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OCR Salters Chemistry B F332 Advance Notice Jan 2011 Understanding Our Changing Atmos Watch

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    they're bringing articles into Chemistry! :lolwut:
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    (Original post by gozatron)
    I kinda do, is there anything particular you don't understand? maybe i can help.
    I know it wasn't me you were offering help to but i don't quite get it either.

    Where does the HO2• come from on the diagram? from reading the previous page i thought that the HO2• is formed alongside an aldehyde when the peroxy radicals react with NO• but on the diagram there isn't this reaction.

    I'm probably missing something obvious or have read something wrong but some clarification would be much appreciated.

    Others please feel free to help . Thanks! x
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    (Original post by MD 4p6)
    Hey guys
    The graph is a major concern for me :/ and because it's so confusing we're clearly going to be grilled about this :/ Does anyone actually understand what's happening here?
    why is it at 11.00, NO2 concentrations are the highest?
    I understand that nitrogen monoxide radicals combine with an oxygen atome to give nitrogen diooxide, so when NO concentrations are high, NO2 concentrations are low since they are inversely related.
    So my question is, from 11.00-13.30 NO2 concentrations generally decrease, so why doesn't NO concentration increase simultaneously? Instead it just flattens out......
    Has anyone got the slighest clue whats going on???
    The graphs is just show monitored levels of NO2 with ppb values. Propabaly highest at 11:00 as it was rush hour on that day or something when concentrations were being monitored. What I think they want you to be thinking is the sources of NO2 and NO which would explain the graphs well.
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    (Original post by gozatron)
    I kinda do, is there anything particular you don't understand? maybe i can help.
    so what reactions are occuring from the bubble/ cycle diagram? I got a few like the photo dissociation ones..
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    Scheme 1 reactions

    03+hv-->0+02 (photodissociation creating oxygen radical)

    0+H20----->20H (homolytic fission? radical propogation)(hydroxyl radical formed)

    20H+CH3---->CH302+(H20?) (In the presence of oxygen)

    CH302+NO+02------>HO2+CH20 (methanal formed/aldehyde, and H02 radical)

    H02+NO------->0H+N02 ( so OH can catalyse oxidation of CH3 again)

    N02+hv------->N0+0 ( regeneration of NO radical so can be used in previous reaction again,oxygen radical can react with numerous things but possibly...)

    0+02----->03 (Ozone)
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    Woop I figured out the graphs!... I think.... took me an hour lol

    ok so first of all NO2 increases due to scheme 1 which therefore causes the NO to decrease.

    The benzene reacted with the OH radical I'm guessing is a volatile organic compound (as aromatic compounds are VOCs) this decreases the amount of benzene

    The NO2 decreases after the initial rise as it reacts with the VOC.


    What do people think?

    If anyone wants to slog their way through this (or do as I did and skim) feel free: http://www.mssanz.org.au/modsim05/papers/saunders.pdf

    It has details on the experiment in the advance notice (about benzene and ozone and so forth)
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    hey here is the F332 june 2010 ms if u guys need it
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  1. File Type: pdfGCE_Chem_B_MS_F332_June101.pdf (103.7 KB, 192 views)
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    (Original post by 04rair)
    hey here is the F332 june 2010 ms if u guys need it
    have you got the paper?
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    chemsitry is amazing
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    (Original post by Swain)
    Anyone can join, don't be shy!!
    ok
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    OMG this is the most boring advanced notice yet, it literally puts me to sleep. argh!
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    After deconstructing the Advance Notice with the rest of my chemistry class, this is what we came up with:

    - Composition of the Atmosphere
    - Radical chain reactions (Initiation, propogation, termination)
    - ppb/% conversions
    - The greenhouse effect (4-7 mark question)
    - Definitions of: ... with an example

    > Photolysis - O3 + hv = O` + O2
    > Initiation - O3 + hv = O` + O2
    > Propogation - NO` --- NO2`
    > Termination - O` + O2 = O3
    > Pollutant gases - NO/NO2

    - Activities leading to production of radicals/photochemical smogs and pollutant gases
    - Effects of ozone on humans/plants etc
    - Why CFCs don't break down in troposphere; why HCFCs do
    - CFCs:

    > Properties
    > Uses
    > Alternatives to and Adv./Disadv. of these

    - Reaction of O3 with CFCs
    - Energy = Planck's constant * frequency, and using avogadro's constant
    - Reasons for faster Rate of Reaction for gases in the troposphere

    It's rather an extensive list, but we tried to come up with everything that we could think of that was relevant to the Notice.
    Hope this is of some help...
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    Hi guys, first time on TSR.
    The list looks really good, and its provided me with a lot more to think about.
    The thing that I cant get out of my head are those 2 graphs, you know the one bout NO2 concentrations and NO concentrations.
    Whats been buggin me is that one of the graphs shows the concentration going down completely, whilst the other shows the concentration increasing till 11 am and then decreasing in the sam fashion as the other graph.
    A question they could ask is why they are both different.
    Any ideas, the only idea I have is that NO may have weaker bonds than NO2 because it gets broken down earlier on in the day when the sun has just risen so the sunlight may not be of a high enough energy.
    The fact that NO2 begins to get broken down around 11 am-12 pm, when the sun is at its highest (noon time) could back this up.
    Any other ideas?
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    I hope what I have said is right. If I havent said anything right, PLEASE CORRECT ME! thanx
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    Does anyone have a copy of the june 2010 f332 question paper? Thanks
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    Extremely last notice...still, better late then never.

    http://www.4shared.com/document/-csn...JUN_10_QP.html

    It should work. I found it whilst at school and the filtering system here prevents me from opening it. Good luck everyone for the exam tomorrow.

    p.s.
    sorry if the link doesn't work.
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    Can anyone show me how to do a PPB/PPM calculation and preferably an example using gases?
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    Guys do we need to know about vacuum filtration?

    Some of the past papers (ones from the past syllabus) have questions on it.

    HELP!
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    (Original post by gozatron)
    Can anyone show me how to do a PPB/PPM calculation and preferably an example using gases?
    Well for ppm it's simply multiply the percentage by 10,000. To get the % divide the ppm by 10,000.

    so 15ppm = 0.0015%
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    (Original post by Darthdevidem)
    Guys do we need to know about vacuum filtration?

    Some of the past papers (ones from the past syllabus) have questions on it.

    HELP!
    I thought Vacuum Filtration would be tested in next Wednesday's glorious test.
 
 
 
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