shifts left forming I- and I2(aq)
    [I2(aq] increases equilibrium 1 shifts left forming I2(s)
    Observations: Mixture of yellow (AgI) and grey black I2(s) precipitates is observed
    -k.russell


    The pH was given as 7 so I worked out the conc of h+ then divided kw by that to give OH-
    OH- > H+ so I put alkaline
    - maisum00

    Emf= 0.60V

    I2 is insoluble because it is non-polar and doesn't form hydrogen bonds
    Bidentate ligand donates 2 lone pairs to form 2 coordinate bonds
    Entropy increases because of more moles and solid becomes aqueous
    Drawing a cell with platinum electrode and electrons/ions marked
    -DrSerious

    H+ not catalyst because not regenerated/
    Has no impact on rate of reaction/
    It is in the overall reaction equation

    4Au + 8CN- + O2 + 2H20 = 4[Au(CN)2]- + 4OH-
 
 
 
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