Sciencemadness Discussion Board

how to precipitate ferrous oxalate in solution

veerendra - 31-1-2014 at 20:04

Behavious of ferrous oxalate is very complex, I got a pink colour solution during leaching iron oxides using oxalic acid. But I could not able to get it precipitate ?

I added some alchohal but it not precipitates.

any body has any idea.

mnick12 - 31-1-2014 at 20:31

I don't think you have any ferrous oxalate, it is very insoluble in water.

blargish - 31-1-2014 at 20:44

Quote: Originally posted by mnick12  
I don't think you have any ferrous oxalate, it is very insoluble in water.


When conditions are right ferrous oxalate can stay in solution, as I found out when I tried to synthesize it by mixing ferrous chloride and oxalic acid. I got a yellow solution, but upon heating the ferrous oxalate began to precipitate. I'm not exactly sure of what caused this.

However, the fact that veerendra got a pink solution suggests that it wasn't ferrous oxalate...

mnick12 - 31-1-2014 at 21:44

Ferrous oxalate is only sparingly soluble in water, the soluble compound you generated was likely some sort of transient coordination compound.

DraconicAcid - 31-1-2014 at 22:30

Pink? Might there be a manganese impurity in your iron oxide?

cyanureeves - 1-2-2014 at 11:07

maybe if you evaporate it you might attain pink crystals or powder,nice either way.

blogfast25 - 2-2-2014 at 06:55

Quote: Originally posted by DraconicAcid  
Pink? Might there be a manganese impurity in your iron oxide?


'veerendra' is also the member who is trying to separate Mn and Fe oxides using oxalic acid:

http://www.sciencemadness.org/talk/viewthread.php?tid=28564#...

But Mn<sup>2+</sup> pink colour is really only apparent at quite high concentrations or in solids like MnCl<sub>2</sub> hydrate. Also, Mn (II) oxalate is poorly soluble in water, 0.028 g / 100 g water at 20 C acc. Wikipedia.

[Edited on 2-2-2014 by blogfast25]

mnick12 - 2-2-2014 at 11:24

Again my guess is some sort of coordination complex, any sort of electron transfer in the d-orbitals produces intensely colored compound.

DraconicAcid - 2-2-2014 at 12:18

Quote: Originally posted by blogfast25  

But Mn<sup>2+</sup> pink colour is really only apparent at quite high concentrations or in solids like MnCl<sub>2</sub> hydrate. Also, Mn (II) oxalate is poorly soluble in water, 0.028 g / 100 g water at 20 C acc. Wikipedia.


But tris(oxalato)manganate(III) is cherry red- a small amount would make the solution pink.

http://pubs.acs.org/doi/abs/10.1021/ic00197a041

blogfast25 - 2-2-2014 at 12:47

I didn't know there was such a thing. But how to get Mn as Mn(III), in this context? That doesn't really happen 'accidentally', I think...

[Edited on 2-2-2014 by blogfast25]