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    (Original post by jimmy303)
    It's like when you add zinc and HCl to Cr2O7(2-)

    Cr2O7(2-) is reduced to Cr3+ (orange to green) and is then oxidised again by zinc and HCl to Cr2+ (blue) though this is unstable and oxidises back to Cr3+ if air is present.

    In the question it says MnO4- is in excess so although some is used up to oxidise V2+ to V3+ (making Mn2+) there is still some MnO4- left over.

    Remember to check the electrode potentials. The MnO4-/Mn2+ electrode is more positive than all the reactions involving vanadium ions so MnO4- will always oxidise any vanadium ions present
    Thank you very much!!! isnt 3bii 0.6v ?
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    (Original post by strawberry_cake)
    Me too



    Aw what happened to the all nighter?? although I'm getting very tired too, I think its just the boringness of chem5 :/ I still have chaps 13-16 to review over and mod1 :cry2:

    EDIT : And that table.. I can never remember the colours
    I'll be here. :yep: :laugh:

    Table, the easy way for me anyway let's hope it works for you:

    Associate the 6 reactions with numbers 1 - 6, little OH^-, excess OH^-, little NH3, excess NH3, CO3^2-, conc. HCl

    Now take one of the 6 metal aqa ions you need to know...

    E.g. [Fe(H2O)6]^2+, write down 1 to 6 each time you get a question, first write down the formulas each one produces in each reaction you can easily learn it by just learning the ones that change, then do the colours. The Fe ones should be easy to learn.

    Group Cu and Co together cos they're special, they react with Cl- as well.

    Al goes on it's own cos really it ain't a transition metal.

    Cr, is the other odd one out cos it has loads of formulas.

    The M^2+ ones form MCO3.
    The M^3+ ones don't and effervescence.
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    10 Hours and we will be in the exam!


    Good luck everyone!
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    Ok, so I have learnt/revised pretty much everything answering exam style questions from the book. I have reached the dreaded Metal Aqua Ions and Colours ...
    Is there a way of Learning and remembering this ?? Any good techniques which you have used ? Diagrams etc.. Appreciated.
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    (Original post by Zabukar)
    Ok, so I have learnt/revised pretty much everything answering exam style questions from the book. I have reached the dreaded Metal Aqua Ions and Colours ...
    Is there a way of Learning and remembering this ?? Any good techniques which you have used ? Diagrams etc.. Appreciated.
    See above.
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    (Original post by Sparkly-Star)
    I'll be here. :yep: :laugh:

    Table, the easy way for me anyway let's hope it works for you:

    Associate the 6 reactions with numbers 1 - 6, little OH^-, excess OH^-, little NH3, excess NH3, CO3^2-, conc. HCl

    Now take one of the 6 metal aqa ions you need to know...

    E.g. [Fe(H2O)6]^2+, write down 1 to 6 each time you get a question, first write down the formulas each one produces in each reaction you can easily learn it by just learning the ones that change, then do the colours. The Fe ones should be easy to learn.

    Group Cu and Co together cos they're special, they react with Cl- as well.

    Al goes on it's own cos really it ain't a transition metal.

    Cr, is the other odd one out cos it has loads of formulas.

    The M^2+ ones form MCO3.
    The M^3+ ones don't and effervescence.
    Cheers Yeh I sort of cheated and just learnt the ones that change lol, but the colour really confuse me..I keep forgetting them, I think I'll try doing your method and see if it works..hopefully just hopefully it will.. ;D Also, for Al with xs NaOH, is it [Al(OH)4(H20)2]- or something else? The mark scheme say something different and I have this written down :/ What work are you doing now? Reckon it'll all be done by 1??
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    (Original post by Sparkly-Star)
    See above.
    Hey, you seem to know about studying the colours, I have learnt all the colours of the 6 metal aqua ions, but question, do we need to know all the Mn and V?
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    (Original post by Zabukar)
    Ok, so I have learnt/revised pretty much everything answering exam style questions from the book. I have reached the dreaded Metal Aqua Ions and Colours ...
    Is there a way of Learning and remembering this ?? Any good techniques which you have used ? Diagrams etc.. Appreciated.
    I related the colours of the complex ions to pitchers I was drinking at the pub. [Cr(Nh3)6]3+ is purple solution so purple rain! I found it worked a treat. Made chemistry much more interesting
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    Anyone? Do we need to know Mn and V colours for the individual oxidation states?
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    (Original post by joseph2008)
    Hey, you seem to know about studying the colours, I have learnt all the colours of the 6 metal aqua ions, but question, do we need to know all the Mn and V?
    No need to know them.
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    (Original post by strawberry_cake)
    Cheers Yeh I sort of cheated and just learnt the ones that change lol, but the colour really confuse me..I keep forgetting them, I think I'll try doing your method and see if it works..hopefully just hopefully it will.. ;D Also, for Al with xs NaOH, is it [Al(OH)4(H20)2]- or something else? The mark scheme say something different and I have this written down :/ What work are you doing now? Reckon it'll all be done by 1??
    I hope it's done by 1. :cry2: I'm going to make sure I don't fall asleep. :mad2: I'm gonna go over the 3 past papers. Then go over content once more because I'm very sure I've forgotten it all. It's so hard to remember these random random randommm bits of information.
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    (Original post by Sparkly-Star)
    No need to know them.
    Thank you . Good luck for tomorrow.
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    (Original post by joseph2008)
    Anyone? Do we need to know Mn and V colours for the individual oxidation states?
    No don't think so:confused:
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    (Original post by NRican)
    Why are some electron affinity endo and some exo?
    Hiyaa... The 2nd electron affinity will be endothermic because energy is requiredto overcome the repulsion. Adding an electron to an already negatively charged ion is hard
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    Do we need to know CoCl4 FeCl4 and CuCl4 Colours?
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    (Original post by strawberry_cake)
    I did the jan11 a few weeks ago, not properly, just did a q, marked it, then the next as I had soo much other stuff to do and now have forgotten about it all Btw can you help me with q 8c from the jan10 paper? I don't know which equations to use to see the ratio of the moles :/

    The titrations are annoying, I can do them but never know what to do for the last step when it wants the percentage or something...

    And I've just remembered that I still need to go through mod1 after I've been thorugh the syllabus :cry2:
    Yeah I know what you mean, dont worry about it, its very important to have confidence in urself,
    In question 8c, you use the equation of p4O10 reacted with water, this goes to h20 and 4h3po4
    and since h3po4 is a strong acid, it will neutralise naoh so you can write an equation:
    h3po4 + 3Naoh --> Na3PO4 + 3H2O

    You the can see that you have 3 moles of naoh

    i hope that helped.....
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    For Q) 3) in Jan 2010, why do in alkaline conditions, do you use the formulas where OH- is formed? Slightly confused...
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    (Original post by Sparkly-Star)
    I hope it's done by 1. :cry2: I'm going to make sure I don't fall asleep. :mad2: I'm gonna go over the 3 past papers. Then go over content once more because I'm very sure I've forgotten it all. It's so hard to remember these random random randommm bits of information.
    Same I just finished with periodicity, I always forget the acid base titrations Right, by 1 I'm gonna get through the last two chaps AND the table..or so I say lol..then read over my notes and the new papers then sleep by ummm...half 2? :/ What time will you be getting up?

    ohh and I'm yet to go through mod1 :mad:

    :mad2: haha I really like this
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    (Original post by Luke0011)
    I'm getting tired.
    any interviews?
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    (Original post by Jin3011)
    1st
    Surely either?
 
 
 
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