Sciencemadness Discussion Board

Recovering an old bottle of FeCl2

seilgu - 15-2-2021 at 07:04

There's a 500g bottle of FeCl2 that turned brown and yellow.
I'm looking for ways to turn it back to green FeCl2 crystals/solution without significant costs.

https://chemistry.stackexchange.com/questions/75762/why-woul...

According to this it's probably hydrated rust which is not solvable in water. I could add some HCl but I don't want to waste a lot of HCl on this cheap material. (If the chlorine is already in there why should I add more?)

If I just pour it all out and add water, can I expect the HCl remaining in the bottle to dissolve the iron oxides, then upon heating to drive out the water to give back FeCl2 ?


vano - 15-2-2021 at 07:09

I do not know how much you need this compound. But I was not wasting hydrochloric acid. It is also a question of how clean the product will be. With acid you can make a chloride solution at any time. If you can take a photo to understand what the situation is.

Bedlasky - 15-2-2021 at 07:19

Small amount of HCl and iron nails do the trick. Iron will reduce any Fe(III) to Fe(II).

[Edited on 15-2-2021 by Bedlasky]

ChemTalk - 15-2-2021 at 07:58

Quote: Originally posted by Bedlasky  
Small amount of HCl and iron nails do the trick. Iron will reduce any Fe(III) to Fe(II).

[Edited on 15-2-2021 by Bedlasky]


Came here to say the same thing. Steel wool will work too.

I purchased some FeSO4 once, and it turned light brown before it even arrived at my door.

unionised - 15-2-2021 at 11:00

I can't see why a simple recrystallisation wouldn't work.
The solubility curve isn't very good but it's easy to get round that.
Filtering the hot solution will strip out most of the Fe(III).
Adding a little HCl will probably help clean things up.

seilgu - 15-2-2021 at 22:03

Quote: Originally posted by Bedlasky  
Small amount of HCl and iron nails do the trick. Iron will reduce any Fe(III) to Fe(II).

[Edited on 15-2-2021 by Bedlasky]


I added a lot of HCl and a long nail but it seems to take forever. Also, do I have to use a lot of HCl for converting 500g of it?

Boffis - 16-2-2021 at 03:24

I use ferrous chloride as a reducing agent for aromatic nitro compounds but I have given up trying to prepare and store it in advance. I now prepare it as require by the method Bedlasky described. I have used up all of my old ferrous chloride and now use ferric chloride hexahydrate + HCl + soft iron nails.

ChemTalk - 19-2-2021 at 08:18

You should need very little HCl. Also the nail must be iron, and the outside of the nail should be iron, not rust / iron oxide. Personally I would try steel wool as it would have more surface area.

I find it very hard to keep Iron (II) around, I think the air in my area has a lot of oxygen in it, lol.

Quote: Originally posted by seilgu  
Quote: Originally posted by Bedlasky  
Small amount of HCl and iron nails do the trick. Iron will reduce any Fe(III) to Fe(II).

[Edited on 15-2-2021 by Bedlasky]


I added a lot of HCl and a long nail but it seems to take forever. Also, do I have to use a lot of HCl for converting 500g of it?