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OCR Chemistry F322~ 4th June 2013~ AS Chemistry Watch

  • View Poll Results: How did you find the exam
    Hard A= 72
    42
    15.22%
    It was okay A= 76
    99
    35.87%
    Easy A= 79
    75
    27.17%
    Very Easy A=82
    60
    21.74%

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    best of luck everyone. just have RTFQ going through your mind.

    ...It means don't forget to "read the F***ing question" because it will make sure you bank those essential marks.
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    Good luck to everyone!
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    (Original post by wndms)
    Can anybody explain incineration?

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    Burning of polymers to produce energy
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    So what kind of weird polymers do we need to learn?
    PVC, CFC, PTFE? and?

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    (Original post by wndms)
    So what kind of weird polymers do we need to learn?
    PVC, CFC, PTFE? and?

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    just remember how to recycle them,
    by
    Using as feed stock
    Burning as fuel
    cracking to get smaller hydrocarbons
    also PVC burns and produce HCl
    by the way, i never saw any question coming up from PTFE or CFC to explain them or whatever...
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    (Original post by kelvinbeyioku)
    Depends how many akyl groups you have attached to the carbon with the functional group OH


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    You don't need to know it now, u will learn it in F324, Phenols and cyclic carbohydrates...
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    (Original post by bluedate)
    Enthalpy change of combustion is sum of reactants - products

    for formations is the sum of products - reactants

    If you're asked to calculate formation using combustion data, then reverse the signs - same goes for the other way round
    Thanks for clearing this up, kept getting mixed up.
    You don't really need to use the hess law method if you do it this way right?
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    (Original post by bluedate)
    Enthalpy change of combustion is sum of reactants - products

    for formations is the sum of products - reactants

    If you're asked to calculate formation using combustion data, then reverse the signs - same goes for the other way round
    please. please. please. what do u mean reverse the signs? For all the numbers? or just for the answer ? or ?
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    (Original post by theworld)
    please. please. please. what do u mean reverse the signs? For all the numbers? or just for the answer ? or ?
    combustion is exothermic, so it gives out energy, hence - sign for the answer
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    Is rates of reaction all about the Boltzmann distribution?
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    (Original post by Jo-Ann)
    Is rates of reaction all about the Boltzmann distribution?
    nonononono
    effects of concentration, pressure and temprature too
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    (Original post by Jo-Ann)
    Is rates of reaction all about the Boltzmann distribution?
    Think about all of Module 3 being the study of rates and the energy provided in manic different contexts in order to do so.




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    if anyone out there .help ...

    4a jan 2012
    how is 432 achieved? i got 679 but where is 432 coming from.thanks
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    (Original post by bluedate)
    You don't need to know nucleophilic addition until unit 4
    Remember that electrophilic addition think alkenes
    I was absolutely livid when went through all that effort!
    LOL.
    LIVVVVVVID!



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    can someone explain question 4

    http://www.ocr.org.uk/Images/78566-q...-resources.pdf
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    I know everything except for using infrared spectroscopy! D:
    I can't really read the dips. :afraid:
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    (Original post by PreppyNinja)
    I know everything except for using infrared spectroscopy! D:
    I can't really read the dips. :afraid:
    It really is just applying logic to be fair, just see where your noticeable dips are (theirs normally only one or two) then use your datasheet to see what bonds they correspond too, then your done
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    (Original post by Sakib)
    can someone explain question 4

    http://www.ocr.org.uk/Images/78566-q...-resources.pdf
    Im guessing 4a, so here...

    You know that Broken-Formed=Enthalpy so in this case (H-H)+(Cl-Cl) -2(H-Cl)=-184
    hence 436 + 243 - 2(H-Cl) = -184
    2(H-Cl) = -184-243-436 =-863
    H-Cl= -863/2 =-431.5
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    (Original post by joe1545)
    Im guessing 4a, so here...

    You know that Broken-Formed=Enthalpy so in this case (H-H)+(Cl-Cl) -2(H-Cl)=-184
    hence 436 + 243 - 2(H-Cl) = -184
    2(H-Cl) = -184-243-436 =-863
    H-Cl= -863/2 =-431.5
    thanks
    I didn't know you have to divide by two
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    there's just one thing if some one could clear it up for me i would be soooooo grateful
    so if you're doing bond enthalpy calculations do you do reactants - products?
 
 
 
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