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OCR Chemistry F322~ 4th June 2013~ AS Chemistry Watch

  • View Poll Results: How did you find the exam
    Hard A= 72
    42
    15.22%
    It was okay A= 76
    99
    35.87%
    Easy A= 79
    75
    27.17%
    Very Easy A=82
    60
    21.74%

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    (Original post by Beanjamin)
    UV-C is absorbed by the ozone, both UV-B and UV-C can cause skin cancer, and I'm not sure about the last one, does it just absorb the UV?
    The last one is that the ozone is continuously being broken down and formed by UV radiation. O3 <-----> O2 + O
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    (Original post by Beanjamin)
    Hahah that's well funny, so are you feeling prepared for the exam?
    I'm just saying the quote below is much funnier. XD
    I'm feeling okay about it.
    (Original post by Namod)
    Don't tell me you are Ben from from beckfoot school?
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    (Original post by SheriB)
    Does anybody have the january 2013 and the mark scheme? Please can I have it?
    yep do you want it? Can send it over email if you want
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    (Original post by JimmyA*)
    The last one is that the ozone is continuously being broken down and formed by UV radiation. O3 + O <-----> 2O2
    ok thanks, I thought it might be something to do with the equilibrium but I wasn't sure
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    Here JAN13
    Attached Images
  1. File Type: pdf F322Jan13.pdf (275.1 KB, 53 views)
  2. File Type: pdf F322 MS Jan 13.pdf (433.6 KB, 51 views)
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    (Original post by d.adrian)
    On same question:
    (c) Only a small proportion of the candidates in (i) realised that the 909 kJ of heat released
    comes from 4 mol of NO; so the correct answer was 5.68 × 107 kJ.
    In (ii), candidates needed to be more specific in their answers – it was not sufficient to write that
    energy would be provided.

    IDK how to do it though
    bump
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    (Original post by karenkaur)
    Would you be able to post the answers to those questions please?

    Posted from TSR Mobile
    The pi-bond is the side-ways overlap of p-orbitals, as there is also a sigma bond in between the two carbons. It makes the electrons in the sigma bond repel the electrons in the pi-bond so the pi-bond can be easily broken off, (look up pi-bulge).

    Have to think about the others, to be fair I haven't really heard of radical polymerisation.
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    (Original post by Namod)
    Don't tell me you are Ben from from beckfoot school?
    Yes I am, who are u? :O
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    What do nitrous oxides do?Do they contribute to acid rain?
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    (Original post by JimmyA*)
    They are all electrophillic additon.
    (Original post by Sam_1996)
    Yes they are all electrophillic additions
    Nucleophillic substitution reaction is hydrolosis
    Thanks you guys
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    (Original post by karenkaur)
    Would you be able to post the answers to those questions please?

    Posted from TSR Mobile
    The first one is that the pi bond has a lower bond enthalpy than the sigma bond.
    The second one is that radical polymerisation is at 200 degreesC and high pressures whereas ziegler-natta polymerisation is at 60 degreesC and so uses less fuel reducing cost and pollution.
    The third one is that carbon dioxide takes along time to react with metal oxides and speeding this up to make it worthwhile for CCS requires too much energy.
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    (Original post by Beanjamin)
    Yes I am, who are u? :O
    Nathan from beckfoot school
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    (Original post by shomshomni)
    Hi everyone! Can anyone define le chatelier's principle for me?
    When a dynamic equilibrium is subject to a change, the equilibrium shifts in order to minimize that change
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    (Original post by d.adrian)
    bump
    The enthalpy change for that question was 909, that means that 4 mols of NO releases 909kj of energy, therefore 1 mol of NO releases 909/4 kj = 227.25.

    As you know from the volume given or some information about n(no of moles) (You haven't given me information about how many is made so I'm just assuming from calculations.)

    250000 moles of gas is produced. Therefore as you know 1 mol of NO releases 227.25kj, 250000 moles must produce, 227.25 x 250000 = 5.68x10^7kj.
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    (Original post by Sam_1996)
    What do nitrous oxides do?Do they contribute to acid rain?
    yeah, but most significantly they can produce low-level ozone. Ozone is very dangerous on the ground.
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    On past paper questions ive been doing where it asks for a 'suitable oxidising mixture for a reaction' (for example butan-1-ol to butanal) the answer is always H+ Cr2O7^2- .....why isnt it just potassium dichromate? Thats what i thought it was :/ anyone feel like explaining?? :/
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    (Original post by simifeltham)
    Suggest two factors that affect the contribution of a greenhouse gas to global warming (2)
    Atmospheric concentrations and its ability to absorb infrared radiation
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    (Original post by sladyy96)
    On past paper questions ive been doing where it asks for a 'suitable oxidising mixture for a reaction' (for example butan-1-ol to butanal) the answer is always H+ Cr2O7^2- .....why isnt it just potassium dichromate? Thats what i thought it was :/ anyone feel like explaining?? :/
    it needs acidic conditions so if you like you can write
    K2Cr2O7/H2SO4 or just K2Cr2O7/H+
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    Is it the more hydrogen bonds in the alcohol, the less volatile the alcohol?


    Posted from TSR Mobile
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    (Original post by sladyy96)
    On past paper questions ive been doing where it asks for a 'suitable oxidising mixture for a reaction' (for example butan-1-ol to butanal) the answer is always H+ Cr2O7^2- .....why isnt it just potassium dichromate? Thats what i thought it was :/ anyone feel like explaining?? :/
    Because its acidified potassium dichromate. So you either have to say acidified, say H+ or say H2S04 along with potassium dichromate.
 
 
 
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