sainandrew92 - 2-11-2012 at 17:27
Hey all,
Just had a lab session and supposedly I used Ammonium iron(II) sulphate for part of it.
My problem is, the salt was white and upon dissolving it in water the solution remained colourless.
I am pretty sure Ammonium iron(II) sulphate should be green and any solution produced should also be green.
Did I just use Ammonium Iron(III) sulphate instead?
nezza - 3-11-2012 at 01:04
Pure ammonium iron(II) sulphate is a very pale green and in solution it is almost colourless. You can test for the presence of iron(II) with any of
the standard Iron(II) tests, Potassium hexacyanoferrate(III) should give a blue precipitate. Potassium hexacyanoferrate(II) should give a white
precipitate although this is almost always pale blue due to oxidation of the Fe(II) and Thiocyanate should give only a pale red colour. A neat
reaction od ferrous iron is with silver nitrate. A crystalline precipitate of silver will slowly form in an equilibrium reaction and no precipitate
will form with ferric salts.
[Edited on 3-11-2012 by nezza]
Poppy - 4-11-2012 at 18:33
If you have at least 50mL solution but its low concentration, and if you dont have a precision scale, you can try the poor man's FeII meter I've
idealized on this topic (link below).
http://www.sciencemadness.org/talk/viewthread.php?tid=5650#p...
Good luck.
sainandrew92 - 6-11-2012 at 13:40
Thanks for the help guys.
Annoyingly my inorganic lab sessions ended last week, and we had potassium hexacyanoferrate(II) lying around so I could have tried your
method nezza.
Never mind, I'll just trust the technician's word.
[Edited on 6-11-2012 by sainandrew92]