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    (Original post by Davelittle)
    The mark scheme has a double bond still in?

    Take a look- June 2011 f332 Q 5. d) ii. I think!

    Really confused :/
    it's a diene, it has two double bonds originally so it, I think in diene's only one of the double bonds open up.

    In the advanced notice:
    Polybutadiene is made from the monomer
    buta-1,3-diene. The polymerisation reaction occurs
    by the two double bonds opening up, providing
    linking points to other monomer units and creating
    a new double bond between the central pair of
    carbon atoms
    Oh and by the way I used cntrl+F to find this and tbh you were looking out 1 sentance.
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    (Original post by Davelittle)
    I didn't see anything that told you how to do it, I don't even get what has happened- it looks like one of the double bonds has broken and the other moved to the middle somehow :O
    Strange, lets just hope we don't get something like that in the exam! If we do, just open up a double bond and move the other to the middle


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    (Original post by Davelittle)
    Greenhouse gases, ozone formation and destruction, polymers which ones soluble etc.
    Ah okay thanks!
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    which is stronger, c-cl bonds or c-br and why
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    (Original post by YA BISH)
    which is stronger, c-cl bonds or c-br and why
    C-Cl because chlorine is more electronegative than bromine.


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    (Original post by steviep14)
    Instead of a dot and a cross
    The covalent bond would be 2 dots or 2 crosses showing one atom provides both of the electrons
    Thanks! I worked it out 10 minutes after I posted that, I was just over complicating it.
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    (Original post by super121)
    C-Cl because chlorine is more electronegative than bromine.


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    What about bond polarity?

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    (Original post by YA BISH)
    which is stronger, c-cl bonds or c-br and why
    Edit:

    It depends, bond enthalpies:
    C-Cl is stronger due to a higher polarity caused by a higher elctronegativity which means the bonding electrons are attracted more strongly to the smaller halogens in C-Halogen bonds.
    However when talking about boiling points the larger halogens are easier to boil since their intermolecular bonds are weaker due to less polarity in their bonds.
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    (Original post by super121)
    C-Cl because chlorine is more electronegative than bromine.


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    would this be because the chlorine is smaller? and thanks for the help
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    Can someone give me sites or videos I could watch to help understand nucleophilic substitution and electrophilic addition?
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    (Original post by YA BISH)
    which is stronger, c-cl bonds or c-br and why
    (Original post by super121)
    C-Cl because chlorine is more electronegative than bromine.


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    Its more to do with the fact that the C-Cl bond has higher bond enthalpy, and therefore requires more energy to break.
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    Good Luck everyone Relax remember to watch out for sig figs!
    Even if you don't know how to solve a calculation just times and divide a little and get the sig figs for a method mark

    Edit: C-Cl is stronger as the atom is smaller, this means electrons are closer to the nucleus, this is why the bond enthalpy for C-Br is lower
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    (Original post by YA BISH)
    which is stronger, c-cl bonds or c-br and why
    C-CL bonds coz C-Halogen bond becomes weaker as the size of the halogen atom increases.
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    what would be an ideal 3/4 mark answer for solubility of polymers? i dont really know how to go into detail on it..:confused:
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    (Original post by TheNote)
    Edit:

    It depends, bond enthalpies:
    C-Cl is stronger due to a higher polarity caused by a higher elctronegativity which means the bonding electrons are attracted more strongly to the smaller halogens in C-Halogen bonds.
    However when talking about boiling points the larger halogens are easier to boil since their intermolecular bonds are weaker due to less polarity in their bonds.
    i understand the first bit but a little confused on the boiling point bit. theres a question on it in the jan 13 paper (question 2d) which has confused me.
    thank you for the help btw
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    (Original post by issy5038)
    what would be an ideal 3/4 mark answer for solubility of polymers? i dont really know how to go into detail on it..:confused:
    Hydrogen bonding causes solubility. It occurs because oxygen is small and electronegative making it partially negatively charged whereas hydrogen has a partial positive charge; this causes an attraction. -OH groups on the polymer can hydrogen bond to water molecules as the also have OH groups.
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    (Original post by issy5038)
    what would be an ideal 3/4 mark answer for solubility of polymers? i dont really know how to go into detail on it..:confused:
    I can't find many ways to ask you in detail about it, since it's mostly, does it have OH in it? Yes? Does it have lots or little OH in it:
    lots: soluble
    Little: not soluble

    Also ester groups make a polymer soluble, due to the oxygen being able to hydrogen bond.
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    (Original post by TheNote)
    I can't find many ways to ask you in detail about it, since it's mostly, does it have OH in it? Yes? Does it have lots or little OH in it:
    lots: soluble
    Little: not soluble

    Also ester groups make a polymer soluble, due to the oxygen being able to hydrogen bond.
    Having lots of hydrogen bonds means the hydrogen bonds are too strong between the molecules and therefore cannot break and join with water molecules; it requires a balance for a polymer to be soluble.
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    (Original post by YA BISH)
    i understand the first bit but a little confused on the boiling point bit. theres a question on it in the jan 13 paper (question 2d) which has confused me.
    thank you for the help btw
    I don't know, either way, the larger the atom and the more of them their are, the larger the boiling point.
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    (Original post by Hac)
    Having lots of hydrogen bonds means the hydrogen bonds are too strong between the molecules and therefore cannot break and join with water molecules; it requires a balance for a polymer to be soluble.
    Wouldn't it just slow down the rate at which it dissolves rather than reducing it's solubility? because can't water break covalent bonds in polar molecules?
 
 
 
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