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Edexcel AS Chemistry Unit 2 Thread watch

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    Yeah I flopped that pretty badly - probably lost about 20 marks at the least :teehee:. It should be about 49/80 for an A, in my opinion.
    Anyone got the paper yet? :teeth:
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    (Original post by Narik)
    Yeah I flopped that pretty badly - probably lost about 20 marks at the least :teehee:. It should be about 49/80 for an A, in my opinion.
    yeh the general consensus was that it was it was a fairly hard paper. well the multiple choice and titration bit was anyway. So going by previous boundaries i think it will be low 50's for an A. hopefully! :o:
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    By the way, you know the question where you had to draw an enthalpy profile diagram? Did you have to do anything else on it afterwards eg-if a catalyst was present?

    If so how many marks was this?
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    (Original post by deeps21)
    hmm cant remember now... but got difference of 3.5 for B and difference of 3 for A... Maybe someone else can clear that one up?

    The answer was A
    largest difference was 3.3
    the difference in B was only 3
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    what did you write for the C-f bond not breaking in the stratosphere

    I wrote because of strong bonding and stability?
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    (Original post by SK-mar)
    yeh the general consensus was that it was it was a fairly hard paper. well the multiple choice and titration bit was anyway. So going by previous boundaries i think it will be low 50's for an A. hopefully! :o:
    I found the multiple choice quite easy:yep: , but titrations was hard. Did you get something like 0.112 for the first calculation? Tbh, I'm expecting it to be bang on 50 for an A. This because the January paper was 49/80 for A. June was 51/80 for an A. So I would say this paper is between them in terms of difficulty.
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    (Original post by lpmad)
    mean titre 28x10^-3

    the conc in diluted sample was 0.112
    then conc in concentrated sample was 1.12

    then the gdm^-3 was 67.4 or something i think
    yeah mine was sumthing like that ....totally agree yaaaaa:yep:
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    Yeah I got exactly that for the titration question:
    First question = 2.8 x 10-3
    Second question = 2.8 x 10-3 (again as the number of moles were the same )
    Third question = 0.112
    Fourth question = 1.12
    Fifth question = 67.4gmol-1

    Dunno if that was right though. 67.4gmol-1 looked right.

    Okay I gotta go away and do some Biology. :facepalm:
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    (Original post by TomSouthwell)
    Aldehyde was the Primary one

    PCl5 + C4H9OH -> C4H9Cl + HCl + POCl3

    Anyone?

    yeahhh ryt ....i did that too
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    (Original post by TomSouthwell)
    Ermmm I think I put 1.) not sure tho
    are sure abt the 4) one i think it was something else cause when i read them all seemed to be true to me ??? help any one if 4th is ryt then that is the answer
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    (Original post by Narik)
    Yeah I got exactly that for the titration question:
    First question = 2.8 x 10-3
    Second question = 2.8 x 10-3 (again as the number of moles were the same )
    Third question = 0.112
    Fourth question = 1.12
    Fifth question = 67.4gmol-1

    Dunno if that was right though. 67.4gmol-1 looked right.

    Okay I gotta go away and do some Biology. :facepalm:
    ohh okz ...nice idea !! my titrations answer were also the same as yours ....and and can you tell me yours for that halogen one

    what was the one about the group 7 multiple choice which was not true?
    The options I think..
    1) They all have variable oxidation states
    2) all are acidic halides
    3) Electronegativity decreases down the group
    4) (Iodine is a stronger reducing agent than bromine??)

    i did 2 ??? accc. to me all were true??? but 4. one was something else if not then that is the incorrect one?? cause halogens are oxidising agents ... idid 2... just randomly...... what about you
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    (Original post by pervy_sage)
    The answer was A
    largest difference was 3.3
    the difference in B was only 3
    totally agree
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    For the fullerene, it was delocalised electrons, it's a mixture of hexagons and pentagons so not all the bond angles would be the same.

    Also the uncertainty in the titre was +-0.1 cm^3 because you take two readings and each reading has +-0.05cm^3

    Also i got 67.2gdm^-3 , hope that's right!
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    (Original post by bluefire)
    ohh okz ...nice idea !! my titrations answer were also the same as yours ....and and can you tell me yours for that halogen one

    what was the one about the group 7 multiple choice which was not true?
    The options I think..
    1) They all have variable oxidation states
    2) all are acidic halides
    3) Electronegativity decreases down the group
    4) (Iodine is a stronger reducing agent than bromine??)

    i did 2 ??? accc. to me all were true??? but 4. one was something else if not then that is the incorrect one?? cause halogens are oxidising agents ... idid 2... just randomly...... what about you
    I did option one because I thought fluorine never changed oxidation number...

    I seem to remember a 'scale of dominance'
    Fluorine always -1
    Hydrogen always +1
    then Oxygen aways -2

    Could be wildly wrong.
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    (Original post by srnm)
    For the fullerene, it was delocalised electrons, it's a mixture of hexagons and pentagons so not all the bond angles would be the same.

    Also the uncertainty in the titre was +-0.1 cm^3 because you take two readings and each reading has +-0.05cm^3

    Also i got 67.2gdm^-3 , hope that's right!
    apparently the question said an electron which is wrong


    not sure what Q your refering to in your second point
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    wat was the answer to the rates mcq...

    was it B (curve to constant at different levels) or D (curve to same concentration)????


    and disadvantage of using poly(ethene) packaging???
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    (Original post by dull)
    apparently the question said an electron which is wrong

    not sure what Q your refering to in your second point
    No it definitely didn't (was something like "has delocalised electrons in the structure") and none of the other options were right, bond angles wrong (hexagons, 120 but pentagons, 108), melting point was wrong (C60 sublimes at 800K, graphite has much higher ~3000K mpt) etc.

    There was a q. about uncertainty in burette, was on section B but was a multiple choice, answer was +- 0.1cm^3 in the titre because each reading (start and end) has uncertainty +-0.05cm^3
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    DHSN: Was it B or D?
    B. In equilibrium there is no requirement for the things to end up in the same concentration. D is wrong as it was a straight line to the equilibrium point.

    Regarding polythene, I went for oil. (Can't remember what the other options were though.)

    Also, i'll re-ask this: After drawing the enthalpy profile diagram, did you have to put a catalyst curve on or anything like that?
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    tOB, Nope. It didn't ask you to do that. It was asking for you to show the uncatalysed pathway and marking on what was the activation energy. which was from the reactancts to highest point of your pathway.
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    with the aldehydes, ketones...etc question can anyone remember the answer with the letter (ABCD) used??
 
 
 
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