Sciencemadness Discussion Board - Drying Out Iron Chloride

Drying Out Iron Chloride

mrjeffy321 - 27-6-2005 at 16:50

I have/had a solution of Iron (III) Chloride. I wanted to extract the Iron Chloride out of solution, so I decided to evaporate all the water off and just collect the crystals that form, right? Wrong, appearently, it is very hygroscopic making it some what difficult to actually dry it. I have gotten it to a thick, dark brown, "muddy" lucking substance, but it wont dry any further. I am attempting to evaportate off the water in the hot summer sun, but after about a week at this same stage, it hasnt changed.

Is there another way of de-hydrating, this substance that seems to just love water?

I cant really heat it very much (using an oven or flame) because, for one, I have it in a plastic container because Iron Chloride acts like an acid on metals, so I dont want to melt the container, and two, I think that the Iron Chloride melts and deomposes at a very low temperature, so I dont want to alter the substance either.

I suppose, in theory, if I could put it in a container that is air tight, the lower the pressure sugnificantly, I could lower the boiling point of water and pump the steam out. But this is a little to much in the way of building something than I had intended. Is there an easy chemical way?
Once I get it dried out, all I need to do is make sure I keep it in a sealed container, so as not to let any more water get to it.

Darkblade48 - 27-6-2005 at 17:09

Well, the ferric chloride melts at 37 C, if that means anything

Have you tried putting it into an airtight container that just contains some CaCl2? You just need a dessicating agent, and I'm pretty sure it'll suck the water right out

12AX7 - 27-6-2005 at 17:22

Few salts melt at 37C, that's got to be hydrate.

Desscant will do it, unless FeCl3 is a stronger dessicant!

Even so you have an equilibrium so an amount of dry CaCl2.0H2O will take some out, if not necessarily all of it.

Vacuum would do it too, I don't see why not.

Tim

Oh yeh

chloric1 - 27-6-2005 at 19:39

All the dessication already mentioned should work but you will have the hexahydrate. I suspect you want this as a catalyst so you would need the anhydrous salt. If you do get the dry hexahydrate, try heating in a stream of HCl gas.

Otherwise, I know of at least a couple of sources that sell the anhydrous material as a solid for making PCB etchant. One is a frequent seller on ebay"searhc for chloride" the other is Electronix Express or something like that. These are 1 lb lots sealed airtight in a plastic bag. Both are cheap like $10 or less.

mrjeffy321 - 27-6-2005 at 19:59

Quote:

Originally posted by chloric1
All the dessication already mentioned should work but you will have the hexahydrate. I suspect you want this as a catalyst so you would need the anhydrous salt. If you do get the dry hexahydrate, try heating in a stream of HCl gas.

How can you have dryhexahydrate, sounds like an oxymoron to me?
And this dry hexahydrate will not work as a catalyst?

I am not familiar with dessication, what does this process involve?
It sounds a little complicated, especially the part of heating it in a stream of HCl gas.

I am a fish - 27-6-2005 at 23:47

Quote:

Originally posted by mrjeffy321
I have/had a solution of Iron (III) Chloride. I wanted to extract the Iron Chloride out of solution, so I decided to evaporate all the water off and just collect the crystals that form, right? Wrong, appearently, it is very hygroscopic making it some what difficult to actually dry it. I have gotten it to a thick, dark brown, "muddy" lucking substance, but it wont dry any further.

The thick dark brown sludge may have been iron hydroxide. Iron(III) chloride solution is very prone to decomposition:

FeCl3 + 3H2O → 3HCl + Fe(OH)3

This reaction is the reason why most electronics suppliers usually sell iron(III) chloride as a solution. When dry iron(III) chloride is added to water, it is liable to give out plumes of hydrogen chloride.

Nicodem - 28-6-2005 at 12:18

FeCl3 is a very strong Lewis acid and H2O is a weak base, but still enough basic to make it impossible to dehydrate FeCl3×6H2O to FeCl3.
The hydrate decomposes to HCl, H2O and Fe (hydr)oxides when heated and I think that even the drying in the HCl stream would not prevent this (at least it would not yield an FeCl3 useful as a Lewis acid catalyst). Same goes for all other Lewis acids (like AlCl3, ZnCl2, SnCl2 and SnCl4) whose hydratated salts can't be dehydrated without decomposition/hydrolysis of the chloride.

FeCl3 can be made from the elements, but if you can simply buy it than do so as playing with Cl2 is not healthy at all.

mrjeffy321 - 28-6-2005 at 14:13

So, it seems it cant be done, or if so, it is too much work.

I did make it once though, accidentally, I have an iron alligator clip suspended over a bottle I was conducting electrolysis in over night. When I checked it the next morning, there wasnt much of an alligator clip lieft, but lots of a yello/orange stuff left behind.

Is there any reason I should save the dark stuff I have (Iron Hydroxide?), is it good for anything, or perhaps bad for putting down the drain?

Chris The Great - 28-6-2005 at 15:17

Weird, I boiled a solution of FeCl3 to dryness and appeared to get hydroxides and crap (it also ate up my copper stirstick). However, left out for a night turned them into liquid, suggesting that it is not in fact iron hydroxide as that isn't hydroscopic. But, it doesn't dissolve much in water.

