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    OK I'm going guys (to eat breakfast)
    If I don't come back to tsr; then GOOD LUCK AND HOPEFULLY WE CAN DO REALLY WELL!!!!!!
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    (Original post by Ali_Ludley)
    I know that, you dont get marks for IDID, you have to write instantaneous dipole induced dipole bonds to get the mark, I was just stating examples though so I couldn't be bothered writing them out.
    Just a heads up to anyone else.
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    Can someone explain nucleophilic substitution and electrophilic addition to me?
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    does simple molecular structure also imply covalents bonding, or do i have to say simple molecular structure with dovalent bonding directly? same goes with giant lattice strucutre, does just giant lattice structure imply covalent bonding, or do i have to say hpgiant lattice structure with covalent bonding?

    do we say radiate or do we say re-emit for IR radiationreleased from molecules?

    thanks
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    Why are HCFC's broken down in troposphere but not in stratosphere?????
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    (Original post by krisshP)
    does simple molecular structure also imply covalents bonding, or do i have to say simple molecular structure with dovalent bonding directly? same goes with giant lattice strucutre, does just giant lattice structure imply covalent bonding, or do i have to say hpgiant lattice structure with covalent bonding?

    do we say radiate or do we say re-emit for IR radiationreleased from molecules?

    thanks
    I say re-emit
    And you don't have to say covalently bonded but add it just incase
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    What's an amine?
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    (Original post by _FDarr13)
    What's an amine?
    amonnia is N with four hydrogens

    Amine is N with 3 or less hydrogens
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    (Original post by SyedaK)
    Can someone explain nucleophilic substitution and electrophilic addition to me?
    Nucleophilic substitution is where a nucleophile (A molecule or element with a lone pair of electrons that it can donate to form a new covalent bond) substitutes with an atom or group on a (normally) halogenoalkane or alkane.
    The electrophilic addition is where a molecule approaches another molecule (Normally a bromine molecule to a alkene) with a DOUBLE BOND. Then the (example here Br2 and C2H4) bromine becomes polarised as its electrons in the bond are repelled down the bond and then the double bond in the ethene breaks and the Br-Br bond breaks hetrolytically and a C-Br bond forms. Whats left is a Carbocation and a negatively charged bromine ion which then rapidly form the last bond. Forming C2H4Br2.
    The main differences are the substitution (Leaving another product) compared with addition (leaving no extra products) and also in electrophilic involves double bonds.
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    (Original post by Davelittle)
    Why are HCFC's broken down in troposphere but not in stratosphere?????
    I believe that this is because the UV radiation in the stratosphere isn't strong enough for photodissociation to occur (isn't strong enough to break the bonds in the HCFC), while it is in the troposphere.
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    (Original post by Kathiye)
    I believe that this is because the UV radiation in the stratosphere isn't strong enough for photodissociation to occur (isn't strong enough to break the bonds in the HCFC), while it is in the troposphere.
    I thought it was because they had weaker intermolecular bonds so could break down in troposphere so didn't need much energy
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    (Original post by SyedaK)
    I thought it was because they had weaker intermolecular bonds so could break down in troposphere so didn't need much energy
    Sorry, you're right! I got confused for a moment there. They break down in the troposphere, before they reach the stratosphere. Is that right?
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    (Original post by Kathiye)
    Sorry, you're right! I got confused for a moment there. They break down in the troposphere, before they reach the stratosphere. Is that right?
    That's correct. Otherwise, they wouldn't be a useful replacement if they were to photodissociate in the stratosphere and react with ozone.
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    (Original post by Kathiye)
    Sorry, you're right! I got confused for a moment there. They break down in the troposphere, before they reach the stratosphere. Is that right?
    No... CFC's are highly unreactive and are onbly broken down by high energy radiation (UV), O3 block most UV so CFC's are only broken down in the stratosphere

    EDIT: sorry thought we were talking about CFC's xD not alternatives
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    I think you might be saving my chemistry A-level...
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    Exam in 27 minutes. Now off to school. Good luck guys!
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    So how did everyone find it? I thought it was very average, many repeated questions from past papers... I did find the naming of the molecule at the end of question 1 odd...

    Pre release questions were very nice imo, especially the 6 marker at the end. Hope everyone found it ok!
    • Thread Starter
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    What did everyone get for what type alcohol it was?
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    (Original post by cheetahs56)
    What did everyone get for what type alcohol it was?
    Tertiary
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    Systematic name of hydrogenated Z-cimene (or however you spell it)
 
 
 
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