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Chemistry Salters F332 june 2010 watch

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    Last year everyone in my sixth form got C's and D's and then retook it in Jan to get A's. It's a funny old life eh!
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    Anyone know why bromine is more effective at destoying ozone than Chlorine?
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    Chlorine is more effective as it breaks down to form radicals in the stratosphere (large conc of ozone present)
    Bromine breaks down in the troposphere (weaker bonding) where a lower conc of ozone is present
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    (Original post by dylan2592)
    Anyone know why bromine is more effective at destoying ozone than Chlorine?
    Just coz it's more reactive, halogens get more reactive as you go down the group
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    (Original post by xelaman)
    Chlorine is more effective as it breaks down to form radicals in the stratosphere (large conc of ozone present)
    Bromine breaks down in the troposphere (weaker bonding) where a lower conc of ozone is present
    Actually, this answers better than mine!! LOOK @ THIS ONE!
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    Halogens are more reactive as you go up the group
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    (Original post by xelaman)
    Halogens are more reactive as you go up the group
    :eek: LOL you're right!!! :p: oops!! I was thinking of group 1
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    (Original post by xelaman)
    Chlorine is more effective as it breaks down to form radicals in the stratosphere (large conc of ozone present)
    Bromine breaks down in the troposphere (weaker bonding) where a lower conc of ozone is present
    This is what I thought. But check out pg 71 of storylines book just above the yellow box on the right page. It says bromine is about 100 times more effective than chlorine.
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    (Original post by dylan2592)
    This is what I thought. But check out pg 71 of storylines book just above the yellow box on the right page. It says bromine is about 100 times more effective than chlorine.

    Maybe it would be if it was just a bromine radical (as the radical is more reactive - though why i have no idea) and its just because bromine radicals arent found near ozone to be able to break it down.

    if that makes sense.


    argh chemistry why.

    did anybody do the specimen paper? the advance notice questions on that have full on frightened me ah x
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    (Original post by kirky743)
    Maybe it would be if it was just a bromine radical (as the radical is more reactive - though why i have no idea) and its just because bromine radicals arent found near ozone to be able to break it down.

    if that makes sense.


    argh chemistry why.

    did anybody do the specimen paper? the advance notice questions on that have full on frightened me ah x
    Aww ^_^ no I haven't, do you have a link?
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    Just did the Jan 2010 paper and didn't get the reagents and conditions mark. I just wondered what reagents and conditions we actually needed to know? Thanks
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    (Original post by kirky743)
    Maybe it would be if it was just a bromine radical (as the radical is more reactive - though why i have no idea) and its just because bromine radicals arent found near ozone to be able to break it down.

    if that makes sense.


    argh chemistry why.

    did anybody do the specimen paper? the advance notice questions on that have full on frightened me ah x
    I thought a chlorine radical is more reactive than a bromine radical.
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    (Original post by Saluki-Sake)
    Aww ^_^ no I haven't, do you have a link?

    http://www.ocr.org.uk/download/asses..._unit_f332.pdf <<< This is the specimen paper

    http://www.ocr.org.uk/download/asses...adv_notice.pdf <<< this is the advance notice for the specimen paper

    the last question was awful. i think this was the paper i got lowest in aha =/
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    (Original post by kirky743)
    Oxidation of primary alcohol - excess potassium dichromate solution that has been acidified with weak sulphuric acid. This is distilled to form an aldehyde.

    Oxidation of secondary alcohol - excess potassium dichromate etc as before. Heated under reflux to form a ketone.

    Alkene ---> Alcohol : reagent is water at 70ATM pressure, 300 degrees C and in the presence of a phosphoric acid catalyst.

    Hydrogenation - (alkene to alkane) -EITHER hydrogen gas at 180 degrees and 5atm pressure with a hot nickel catalyst OR room temp and pressure with a platinum catalyst

    Alcohol ---> halogenoalkane - react with the acid of the halogen (HBr, HCl...)

    Alcohol ---> Alkene : EITHER 180 degrees c with concentrated sulphuric acid OR hot vapour over Al2O3 at 300 degreees

    Alkane ----> alkene is vapour over Al2o3

    Halogenoalkane ----> amine : react with concentrated NH2 in a sealed tube

    Halogenoalkane -----> Alcohol. Reflux with excess NaOH


    hope that helps

    if anybody finds anything incorrect in that let me know =D x

    #thanks helped a lot
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    Hi I'm back! :angelblush:
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    (Original post by Sreiza)
    #thanks helped a lot
    Thanks Sreiza, thats brilliant
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    (Original post by hollywoodbudgie)
    Ooooh pretty o_o

    Um okay!
    Initation: H20---> O* + OH*
    UV

    Propogation: H2 + OH* ---> H2O + H*

    Termination: H* + O2 ---> H2O

    idk... something like that?
    Where has the hydrogen gas come from? =S

    And also we were told propogation needs two steps i think?
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    (Original post by kirky743)
    Where has the hydrogen gas come from? =S

    And also we were told propogation needs two steps i think?
    It's a hydrogen radical that comes from the breaking apart of the water.
    It's gas because the water is water vapour.
    It's propogation because there are radicals on both sides of the equation.

    God it feels good to be back :holmes:
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    (Original post by hollywoodbudgie)
    It's a hydrogen radical that comes from the breaking apart of the water.
    It's gas because the water is water vapour.
    It's propogation because there are radicals on both sides of the equation.

    God it feels good to be back :holmes:

    Noo i meant the H2. Just by two radicals bonding together?

    Yeah but we were told to have to propogation steps - like when chlorine catalyses ozone breakdown and there are two parts of it( like two propogation reactions) - or is this just because a catalyst is involved here?

    Thanks for your help =)
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    soz im confused, propogation: H2 ( radical ? ) thanks
 
 
 
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