Anhydrous FeCl3 melts at about 305*C and begins to decompose into FeCl2 and Cl2 at 315*C.

Perhaps boiling off the water under vacuum? Might be the easiest way to avoid decomposition, especially if you did it at room temperature.

Anhydrouse iron(III)chloride (FeCl3)

Lambda - 28-6-2005 at 17:26

mrjeffy321, don't give up so soon man !.

Making anhydrouse Fe(III)Cl3 from Fe(III)Cl3.6H2O (from solid crystaline product).

PROPERTIES:
Anhydrouse iron(III)chloride (FeCl3) melts at 306 deg.C and boils at 315 deg.C. At it's boiling point it starts to decompose into iron(II)chloride (FeCl2) and Chlorine gas (Cl2).

PROCEDURE # 1
If you keep the temperature below 315 deg.C, it should not decompose. You should have the hydrated form (Fe(III)Cl3.6H2O when it's crystaline. You want the Anhydrouse form, so this hydrated crystaline form has to lose it's crystal water. You will then have to heat it for a while from an orange-yellow solid to a brown-black solid. This brown-black solid will be your anhydrous FeCl3. If you keep your temperature between say 200 - 250 deg.C, you should eventually be able to get the anhydrouse form. This may however take a while.

Making Anhydrouse Fe(III)Cl3 from an Fe(III)Cl3-solution (from dissolved Fe(III)Cl3 in water)

PROCEDURE # 2
Another way, would be to extract your iron(III)Cl3 solution in water by shaking it with Diethyl ether, commonly known as Ether. Iron(III)Cl3 is highly soluble in Diethyl ether, and Diethyl ether and water are just about insoluble in each other. All you will have to do, is to seperate the two (the Iron(III)chloride solution with Diethyl ether should be the top layer), evaporate the Diethyl ether and you should have your dry Iron(III)Cl3.

Remark: Make shoure you don't disgard the wrong layer, keep them both, just in case.

CAUTION !: When draying Iron(III)Cl3 at high temperatures, toxic fumes are evolved. Evaporating Diethyl ether should not be done with an open flame, for these fumes form highly explosive mixtures with air. Diethyl ether is allso highly flamable.

Please allso look here for more information:

http://www.answers.com/topic/ferric-chloride

I HAVE NOT TESTED BOTH METHODES, THEY ARE BASED ON AN ASSUMPTION !

neutrino - 28-6-2005 at 17:42

>If you keep the temperature below 315 deg.C, it should not decompose.

That refers to the anhydrous form, not the hydrate.

I don't know about the second one. What you have in solution is Fe(H2O)63+. Although some would turn into Fe3+, the equilibrium would probably favor the hydrated form in this case.

Lambda - 28-6-2005 at 19:05

What I meant was:

This brown-black solid will be your anhydrous FeCl3. If you keep your temperature between say 200 - 250 deg.C, you should eventually be able to get the anhydrouse form. This may however take a while.

and if you then:

If you keep the temperature below 315 deg.C, it should not decompose.

neutrino - 28-6-2005 at 19:29

The problem is the following equilibrium:

Fe(H2O)63+ <----> Fe(OH)3 + 3H+

At room temperature, this equilibrium lies to the left. If the solution is heated, the equilibrium is shifted right and solid iron (hydr)oxides are formed as a colloidal suspension, while HCl evaporates.

Lambda - 28-6-2005 at 19:58

What about then adding extra HCL to the water solution of Fe(III)Cl3 ?.

neutrino - 29-6-2005 at 05:00

It would largely evaporate. Dehydrating in an atmosphere of HCl might work, though. I know that some other unstable chlorides can be dehydrated this way.

FrankRizzo - 29-6-2005 at 19:25

Fer Christ sake, just put it in a shallow pyrex baking disk and toss it in the oven on low heat for an hr. or two.

[Edited on 30-6-2005 by FrankRizzo]

Lambda - 29-6-2005 at 21:37

Then just use my procedure # 1 and exract the Fe(III)Cl3 with ether.

So,.....now it's off my back FrankRizzo !

mrjeffy321 - 30-6-2005 at 00:37

just evaporating off the water with a low heat does sound the easiest that is for sure.
Now i just need to find a propper container to do it in.

Ferric Chloride, Crystalline

12AX7 - 2-9-2006 at 13:33

This started as an etch/pickle/wash solution for iron. After a while of use, I concentrated it and evaporated it down. It quickly got to be deep red/brown and quite smelly due to remaining HCl, so I put it in a solar still on the warm stove and distilled the acid and water out instead.

After a while, I discovered it was evaporating quite slowly because crystals, acicular yet relatively thick (about 1 cm at the longest, by 1mm at the thickest, not sure what cross section is), were obstructing the process. I broke up the mat and piled the matter to one side, setting the jar to the other, so the syrup drained out. I washed once with muriatic acid and have been sort-of drying the crystals since. See picture.

The product i currently have is kind of gummy yet.

I wonder, think I could dehydrate this, dry at least, maybe even anhydrous, if I used concentrated sulfuric acid with a little salt (to provide initial HCl gas in the jar)?

Edit: the picture looks greener than it should. That's kind of odd. The color is really pretty drab, nothing particularly pure.

Tim

[Edited on 9-2-2006 by 12AX7]

Chem_FeCl3.jpg - 38kB