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OCR Chemistry A - Transition Metal Colours, common colour changes?

Hey everyone, I'm struggling to remember all the colour changes for the transition metals. I was wondering if there are some key common reactions or rules I can learn that will help. Thanks.
Reply 1
Avatar for juman786
juman786
4
Sorry dude as far as i know, you just gotta remmeber them...

Reactions with OH-:

- Fe(OH)2 - Green ppt (if left in the air for a while , this is oxidised to Fe(OH)3 and turns to a brown ppt

- Fe(OH)3 - Brown ppt

- Co(OH)2 - Blue ppt

- Cu(OH)2 - Light blue ppt

(YOU MUST STATE PPT!)

Reaction with Cl2:

- CuCl2 - Pale yellow

- CoCl2 - Blue

Transition metals in solution:

- [Fe(H2O)6)]2+ - Pale green

- [Fe[H2O)6]3+ - Pale yellow

- [Co(H2O)6]2+ - Pink

- [Cu(H2O)6]2+ - Light Blue

- [Cu(H2O)2(NH3)4]2+ - Dark Blue



Transition Metals in reaction with SCN forms a Blood Red Colour


When titrating a solution against MnO4-, the end point will have a pale pink colour therefore no pH indicator is required.


Try to learn these GL =)
Reply 2
Avatar for Josh-H
Josh-H
OP
14
juman786
Sorry dude as far as i know, you just gotta remmeber them...

Reactions with OH-:

- Fe(OH)2 - Green ppt (if left in the air for a while , this is oxidised to Fe(OH)3 and turns to a brown ppt

- Fe(OH)3 - Brown ppt

- Co(OH)2 - Blue ppt

- Cu(OH)2 - Light blue ppt

(YOU MUST STATE PPT!)

Reaction with Cl2:

- CuCl2 - Pale yellow

- CoCl2 - Blue

Transition metals in solution:

- [Fe(H2O)6)]2+ - Pale green

- [Fe[H2O)6]3+ - Pale yellow

- [Co(H2O)6]2+ - Pink

- [Cu(H2O)6]2+ - Light Blue

- [Cu(H2O)2(NH3)4]2+ - Dark Blue



Transition Metals in reaction with SCN forms a Blood Red Colour


When titrating a solution against MnO4-, the end point will have a pale pink colour therefore no pH indicator is required.


Try to learn these GL =)


Thank you! That's pretty much just what I was looking for, I'll have a revision session trying to learn them after :smile: Thanks again.
Reply 3
Avatar for juman786
juman786
4
Np
What does SCN stand for?
Original post by Neptism
What does SCN stand for?


Another test for iron(III) ions is to add a few drops of potassium/ammonium thiocyanate (KSCN or NH4SCN) solution and a blood–red coloured compound is formed.

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