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Edexcel - Chemistry Unit 2 - 4 June 2013 watch

  • View Poll Results: Which topic(s) are you finding most difficult?
    Shapes of molecules and ions
    11.66%
    Intermediate bonding and bond polarity
    15.95%
    Intermolecular forces
    9.82%
    Redox
    17.79%
    Group 2 & 7
    40.49%
    Kinetics & Equilibria
    14.11%
    Organic Chemistry - Alcohols and Halogenoalkanes
    39.26%
    Mechanisms
    26.38%
    Green Chemistry
    28.83%

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    (Original post by geor)
    Yeeees definitely. It's usually the green chemistry questions where I lose marks. I'm hoping this paper if going to be a hard theoretical paper like the unit 1 january 2013. Then, hopefully, the grade boundaries will fall
    I'm hoping Unit 2 january 2010... 63/80 for 120/120

    ive run out of past papers and no-one is asking questions
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    (Original post by Goods)
    wanting to apply to cambridge is so soul destroying... i need(ish) 120/120 :'(
    You need an A* yeah?

    (Original post by geor)
    Same looool. We need about 78/80 for a safe 120. Tricky stuff
    What grade you hoping for? You in AS or A2?

    (Original post by posthumus)


    Wow If I got that, then I would need to get only a high D in Unit 5 (and that's if I don't improve my 68 UMS from Unit 4!)....to achieve my B
    To be honest, you know your stuff well, I don't see why you can't get 105/120 or higher

    You have the B grade in the bag, judging by your knowledge

    Why not aim for an A? You can't be that far off it can you?
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    Haha u guys are so ready, i have a lot, heres a question, whats the difference between london forces and permenent dipole, can u explain the theory behind it, i mean i knw london forces is in everything but still confused, and what do we need to knw in mass spectra and the ir thingy.?

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    (Original post by geor)
    Hoping for A*! I'm in AS you?
    Oh nice, I'm on a gap year, I've finished my A-Levels but gotta improve on my grades.

    I need 105 ums in this paper and I have my A overall. Hence to meet my uni offer.

    I'm not sure about how the A* system works for Chemistry, I think you gotta average 90% in Unit 4, 5 and 6 (the assessed practical). Not 100% sure. There were a couple of people on here who got A*'s for Chemistry (who were in the same year as me) so it definitely seems possible.

    Had I not ****** up my practicals during my time at Sixth form, I would have had my A by now and wouldn't have had to worry about Chemistry.
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    (Original post by James A)
    To be honest, you know your stuff well, I don't see why you can't get 105/120 or higher

    You have the B grade in the bag, judging by your knowledge

    Why not aim for an A? You can't be that far off it can you?
    Oh I really do screw up the exams though (still need to start past papers, will do this evening!)

    This subject really isn't for me & is way too hard! I knew unit 4 inside out & all, did every paper... went beyond the spec & I still got 68 UMS, the lowest of em all So it was frustrating!

    So far my UMS has been 88,70,68 (& got between 80-90 for practicals).

    So yh if I've got the maximum marks for practical (90). Then I need to gain 104 for a B across my 2 retakes & unit 5.
    For A I would need 164 [minimum]
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    (Original post by geor)
    Yeah same looool. I've just been reading through the textbook trying to memorize as much as I possibly can!
    woow u guys are amazing , i still have a lot to do , so can u explain the intermolecular forces and all that , cuz i always confuse myself :
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    (Original post by Mimi85)
    Haha u guys are so ready, i have a lot, heres a question, whats the difference between london forces and permenent dipole, can u explain the theory behind it, i mean i knw london forces is in everything but still confused, and what do we need to knw in mass spectra and the ir thingy.?

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    London forces: London forces are due to variations in electron density in a molecules electron cloud. If there as a slight build up in one place a temporary dipole forms. This temporary dipole can form electrostatic interactions with other temporary dipoles or induce opposite dipoles in neighbouring molecules. If a molecule is larger it has a larger electron cloud hence larger temporary dipoles can form meaning london forces are stronger in long chain molecules than short chain molecules.

    Permanent dipole dipole: When there is a difference in electronegativity between the atoms in a covalent bond a dipole is formed. If a molecule is non-symmetrical these dipoles do not cancel each other out and result in a net dipole. Just as before these dipole can induce temporary dipoles of bond to other permanent dipoles.

    Mass Spectrometry.... ..... yawn

    IR: If a molecule contains polar bonds its dipole varies as it vibrates. IR radiation is an electromagnetic wave and so can interact with this varying dipole and be absorbed as energy causing the gas to heat up (global warming). We can use spectrometry to identify radiation absorbed by different vapours. Different polar bonds and functional groups absorb different wavelengths of radiation depending on how they vibrate. This leads to characteristic absorptions that can be used to identify chemicals.
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    guys from an ir spec how do you know if it is a primary, secondary, tertiary..?
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    (Original post by charlieejobson)
    guys from an ir spec how do you know if it is a primary, secondary, tertiary..?
    I don't think you can... the IR spectrum just gives you information on functional groups present (or what type of bonds).

    You'd need additional information to figure out if it's primary, secondary or tertiary
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    (Original post by posthumus)
    I don't think you can... the IR spectrum just gives you information on functional groups present (or what type of bonds).

    You'd need additional information to figure out if it's primary, secondary or tertiary
    ok that would make sense thank you
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    are people learning all the different ranges of the different functional groups in an ir spec?
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    Ok both these formulas are used in past papers:
    1. Cl· + O3 ----> ClO· + O2
    ClO· + O3 -----> Cl· + 2O2

    2. Cl· + O3 ------> ClO· + O2
    ClO· + O -------> Cl· + O2

    Are they both correct? Which one are you supposed to use if you were answering a question?

    This was posted from The Student Room's Android App on my GT-S6500
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    (Original post by charlieejobson)
    are people learning all the different ranges of the different functional groups in an ir spec?
    Don't we get a data booklet ? :confused:


    (Original post by GAB)
    Ok both these formulas are used in past papers:
    1. Cl· + O3 ----> ClO· + O2
    ClO· + O3 -----> Cl· + 2O2

    2. Cl· + O3 ------> ClO· + O2
    ClO· + O -------> Cl· + O2 should be O·

    Are they both correct? Which one are you supposed to use if you were answering a question?

    This was posted from The Student Room's Android App on my GT-S6500
    Yup both are correct
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    What is the total number of electrons in the covalent bonds in a beryllium chloride
    molecule, BeCl2?
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    [QUOTE=posthumus;42919096]Don't we get a data booklet ? :confused:




    im not sure, does anyone know?
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    You do get a data booklet, for all chemistry exams.


    (Original post by charlieejobson)


    im not sure, does anyone know?
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    (Original post by ayat94)
    What is the total number of electrons in the covalent bonds in a beryllium chloride
    molecule, BeCl2?
    The Be atom has two bonding pairs of electrons only, so it's four electrons.
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    (Original post by posthumus)
    Don't we get a data booklet ? :confused:




    Yup both are correct
    Ok I think Ill just use the one with O3 in both, makes more sense. Thank you

    Oh and you don't get the data booklet at AS. They will give you the data in the question that would be in the data book.

    This was posted from The Student Room's Android App on my GT-S6500
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    what section of the syallabus does this come under:

    what colour is the vapour which forms when conc h2so4 is added to solid potassium iodide?
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    (Original post by charlieejobson)
    what section of the syallabus does this come under:

    what colour is the vapour which forms when conc h2so4 is added to solid potassium iodide?
    Describe and carry out the following reactions:

    'Potassium halides with concentrated sulfuric acid, halogens and silver nitrate solution'
 
 
 
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