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    (Original post by scorpio22)
    i meant 2013 january ...

    1ii
    welcome back to reality
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    (Original post by MedMed12)
    what do you mean went down? had you sat the paper before this Jan?
    hopefully we'll be OK. Guessing you need an A for chemchem?
    Yes I'm on a gap year, resitting. I managed the A in biology 4 & 5 but went down from B grades in chem 4 & 5 - so I'm taking them AGAAAAIN for an A.
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    (Original post by bmpink)
    The position of equilibrium changes because the concentrations of the reactants change, because if there's more on one side and less on the other... ! Sorry yes it does, force of habit! My teacher ALWAYS wrote it like that haha.
    Ah right - thanks!
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    (Original post by kevloui)
    Ok let me warm you guys up..

    Construct the equation for the oxidation of acidified iron(II) ions by oxygen


    4Fe2+ + 4H+ + O2 ----> 4Fe3+ + 2h2o
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    (Original post by otrivine)
    4Fe2+ + 4H+ + O2 ----> 4Fe3+ + 2h2o
    Yep;
    What do you understand by the term bidentate ligand?
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    (Original post by Myocardium)
    Do we need to know the half equations for hydrogen oxygen fuel alkaline cells?
    They gave it in the table didn't they? The important thing is to pick according to the conditions - I overlooked it though it was written clearly in bold.
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    (Original post by _HabibaH_)
    Yes I'm on a gap year, resitting. I managed the A in biology 4 & 5 but went down from B grades in chem 4 & 5 - so I'm taking them AGAAAAIN for an A.
    What grade did you get for chem 4 and 5 first time round if you don't mind me asking? Was it a really difficult paper?
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    (Original post by kevloui)
    Yep;
    What do you understand by the term bidentate ligand?
    wait wait wait what was answer to the other question the one about describe a test.....
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    (Original post by bmpink)
    4 moles of iron!? Where?! But do you just balance the four with 4Fe2+ and 4Fe3+?
    Yes it's because you first write the 2 half equations:
    Fe2+ ----> Fe3+ + e-
    O2+ 4H+ + 4e- ----> 2H2O and then do the full equation
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    In platin, what is the coordination number
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    (Original post by kevloui)
    Yep;
    What do you understand by the term bidentate ligand?
    A molecule or ion that can donate 2 lone pair of electrons to a transition metal ion forming 2 coordinate bonds
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    (Original post by kevloui)
    Yep;
    What do you understand by the term bidentate ligand?
    A bidentate ligand, is an ion/molecule that can donate two pair of electrons to a central metal ion forming TWO coordinate bonds.

    How is a buffer solution created and explain how it minimises changes to pH.
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    (Original post by AFC_123456789)
    In platin, what is the coordination number
    4 coordinate bonds
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    (Original post by kuku2013)
    wait wait wait what was answer to the other question the one about describe a test.....
    lol I wouldn't worry too much about it, but there's no reason why it wouldn't be a 1 marker:
    Add (aqueous) sodium hydroxide which will give a brown/rusty ppt
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    (Original post by _HabibaH_)
    They gave it in the table didn't they? The important thing is to pick according to the conditions - I overlooked it though it was written clearly in bold.
    Haha they always throw in a dodgy equation in those tables to throw us off, like those ones where two similar half eqs have the same species, and only when you are halfway through merging two equations together you realize that you overlooked the other one -_-
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    (Original post by rival_)
    In the mark scheme where does the "40" come from when working out conc^ in g dm^-3
    this
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    (Original post by kevloui)
    niiiiiiceee; although its 4 moles of the iron, but nonetheless..
    Describe a test to show the presence of iron(III) ions in a solution of FeSO4.7H2O.
    Do you add NaOH to it to get a brown ppt?
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    (Original post by otrivine)
    A molecule or ion that can donate 2 lone pair of electrons to a transition metal ion forming 2 coordinate bonds

    (Original post by liam627)
    A bidentate ligand, is an ion/molecule that can donate two pair of electrons to a central metal ion forming TWO coordinate bonds.

    How is a buffer solution created and explain how it minimises changes to pH.
    Yup, Explain why the H—O—H bond angle in the water ligand is 107° rather than 104.5°.
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    (Original post by bmpink)
    Haha i've found it! For the Zn half cell, you need 2 electrons to balance the charge, and bottom you need 2Cr2+ to balance the 2 cr on the left, 7h2o on right to balance the O7 in the dichromate and 14H+ on the left to balance the 7x2 H's on the right!
    Thank you; do you have any general tips on how to approach these?

    I find them weird aha
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    (Original post by Dr00n)
    Do you add NaOH to it to get a brown ppt?
    spot on lol
 
 
 
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