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    Where is everyone learning their transition metal colours from? Does anyone have that Heinemann AQA Chem A2 revision book? Would anyone be able to scan in that page with the trans.colours on for addition w/Na2CO3, NH3 and HCl, that's all of the reactants...I think? I would really appreciate it! I have a colour chart from my teacher and one in the book but they are both different to the mark scheme! argh if anyone has a colour scheme that is compatible with the AQA mark schemes i would be really grateful, cos I don't know which are the right colours! p.s. is CuCO3 blue or green?? Thanks! :rolleyes:
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    Cu2+ = pale blue gelatinous ppte with NaOH
    Fe2+ = green " " "
    Fe3+ = rusty orange " " "
    [Cu(NH3)4(H2O)2]2+ = royal blue
    [CuCl4]2- = yellow
    [Cu(H2O)6]2+ = pale blue
    [Fe(SCN)(H2O)5]2+ = blood red
    [Fe(H2O)6]3+ = yellowy brown

    i'm doing OCR and these are all we need to know, but dont know about AQA sorry. have you checked the syllabus?
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    I have CuCl(4)(2-) as green, [Fe(H20)6]3+ as yellow/orange
    Hm well AQA syllabus just says colours of complexes in this module..but I think it's

    colour of
    all the vanadium ox.states,
    chromate,dichromate
    iron(II), iron (III), cobalt, aluminium, copper, chromium aqeous reactions w/Na(2)CO(3), HCl, NH3, NaOH & colours in excess
    silver reactions w/thio, NaOH and NH3

    anyone got anymore we need?
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    Ok can someone just confirm this:

    CuCO(3) = blue or green?
    [Cr(H2O)6]3+ + conc. HCl ---> [CrCl(6)]3- or [CrO(4)]2- (then [Cr(2)O(7)]2-) ?

    Thanks
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    (Original post by Asphyxiating)
    Ok can someone just confirm this:

    CuCO(3) = blue or green?
    [Cr(H2O)6]3+ + conc. HCl ---> [CrCl(6)]3- or [CrO(4)]2- (then [Cr(2)O(7)]2-) ?

    Thanks
    CuCO3 is a 'blue-green' ppt not 'blue or green'

    not sure about the second..never come accross it. shud i be worried? lol.
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    Definitely not [CrO(4)]2-

    You will need to put [Cr(H2O)6]3+ with H2O2 and OH- to do that.

    I think [CrCl(6)]3- is also green...?
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    (Original post by selkie222)
    Definitely not [CrO(4)]2-

    You will need to put [Cr(H2O)6]3+ with H2O2 and OH- to do that.

    I think [CrCl(6)]3- is also green...?
    Ok so it makes [CrCl(6)]3-?
    Is [Fe(H20)(6)]3+ yellow or brown?

    Thanks v much

    p.s. yes [CrCl(6)]3- is green
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    (Original post by ShOcKzZ)
    CuCO3 is a 'blue-green' ppt not 'blue or green'

    not sure about the second..never come accross it. shud i be worried? lol.
    hm argh so i have blue and green and blue-green, I take it it's close then so they might accept any of those answers? Did it say blue-green in the mark scheme of a past paper somewhere?
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    (Original post by Asphyxiating)
    Ok so it makes [CrCl(6)]3-?
    Is [Fe(H20)(6)]3+ yellow or brown?

    Thanks v much

    p.s. yes [CrCl(6)]3- is green
    where are you getting these complexes from..ive just got:

    [Fe(H2O)6]2+
    [Co(H2O)6]2+
    [Cu(H2O)6]2+

    [Fe(H2O)6]3+
    [Al(H2O)6]3+
    [Cr(H2O)6]3+

    with ..OH- (little), OH- (excess) NH3 (little) NH3 (excess) and Carbonate..

    where do all the Cl's come into it??:confused:
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    Actually not sure if it makes anything... [CrCl(6)]3- sounds like a reasonable choice between the two but you'll need quite concentrated HCl since Cl- is a weaker ligand than H2O.

    In my notes there is a partially cholosubstituted species [CrCl(2)H2O(4)]+ which sounds more possible.

    In the module book (I think... just checked, yes) it says that [Fe(H2O)(6)]3+ is a (scary!) pale violet(!!!) but appears yellow due to hydrolysis.

    It is brown when precipitated as [Fe(H2O)(3)(OH)(3)]

    Mark schemes are usually somewhat flexible on these points, I understand.

