rikkitikkitavi - 17-3-2004 at 11:27
sounds simple,
Fe(OH)3 (s) + 3 HCOOH (aq) should give
Fe(HCOO)3 (aq) + 3 H2O
but not, only a fraction reacts...
iron formate is so soluble that it should not be a problem...
so what is the reason for this?
/rickard
vulture - 17-3-2004 at 13:14
Intruiging.
Maybe the formic acid can also act as a ligand for Fe3+?
Now that I think of it, there isn't any Fe3+ in solution because we're dealing with Fe(OH)3...
One possible explanation down the toilet...
EDIT:
(HCOO)3Fe, C3H3FeO6, MR 190,90. E. bildet ein Monohydrat, rotes Kristallpulver, lösl. in Wasser, wenig lösl. in Alkohol, lichtgeschützt
aufbewahren; hydrolysiert in Wasser z. T. unter Bildung bas. Formiate. Wird gegen Eisenmangel-bedingte Blutarmut verwendet.
Lit.: Beilstein E IV 2, 18 ï Gmelin, Syst.-Nr. 59, Tl. B, 1929–1932, S. 519 f. ï Kirk-Othmer (4.) 14, 880.
It says store protected from light, partially hydrolyses in water forming basic formiates. Red crystal powder.
[Edited on 17-3-2004 by vulture]
chemoleo - 17-3-2004 at 13:23
The question is, how did you obtain the Fe(OH)3?
I am quite certain you couldnt dissolve Fe2O3 in formic acid, so maybe you got some oxo-forms that dont react well.
Try to dissolve your hydroxide in dilute H2SO4/HCl, I am sure that would work. Presumably the same for Fe2O3. Then react it with Ca-formiate, filter
off the CaSO4 and voila u may be (
) left with iron formiate.
rikkitikkitavi - 17-3-2004 at 22:43
yes, I was suspecting that it had something to do with the very low solubility of Fe(OH)3 , a formic acid solution is simply not acid enough to give
any Fe3+ concentration to speak of
[Fe3+]*[OH-]^3 = 2*exp -38 (solubility product)
and Fe3+ is unstable in aqeous solution , it easily forms basic salts aswell.
thanks for the help
/rickard