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    (Original post by A-New-Start)
    What ways can you make a buffer?

    adding naoh, ammonia ?
    Acid in excess + a base
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    Good Luck everybody, I hope they don't pull a Jan 2013 on us!!!!
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    (Original post by DudeBoy)
    [Cu(H2O)2(NH3)4]+2
    Thanks

    Also does anyone know the difference between tetrahedral and square planar?
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    (Original post by Myocardium)
    Thanks

    Also does anyone know the difference between tetrahedral and square planar?
    Square planar 90
    Tetrahedral 109.5
    For the most part the only square planar we need to know is Platin
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    Can someone please explain question c.ii) on June 2012?
    http://www.ocr.org.uk/Images/131289-...d-elements.pdf
    I keep getting 4.12. :/
    Answer is 4.22.
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    (Original post by alltimeemilyxo)
    oh thankyou thats a good way to remember it!
    That's ok, I have to find small tricks otherwise I get confused

    Good luck!
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    (Original post by DudeBoy)
    It's ok This helps me revise too.

    You always need to scale because by definition "The enthalphy change of neutralisation is the enthalpy change that occurs when an acid and a base react fully to form 1 mol of water"
    So always scale to 1 mole
    okay! so the only time you wouldn't need to is if you have 1 mole of acid/base?


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    do you think redox titrations will come up?
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    Anyone have a list of all the colours we need to know?
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    (Original post by georgiaaaxo)
    okay! so the only time you wouldn't need to is if you have 1 mole of acid/base?


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    Yep
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    Otrivine, what you asked about standard enthalpy change of formation being endothermic...it isn't. Bonds formed.
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    (Original post by AyshaK)
    i mean with the equal vol of water added
    Got it thanks


    Do u know why enthlpy change of formation is endothermic
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    so worried. a lot is resting on this exam for me hope it's a kind paper!


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    (Original post by DudeBoy)
    Yep
    great! thankyou so much


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    Do you ned to memorise MnO4- and I2/S2O3^2- equations or will they be given in the exam?
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    (Original post by XiLE)
    Can someone please explain question c.ii) on June 2012?
    http://www.ocr.org.uk/Images/131289-...d-elements.pdf
    I keep getting 4.12. :/
    Answer is 4.22.
    Bump
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    Quick question, what's the bond angle of square planar? And [CuCl4]2- is tetrahedral right?

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    (Original post by AyshaK)
    equal volumes of water are added but conc stays the same so the overall volume doubles and if they're asking for conc in the overall volume you'll half the conc if that makes sense?
    Which paper had this question
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    (Original post by A-New-Start)
    Anyone have a list of all the colours we need to know?
    Fe3+ + 3OH- --> Fe(OH)3 (Pale yellow to rusty brown ppt)
    Fe2+ + 2OH- --> Fe(OH)2 (Pale green to green ppt)
    Cu2+ + 2OH- --> Cu(OH)2 (Blue to blue ppt)
    Co2+ + 2OH- --> Co(OH)2 (Pink to blue ppt)

    [Cu(H2O)6]+2 + 4NH3 ---> [Cu(H2O)2(NH3)4]+2 + 4H2O (Blue solution to dark blue solution)
    [Cu(H2O)6]+2 +4Cl- ---> [CuCl4]-2 + 6H2O (Blue solution to yellow solution)
    [Co(H2O)6]+2 +4Cl- ---> [CoCl4]-2 + 6H2O (Pink solution to blue solution)
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    (Original post by otrivine)
    Got it thanks


    Do u know why enthlpy change of formation is endothermic
    It isn't. It's exothermic because bonds are made.

    I just think 'BMX'

    Bonds Made EXothermic

    Otherwise I get confused haha.
 
 
 
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