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    (Original post by andersson)
    Haha, I mean like perfected! Not just skimmed over
    30 minutes then.
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    (Original post by andersson)
    Haha, I mean like perfected! Not just skimmed over
    Do you mean taking notes or doing questions or what? I would have though you could revise the whole course in that time.
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    Please please please can someone explain to me the section on chlorine radicals!!
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    (Original post by Puffin111)
    Please please please can someone explain to me the section on chlorine radicals!!
    UV breaks CCl(2)Fl(2) into CClFl(2) and Cl ¤

    Cl¤ + O(3) ---> ClO¤ + O(2)
    ClO¤ + O(3) ---> 2O(2) + Cl¤

    And it keeps breaking it yp
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    (Original post by L'Evil Fish)
    UV breaks CCl(2)Fl(2) into CClFl(2) and Cl ¤

    Cl¤ + O(3) ---> ClO¤ + O(2)
    ClO¤ + O(3) ---> 2O(2) + Cl¤

    And it keeps breaking it yp
    My book is different it says

    Cl¤ + O(3) ---> ClO¤ + O(2)

    ClO¤ + O¤ ---> Cl¤ + O(2)

    I assume both are correct? but wanted to check that one isn't definitely wrong
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    (Original post by BP_Tranquility)
    True, but nobody's actually say the specimen exam and its initial purpose was to provide schools with an idea on how the exam would be set out...in our exam, they probably will take into account the different answers (although my chemistry teacher emailed OCR regarding this and they said it doesn't matter apparently)...


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    Oh right thanks :P grrr OCR's specimens always annoy me > unluckily all my A-levels are going to be OCR....
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    (Original post by NatashaG)
    My book is different it says

    Cl¤ + O(3) ---> ClO¤ + O(2)

    ClO¤ + O¤ ---> Cl¤ + O(2)

    I assume both are correct? but wanted to check that one isn't definitely wrong
    either one is correct since the chlorine radical is left at the end of each reaction...so the chain reaction continues

    Ryan
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    (Original post by NatashaG)
    My book is different it says

    Cl¤ + O(3) ---> ClO¤ + O(2)

    ClO¤ + O¤ ---> Cl¤ + O(2)

    I assume both are correct? but wanted to check that one isn't definitely wrong
    I'd go with L'Evil's because the chlorine oxide is more likely to react with ozone than an oxygen radical because the stratosphere is full of ozone.
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    Thanks! So if that was to come up as a 6 marker what kind of stuff would you be expected to write?
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    I've just done the specimen and I noticed that quite a few questions were taken from the old specification past papers..


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    Does anyone know previous grade boundaries for C4,C5,C6 exam, because I cannot find them for previous years only for C1,C2,C3 ?
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    (Original post by carns)
    Does anyone know previous grade boundaries for C4,C5,C6 exam, because I cannot find them for previous years only for C1,C2,C3 ?
    I think that's because this is the first year of the new specification to do the C4 C5 C6 exam
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    How do we know which is the endothermic/exothermic direction of an equilibrium reaction?

    Or does it just tell you?
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    (Original post by cameron262)
    How do we know which is the endothermic/exothermic direction of an equilibrium reaction?

    Or does it just tell you?
    It tells you. Have a look at the 6 marker for C5 in the specimen paper.
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    (Original post by cameron262)
    How do we know which is the endothermic/exothermic direction of an equilibrium reaction?

    Or does it just tell you?
    Exothermic is a bond making process.
    Endothermic is bond breaking process.

    2SO2 +O2 ->2SO3

    The arrow is supposed to be reversible, so it's an equilibrium mixture.

    The arrow that goes to the right is exothermic (since bonds are created as SO2 and O2 react, "joining" up these molecules to give SO3).

    The arrow that would go to the left is endothermic (as the bonds in sulfur trioxide are broken, "splitting" the SO3 molecule to give back SO2 and SO3).

    Hope this helps
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    (Original post by Red Fox)
    Do you mean taking notes or doing questions or what? I would have though you could revise the whole course in that time.
    I mean doing the CGP question booklet too, I'm a third through it now.
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    If a six mark question came up on Chlorine radicals, there isn't exactly 6 things to write? There are literally 3 / 2 stages and 1 mark for good english = 4 marks tops :/
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    (Original post by dazzer19)
    If a six mark question came up on Chlorine radicals, there isn't exactly 6 things to write? There are literally 3 / 2 stages and 1 mark for good english = 4 marks tops :/
    You could talk about why CFCs were used in the first place, they take a long time to break down, write down the equations, how to ozone protects us from UV rays, and replacements (e.g. HFCs)...
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    (Original post by dazzer19)
    If a six mark question came up on Chlorine radicals, there isn't exactly 6 things to write? There are literally 3 / 2 stages and 1 mark for good english = 4 marks tops :/
    6 mark question are not about writing 6 things, if u look at mark schemes it tells stuff like full understanding, or writing an equation and discussing other things. Its about showing a detailed scientific overview of the topic. +decent spelling ect
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    how do you work out mass of salt/sodium and RDA/GDA percentage mass questions?!
 
 
 
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