    I might have seen a pale violet iron(III) crystal once, but I have never seen it pale violet in solution.

    selkie
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    (Original post by ShOcKzZ)
    where are you getting these complexes from..ive just got:

    [Fe(H2O)6]2+
    [Co(H2O)6]2+
    [Cu(H2O)6]2+

    [Fe(H2O)6]3+
    [Al(H2O)6]3+
    [Cr(H2O)6]3+

    with ..OH- (little), OH- (excess) NH3 (little) NH3 (excess) and Carbonate..

    where do all the Cl's come into it??:confused:
    Vanadium?

    Yes all those above are pretty much what you need. But for several random ones--- Co, Cu they do expect you to know the colour of the tetrachloro ion.

    [CoCl4]2- is blue
    [CuCl4]2- is yellow-green (interesting little equilibrium, because if you add more water, it goes back to blue due to H2O being a stronger ligand)

    Apart from those, you might have some di-substituted chloro ions ith Cr(III) and V(III), for which a good guess is green.

    And by the way anhydrous CoCl2 is blue--- it is part of a test for water (blue to pink)

    That's all I think...

    selkie
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    (Original post by selkie222)
    Vanadium?

    Yes all those above are pretty much what you need. But for several random ones--- Co, Cu they do expect you to know the colour of the tetrachloro ion.

    [CoCl4]2- is blue
    [CuCl4]2- is yellow-green (interesting little equilibrium, because if you add more water, it goes back to blue due to H2O being a stronger ligand)

    Apart from those, you might have some di-substituted chloro ions ith Cr(III) and V(III), for which a good guess is green.

    And by the way anhydrous CoCl2 is blue--- it is part of a test for water (blue to pink)

    That's all I think...

    selkie
    Thanks, yeap I'm getting there now, slowly! Thanks so much, you've been a real help
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    Ok one more..

    When you add excess NaOH to [Cr(H2O)6]3+ do you get [Cr(OH)6]3- which is dark green soln or do you get [Cr(OH)4(H2O)2]- which is a green soln?

    Also do we need to know that Co(H2O)4(OH)2 stands in air to become oxidised to beige ppt Co(OH)3 ?

    Ok think i'm alright now thanks
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    Where are all these 6 Cl- ligand complexes from?!?!

    I was under the impression Cl- could only form 4 ligands due to size/charge etc.???
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    (Original post by kingpong)
    Where are all these 6 Cl- ligand complexes from?!?!

    I was under the impression Cl- could only form 2 ligands due to size/charge etc.???
    Good point. Yes 6 Cl- ligand complexes probably won't happen (not to the metals we are studying anyways), but 4 Cl- complexes do happen to Cu and Co (which is yellow green and blue respectively).

    (Original post by Asphyxiating)
    When you add excess NaOH to [Cr(H2O)6]3+ do you get [Cr(OH)6]3- which is dark green soln or do you get [Cr(OH)4(H2O)2]- which is a green soln?
    It seems to be possible for [Cr(OH)6]3- to get to 6OH-, partly maybe because OH- is a strong ligand... but there are reasons to do with chromium too, which we don't need to know.

    I think the most important thing to know with [Cr(H2O)6]3+ is that it forms green ppt on adding a little base, and it dissolves on excess OH- to form a green solution.

    And again [Cr(H2O)6]3+ is a (startling) "red-violet" or "ruby red" according to the module books--- however it appears green due to hydrolysis (which is what I usually see!)

    selkie
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    (Original post by selkie222)
    It seems to be possible for [Cr(OH)6]3- to get to 6OH-, partly maybe because OH- is a strong ligand... but there are reasons to do with chromium too, which we don't need to know.

    I think the most important thing to know with [Cr(H2O)6]3+ is that it forms green ppt on adding a little base, and it dissolves on excess OH- to form a green solution.
    selkie
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    I HAVENT EVEN LEARNT THOSE COLOURS YET!!, i am so going to fail 2moro
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    Here are all the transition colours I know

    [V(H2O)6]2+ = purple
    [V(H20)6]3+ = green
    [VO]2+ = blue
    [VO2]+ = yellow

    [Cr(H20)6]3+ = green
    [Cr2O7]2- = orange
    [CrO4]2- = yellow

    [Mn(H2O)6]2+ = pale pink
    [MnO4]- = purple

    [Fe(H2O)6]2+ = green
    [Fe(H2O)6]3+ = orange/brown

    [Cu(H2O)6]+ = colourless
    [Cu(H2O)6]2+ = blue
    [Cu(NH3)4]2+ = deep blue

    Hope that helps.
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    Since when do we have to know the colours?
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    (Original post by DaveR)

    [Cr2O7]2- = orange
    [CrO4]2- = yellow
    they are both Cr (VI)..shouldn't it just be orange?
 
 
 
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