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    Now that I'm in the right thread: Anyone got the list of reaction conditions that we need to know please?
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    (Original post by davelittle)
    how would you draw the monomer of 1,3-butadiene?

    It's on june 2011 pre release
    ch2=ch-ch=ch2
    The numbers tell you where the double bonds go
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    (Original post by nksunny)
    yeah it was the iodine one which i was stuck on ... i didn't knw how to work it out cause the mark scheme said 5p6 and i ended up with 4f8 because i went up the spdf scale thing, only knw we could jump from 3p-4s-3d and no more jumping further on, obviously i was wrong -_- ... but this had made things very clear now
    Awesome Yeah we never need to say elements with f anyways so you should be fine
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    (Original post by xomaxhox)
    Now that I'm in the right thread: Anyone got the list of reaction conditions that we need to know please?
    Post 33
    http://www.thestudentroom.co.uk/show...&page=2&page=2
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    Much appreciated!
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    (Original post by Davelittle)
    It bonds by donating a pair of lone electrons in a dative covalent bond so a double bond is kind of like a nucleophile.

    Although you will be more asked about an electrophile bonding with the double bond not the other way round.
    that's my point- if the double bond is a nucleophile how can it also be nucleophilic (or did the revision guide make a mistake here ) :confused:
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    (Original post by super121)
    ch2=ch-ch=ch2
    The numbers tell you where the double bonds go
    Sorry I meant the repeating unit!
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    (Original post by xomaxhox)
    Now that I'm in the right thread: Anyone got the list of reaction conditions that we need to know please?
    here you go
    Attached Files
  1. File Type: docx chemistry.docx (14.3 KB, 108 views)
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    can someone explain half-equations to me please?
    which end of the equation do you add the electrons?
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    (Original post by tasniaa)
    can someone explain half-equations to me please?
    which end of the equation do you add the electrons?
    it depends on the equation e.g if you asked to write a half equation of the formation of chlorine molecules from chloride ions you'd get 2Cl- >Cl2 + 2e but if it was the formation of chloride ions then the half equation would be the other way around, just make sure you read the question carefully
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    (Original post by Whostolemycookie)
    Another question, when doing past papers do you analyses the advance notice it comes with?
    i asked my teacher this. He said because it's specific, it's better to see what kind of questions they usually ask with the pre-release. So that's what I do.
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    Heyy how would I go from % to pptv?


    Posted from TSR Mobile
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    (Original post by madrevision)
    it depends on the equation e.g if you asked to write a half equation of the formation of chlorine molecules from chloride ions you'd get 2Cl- >Cl2 + 2e but if it was the formation of chloride ions then the half equation would be the other way around, just make sure you read the question carefully
    oh I get it, thank you
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    (Original post by Branny101)
    Heyy how would I go from % to pptv?


    Posted from TSR Mobile
    just divide by 100 and multiply by 10 ^12 because if you had 2 pptv - it's the same as 2/1000 000 000 000 as a percentage is 2/1000 000 000 000 x 100.
    or 2pptv is 2/ 10 ^12 percentage is 2/10^12 x 100 so you just undo what you've done(i.e divide where you've multiplied) this is kinda hard to explain with large numbers.. :cool:
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    (Original post by tasniaa)
    you know in the equilibrium questions they state H = +x or -x

    how do we know which side is exo/endothermic?
    It usually tells u that, the enthalpy change of the reaction e.g. is +450kJmol-1.
    In this case, the forward reaction gives this enthalpy change, so the forward reaction will be endothermic, so an increase in temperature will move the position of equilibrium to the right, in the endothermic direction.

    Hope this makes sense
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    (Original post by Davelittle)
    Sorry I meant the repeating unit!
    Just open up the double bonds
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    Does anyone know how to represent an electron in a dot and cross diagram for an ion, if it has been electron had come from somewhere else, for instance if i said give the dot and cross diagram for a OH- ion.:confused:
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    (Original post by madrevision)
    just divide by 100 and multiply by 10 ^12 because if you had 2 pptv - it's the same as 2/1000 000 000 000 as a percentage is 2/1000 000 000 000 x 100.
    or 2pptv is 2/ 10 ^12 percentage is 2/10^12 x 100 so you just undo what you've done(i.e divide where you've multiplied) this is kinda hard to explain with large numbers.. :cool:
    I'm confused, is it basically:
    pptv to percentage /10^12 x 100
    percentage to pptv is x 10^12 /100?
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    (Original post by tipani)
    It usually tells u that, the enthalpy change of the reaction e.g. is +450kJmol-1.
    In this case, the forward reaction gives this enthalpy change, so the forward reaction will be endothermic, so an increase in temperature will move the position of equilibrium to the right, in the endothermic direction.

    Hope this makes sense
    it does, thank you!

    So say the equilibrium shifts towards the reactants, does this make more or less products?
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    (Original post by tipani)
    Does anyone know how to represent an electron in a dot and cross diagram for an ion, if it has been electron had come from somewhere else, for instance if i said give the dot and cross diagram for a OH- ion.:confused:
    leave the gained electron clear? like this o
    but colour the rest in?

    I hope that makes sense xD
 
 
 
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