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Edexcel - Chemistry Unit 2 - 4 June 2013 watch

  • View Poll Results: Which topic(s) are you finding most difficult?
    Shapes of molecules and ions
    11.66%
    Intermediate bonding and bond polarity
    15.95%
    Intermolecular forces
    9.82%
    Redox
    17.79%
    Group 2 & 7
    40.49%
    Kinetics & Equilibria
    14.11%
    Organic Chemistry - Alcohols and Halogenoalkanes
    39.26%
    Mechanisms
    26.38%
    Green Chemistry
    28.83%

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    hi guys, Im actually findin this sooo hardd... :'(

    Especially long experiment qustions like in the june 2010 paper section B q19
    These are supposed to be simple i think but i just end up guessing what I have to do which obv aint good
    Got bio on mon chem on tue and physics on wed. Im screwed!
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    (Original post by Goods)
    I do AQA must be different boards


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    ohh okay
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    so guys what books do u use ?? how many ?
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    (Original post by Gnome :))
    It's either on the page before this one, or the one before that. It would take 2 mins to find it. I worry for you if this is the attitude you take towards your revision.

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    sure...
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    I use one book that I don't really care for (edexcel textbook for AS chem) and the rest is notes, chemguide and papers
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    hey guys I need some help.

    Please can someone explain the difference between:

    Permanent dipole-permanent dipole
    Instantaneous dipole-induced dipole
    Induced dipole-induced dipole
    instantaneous dipole -instantaneous dipole.

    Ive seen these terms thrown around a lot in different contexts and am very confused. Thanks.

    ooh also, what happens to reactivity down group 2 and 7 and why? (If that makes sense)
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    (Original post by felicity95)
    hey guys I need some help.

    Please can someone explain the difference between:

    Permanent dipole-permanent dipole
    Instantaneous dipole-induced dipole
    Induced dipole-induced dipole
    instantaneous dipole -instantaneous dipole.

    Ive seen these terms thrown around a lot in different contexts and am very confused. Thanks.

    ooh also, what happens to reactivity down group 2 and 7 and why? (If that makes sense)
    right...a little confusing but here's what I know:
    London dispersion forces create instantaneous dipoles which induce dipoles in neighboring atoms/molecules. Permanent dipoles are molecules which are polar. I suppose the way you've linked them together suggests how they're bonded together?
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    (Original post by Locked_box)
    right...a little confusing but here's what I know:
    London dispersion forces create instantaneous dipoles which induce dipoles in neighboring atoms/molecules. Permanent dipoles are molecules which are polar. I suppose the way you've linked them together suggests how they're bonded together?
    hummm I understand what youre saying about the permanent dipoles in molecules which are polar, but what are London dispersion forces. Do all molecules contain London dispersion forces?
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    Do we need to know all the stats and case studies in the green chemistry chapter? Theres tons of 'BS' in it..

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    Ok just read in the edexcel blue book that the boiling temperature of HCl is greater than that of HBr or HI due to greater dipole-dipole interactions, yet on the graph HCl has a bpt of -90 whilst HBr has a bpt of -70 and Hi of -40. Surely the bpts of HBr and HI are higher, because as you go from HCl to HI the size of the electron cloud increases and hence the van der waals forces increase. is it a mistake in the book?
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    (Original post by Jayqwe)
    Do we need to know all the stats and case studies in the green chemistry chapter? Theres tons of 'BS' in it..

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    No not specifics, the textbook often elaborates far too much. Just need some examples why biofuels might be better than fossil fuels, disadvantages of biofuels, the whole ozone thing (the O3 free radial reaction you need to know) and how CFCs along with NOs destroy ozone...the section C is usually a green chemistry related question but they will give you specific information.
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    Question: are london forces or permanent dipole-dipole interactions stronger?
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    (Original post by samsimmons)
    Question: are london forces or permanent dipole-dipole interactions stronger?
    I asked my chemistry teacher the same thing, she said you can't really compare those two because the strength of london forces are greatly variable. Large atoms/molecules --> stronger london forces. whereas dipole-dipole interactions are not that variable...basically it depends on the size of the molecules held together by London forces
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    What is the proper definition of a greenhouse gas? Is it a gas that absorbs IR radiation or a gas that traps ir radiation in the earths' atmosphere?
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    Hey guys, can anyone explain to me what is and how to work out electrical conductivity of titration mixtures? :s please


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    (Original post by Jayqwe)
    What is the proper definition of a greenhouse gas? Is it a gas that absorbs IR radiation or a gas that traps ir radiation in the earths' atmosphere?
    I would say its a gas that absorbs IR radiation, and so the IR radition is said to be 'trapped' in the Earths atmosphere (as these gases are found in the atmosphere) ...


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    (Original post by Kurraiyo)
    I asked my chemistry teacher the same thing, she said you can't really compare those two because the strength of london forces are greatly variable. Large atoms/molecules --> stronger london forces. whereas dipole-dipole interactions are not that variable...basically it depends on the size of the molecules held together by London forces
    Thank you
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    (Original post by Londrinna)
    I would say its a gas that absorbs IR radiation, and so the IR radition is said to be 'trapped' in the Earths atmosphere...


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    in one of the papers it has come up I thinkkk u have to say a gas that traps ir radiation in the atmosphere AND reflects it back onto the earth
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    (Original post by senz72)
    Just the whole halogenoalkane mechanism business?

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    So, specifically, how nucleophiles attack halogenoalkanes?

    (Original post by Khurc003)
    hi guys, Im actually findin this sooo hardd... :'(

    Especially long experiment qustions like in the june 2010 paper section B q19
    These are supposed to be simple i think but i just end up guessing what I have to do which obv aint good
    Got bio on mon chem on tue and physics on wed. Im screwed!
    What bits? Keep on swimming.

    (Original post by Mimi85)
    so guys what books do u use ?? how many ?
    The George Facer book with the Jim Clarke calculations one on the side.


    (Original post by Londrinna)
    Hey guys, can anyone explain to me what is and how to work out electrical conductivity of titration mixtures? :s please

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    I don't think you need to know the Ecell stuff, that is Unit 5 in A2. You are just expected to have a basic understanding of electrical conductivity - so, when lots of ions are floating about, the conductivity will likely increase.
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    (Original post by Priya08)
    in one of the papers it has come up I thinkkk u have to say a gas that traps ir radiation in the atmosphere AND reflects it back onto the earth
    Humm oh ok


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