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colour of fe3+ ions
I thought they were red but looking on the internet i'm seeing all sorts. In my notes I'm pretty sure it said red but on my revision sheet it says yellow. This is for AQA chem unit 5..I thought they were red but if I write that and its not going to be accepted then I'll just have too relearn it as yellow, Please could someone who is 100 percent sure confirm 
I will give rep
oh also if we have al3+ ions and put excess sodium hydroxiide do we get a colourless solution as on my revision sheet it says colourless solution since soluble but next to it I've scribbled reddish ppt..so I'm slightly confused ...the whole reddish ppt is probably wrong yes? since al isn't a transition metal and so wouldnt give a colour ...a bit confused
.will give rep as usul 
I will give rep
oh also if we have al3+ ions and put excess sodium hydroxiide do we get a colourless solution as on my revision sheet it says colourless solution since soluble but next to it I've scribbled reddish ppt..so I'm slightly confused ...the whole reddish ppt is probably wrong yes? since al isn't a transition metal and so wouldnt give a colour ...a bit confused
.will give rep as usul (edited 11 years ago)
Original post by CasualSoul
I thought they were red but looking on the internet i'm seeing all sorts. In my notes I'm pretty sure it said red but on my revision sheet it says yellow. This is for AQA chem unit 5..I thought they were red but if I write that and its not going to be accepted then I'll just have too relearn it as yellow, Please could someone who is 100 percent sure confirm
I will give rep
oh also if we have al3+ ions and put excess sodium hydroxiide do we get a colourless solution as on my revision sheet it says colourless solution since soluble but next to it I've scribbled reddish ppt..so I'm slightly confused ...the whole reddish ppt is probably wrong yes? since al isn't a transition metal and so wouldnt give a colour ...a bit confused .will give rep as usul
I will give rep
oh also if we have al3+ ions and put excess sodium hydroxiide do we get a colourless solution as on my revision sheet it says colourless solution since soluble but next to it I've scribbled reddish ppt..so I'm slightly confused ...the whole reddish ppt is probably wrong yes? since al isn't a transition metal and so wouldnt give a colour ...a bit confused
.will give rep as usul From what I remember of the AQA mark schemes, they accept the colours of Fe3+ as yellow, brown or purple.
You're correct - Al would not give a coloured solution as it is not a transition metal.
Ah we had this debate yesterday in chemistry. It is technically yellow (can vouch for this as I was doing an experiment with it yesterday) but you can say violet... we asked our teacher how they got them mixed up and she just shrugged. So in short, you can say either yellow or violet
For Al you get a white ppt [Al(OH)3] which then dissolves to [Al(OH)6]3- which is a colourless solution.
For Al you get a white ppt [Al(OH)3] which then dissolves to [Al(OH)6]3- which is a colourless solution.
Original post by Muppet Science
Ah we had this debate yesterday in chemistry. It is technically yellow (can vouch for this as I was doing an experiment with it yesterday) but you can say violet... we asked our teacher how they got them mixed up and she just shrugged. So in short, you can say either yellow or violet
For Al you get a white ppt [Al(OH)3] which then dissolves to [Al(OH)6]3- which is a colourless solution.
For Al you get a white ppt [Al(OH)3] which then dissolves to [Al(OH)6]3- which is a colourless solution.
Yeah (they describe it as straw-coloured, I think), but the purple and brown colours are due to impurities in the lab, based on what I was told last year
The colour of Fe(III) depends entirely on what it is associated with....
Fe(III) can be virtually any colour:
[Fe(SCN)]2+ is blood red
[Fe(H2O)6]2+ is orange/yellow
etc
Iron(III) hydroxide is red/brown
Iron(III) nitrate is light purple
Iron(II) hexacyanoferrate(III) is dark blue (prussian blue ink was made from it)
About the only color I haven't seen for iron(III) is green
Fe(III) can be virtually any colour:
[Fe(SCN)]2+ is blood red
[Fe(H2O)6]2+ is orange/yellow
etc
Iron(III) hydroxide is red/brown
Iron(III) nitrate is light purple
Iron(II) hexacyanoferrate(III) is dark blue (prussian blue ink was made from it)
About the only color I haven't seen for iron(III) is green
Original post by thegodofgod
From what I remember of the AQA mark schemes, they accept the colours of Fe3+ as yellow, brown or purple.
