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    I hate AQA. Why have they been so evil this year for chemistry? Piss*s me off.
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    (Original post by Boundless_x)
    Guys if something is insoluble e.g. Mg(OH)2 does it mean that ph will not be affected?
    It means pH wouldn't be as high as something that is soluble. Hence Mg(OH)2 has a pH of 10 and NaOH has a pH of 14
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    (Original post by Boundless_x)
    Guys if something is insoluble e.g. Mg(OH)2 does it mean that ph will not be affected?
    Sparingly soluble bro. pH= 9 for Mg(OH)2
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    GUYS ANY TIPS ON HOW TO DO BORN-HABER CYCLES??
    I always seem to get them wrong! Any tips?
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    [QUOTE=Hopefulmedic15;65999407]
    (Original post by Humza Ali)

    This isn't correct.

    It all depends on whether delta H and delta S are positive or negative.

    If #H is negative and #S is positive then #G is always negative

    If #H is positive and #S is negative then #G is always positive

    If #H is negative and #S is negative then the reaction is only feasible (#G is less than or equal to 0) at low temperatures

    If #H is positive and #S is positive then the reaction is only feasible (#G is less than or equal to 0) at high temperatures

    Also as temperature increases molecules gain kinetic energy so they move/vibrate more and so have an increase of disorder hence an increase in entropy
    U absolute life saver ! Tyvm


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    [QUOTE=Sexybadman;65999589]
    (Original post by Hopefulmedic15)

    U absolute life saver ! Tyvm


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    No worries you can work it out by looking at the free-energy equation so don't panic if you don't memorise which is which!
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    (Original post by GO97)
    aqa eats hopes and prayers for breakfast.
    Oh... I guess I have no chance then. :bawling:

    Good luck to you though!
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    That made me laugh tbh
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    guys do we need to know the equation for oxidation of [co(nh3)6}2+ in air if so please could you write the equation thanks.
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    Just did the Jan 2011 paper - it was a dream!! Praying tomorrow's paper is similar
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    (Original post by Suits101)
    It means pH wouldn't be as high as something that is soluble. Hence Mg(OH)2 has a pH of 10 and NaOH has a pH of 14
    (Original post by kieton123)
    Sparingly soluble bro. pH= 9 for Mg(OH)2
    Thanks
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    (Original post by lahigueraxxx)
    Just did the Jan 2011 paper - it was a dream!! Praying tomorrow's paper is similar
    Apparently AQA eats prayers for breakfast...
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    they better give us a nice paper to compensate for that disgusting chem4 paper
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    (Original post by Boundless_x)
    Apparently AQA eats prayers for breakfast...
    never. forget. chem 4
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    never
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    (Original post by Boundless_x)
    Apparently AQA eats prayers for breakfast...
    Yeah learnt that with chem4 :// One can only dream
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    (Original post by abzz11)
    guys do we need to know the equation for oxidation of [co(nh3)6}2+ in air if so please could you write the equation thanks.
    2[Co(NH3)6]2+ + H2O2 ===> 2[Co(NH3)6]3+ + 2OH-
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    (Original post by Hopefulmedic15)
    2[Co(NH3)6]2+ + H2O2 ===> 2[Co(NH3)6]3+ + 2OH-
    thanks but this isnt reacting with oxygen?
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    (Original post by GO97)
    never. forget. chem 4
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    never
    Nah... chem4 was pretty good Imo.
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    JK
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    Don't mention that foul monstrosity....
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    THE HORROR... :ahhhhh::cry2:
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    (Original post by abzz11)
    thanks but this isnt reacting with oxygen?
    reacts with air or h2o2 (hydrogen peroxide)
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    (Original post by abzz11)
    thanks but this isnt reacting with oxygen?
    It's still being oxidised from Co2+ ---> Co3+

    If it's just in air it's:

    [Co(NH3)6]2+ ===> [Co(NH3)6]3+ + e-
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    (Original post by Boundless_x)
    Nah... chem4 was pretty good Imo.
    there were actually ppl at my college saying this...my guess is that they didn't click with half of the hsw questions, either that or there all geniuses
 
 
 
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