You're correct - Al would not give a coloured solution as it is not a transition metal.
You're correct - Al would not give a coloured solution as it is not a transition metal.
Original post by Muppet Science
Ah we had this debate yesterday in chemistry. It is technically yellow (can vouch for this as I was doing an experiment with it yesterday) but you can say violet... we asked our teacher how they got them mixed up and she just shrugged. So in short, you can say either yellow or violet
For Al you get a white ppt [Al(OH)3] which then dissolves to [Al(OH)6]3- which is a colourless solution.
For Al you get a white ppt [Al(OH)3] which then dissolves to [Al(OH)6]3- which is a colourless solution.
Original post by thegodofgod
Yeah (they describe it as straw-coloured, I think), but the purple and brown colours are due to impurities in the lab, based on what I was told last year
Original post by charco
The colour of Fe(III) depends entirely on what it is associated with....
Fe(III) can be virtually any colour:
[Fe(SCN)]2+ is blood red
[Fe(H2O)6]2+ is orange/yellow
etc
Iron(III) hydroxide is red/brown
Iron(III) nitrate is light purple
Iron(II) hexacyanoferrate(III) is dark blue (prussian blue ink was made from it)
About the only color I haven't seen for iron(III) is green
Fe(III) can be virtually any colour:
[Fe(SCN)]2+ is blood red
[Fe(H2O)6]2+ is orange/yellow
etc
Iron(III) hydroxide is red/brown
Iron(III) nitrate is light purple
Iron(II) hexacyanoferrate(III) is dark blue (prussian blue ink was made from it)
About the only color I haven't seen for iron(III) is green
Hey thanks everyone - really helped! I've run out today but will give rep tomorrow (unless I've repped you before so it doesn't allow me)
No metal has a colour when it is uncoordinated, it is only when you include ligands that transitions in the visible region are observed. So the colour observed is equally a characteristic of the ligand and the metal.
A short intro to the colour of TM's
The colour is due to transitions between the d orbitals. In a zero field (no ligands) they are degenerate so optical transition is possible. These d orbitals are then split in energy by the ligands, the magnitude of which is a characteristic of the ligand and the metal, but I would say the ligand is dominant. I you would like to read up on this, Crystal Field Theory is the most simple theory covering this.
This splitting of the d-orbitals is very important to the chemistry of the TM's defining the shapes of coordination spheres, magnetism of complexes etc.
A short intro to the colour of TM's
The colour is due to transitions between the d orbitals. In a zero field (no ligands) they are degenerate so optical transition is possible. These d orbitals are then split in energy by the ligands, the magnitude of which is a characteristic of the ligand and the metal, but I would say the ligand is dominant. I you would like to read up on this, Crystal Field Theory is the most simple theory covering this.
This splitting of the d-orbitals is very important to the chemistry of the TM's defining the shapes of coordination spheres, magnetism of complexes etc.
But Al would form white ppt when reacting with NaOH(or just any alkali that gives OH-), forming Al(OH)3, sodium hydroxide, which is insoluble in water and normal (aq) solutions, hence that's why it forms ppt.
But then adding specifically excess NaOH, the white ppt will then redissolve and gives a colourless solution.
If you add excess NaOH to Al3+ ions from the start, it should under go the precipitation reaction instead, and then the redissolve reaction,
though for observations, I'm not sure rather it will still be forming a lot of visable ppt at the bottem, as right after the ppt form, it should theoretically react withthe excess NaOhand redisolve quite quickly.
But then adding specifically excess NaOH, the white ppt will then redissolve and gives a colourless solution.
If you add excess NaOH to Al3+ ions from the start, it should under go the precipitation reaction instead, and then the redissolve reaction,
though for observations, I'm not sure rather it will still be forming a lot of visable ppt at the bottem, as right after the ppt form, it should theoretically react withthe excess NaOhand redisolve quite quickly.
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