Sciencemadness Discussion Board - Preparing Ferric Chloride (III)

Preparing Ferric Chloride (III)

thorazine - 2-5-2010 at 16:20

Hi!
I'm trying to prepare some Ferric Chloride (III). I reacted some Iron powder in excess with cheap HCl, and evaporated the solution to dryness. I've got a yellow/green powder that should be FeCl2. Now i'm thinking dissolve it in water, add HCL in stoichiometric proportion and oxidize it to FeCl3. I don't have Nitric Acid, can i use some H2O2? It will work? How can i test it is really FeCl3 or FeCl2?

Thanks!

bbartlog - 2-5-2010 at 16:49

Pretty sure H2O2 would work, but you can also just bubble air through it assuming you have an aquarium pump and tubing. Since this would tend to exacerbate the HCl fumes you'd want either to either vent or scrub the exiting gases, though. Fe(Cl)3 should be red rather than green; however I don't have any good suggestion as to how to determine the exact proportion or degree to which the conversion is complete.

IrC - 2-5-2010 at 17:02

The color of iron(III) chloride crystals depends on the viewing angle: by reflected light the crystals appear dark green, but by transmitted light they appear purple-red.

aonomus - 2-5-2010 at 17:32

Just bubble air through it or let it sit open to air for a while. If you don't have any method of removing HCl fumes from your workspace, just add H2O2 and let it sit until its dark brown.

Sedit - 2-5-2010 at 17:48

Won't the Fe(II) salt mixed with H2O2 react to produce the fentons reagent AKA a pretty damn violent reaction. I have dripped 35% H2O2 onto a pile of Fe(II)sulfate and these crystals indeed turn a blood red color with a large evolution of heat.

I would suggest a dilute solution of H2O2 if thats your goal.

aonomus - 2-5-2010 at 18:07

When you react Fe(0) with HCl(aq), don't you obtain Fe(III), and its the Fe(III) that reacts with Fe(0) to form Fe(II)?

Powdered Fe(II) with 35% H2O2 is a pretty high effective concentration, I would think that with sufficient dilution dropwise 35% into solution won't be as bad, but you're still right about the peroxide being a pretty strong oxidant.

When I was making FeCl2 in bulk, I ended up reacting FeCl3 acidified with HCl with massive excesses of steel wool followed by filtration. The hard part was keeping everything in the Fe(II) state while drying the solution, but I eventually got it all to FeCl2 powder. Its fairly air sensitive, but if you work quickly it will stay in the Fe(II) form. Having said that, leaving it out for a few hours will easily turn it all to Fe(III).

12AX7 - 2-5-2010 at 18:54

Iron dissolved in acid produces no Fe(III), the reduction potential is greater than H+. Indeed, Fe(III) is more "noble" than Cu(II).

A few hours won't make much Fe(III), but a month or so will turn your bluish-green solution a nice sickly brown.

Incidentially, pure FeCl3 in acid (a deep red solution) releases a small amount of chlorine. The equilibrium in air is more like Fe(3-x)+ with x small (maybe 0.1-0.2?). It probably depends on pH (low pH generally destabilizes high oxidation states), acid type and concentration, temperature and so on.

Tim

JohnWW - 2-5-2010 at 19:27

Although the Fe+++ cation is very susceptible to hydrolysis in aqueous solution, and indeed exists as the yellow FeCl4- anion in solution in an excess of aqueous HCl, it can be crystallized from such a strongly acid HCl solution as yellow-brown deliquescent crystals of the composition FeCl3.6H2O, melting-point 37ºC, in which the Fe(III) is present as [Fe(H2O)6]+++.

But if you want anhydrous FeCl3, which would be needed as a catalyst (as an alternative to AlCl3) for reactions such as Friedel-Crafts alkylations and acylations, the water in the hydrous salt cannot simply be driven off without hydrolysis. Instead, it can only be prepared by reaction of finely-divided Fe metal with Cl2 gas, similarly to anhydrous AlCl3.

[Edited on 3-5-10 by JohnWW]

Satan - 3-5-2010 at 00:19

I thought that FeCl3.6H2O is suspectible to hydrolysis when trying to remove its water of hydration, not in solution, whats your source on this? Recently I dissolved Fe2O3 in excess 38% HCl, it didnt disolve until refluxing for 15min. I obtained from this very dark red solution, almost black. My book of inorganic preparations (Supniewski) says that I can safely boil it down without hydrolysis, to obtain FeCl3.6H2O.

JohnWW - 3-5-2010 at 01:50

I agree, Satan, although what would you use the stuff for in Hell?

12AX7 - 3-5-2010 at 04:47

On heating, it releases HCl fumes, and is in general quite corrosive; an excellent complement to brimstone?

Tim

bquirky - 3-5-2010 at 06:56

I (think) i made a few litres of ferric chloride a while ago.

I got a big old jar of scrap steel bits and HCL let the reaction run for a week filtered the solids and scum out. then took the jar outside into the hot sun and pumped air through it for another week.

the result after filtering out leaves and dead bugs was a dark brown/yellow solution with no aparant sediment or suspensions. That dissolved copper with ease so for my purposes I considered it ferric chloride.

I dont know if the sun is strictly necessary but i figured some UV cant hurt. and i sure didn't want that stuff bubbling away for a week making a mess of my work area.

IrC - 3-5-2010 at 08:08

Quote: Originally posted by JohnWW

I agree, Satan, although what would you use the stuff for in Hell?

Thanks a lot John. I laughed so hard I spilled coffee on my keyboard.

Satan - 3-5-2010 at 08:21

Quote: Originally posted by JohnWW

I agree, Satan, although what would you use the stuff for in Hell?

We etch PCBs for use in thermostats for human oil baths.

thorazine - 3-5-2010 at 09:46

Hey!
Thanks!
So many and different opinions.

When i evaporated to dryness i've got a paste that turn into a yellow/green powder. So, probably it is FeCl3.6H2O, right?

I took a photo:

Thanks!

IrC - 3-5-2010 at 10:32

I think you are incorrect. Read this link.

http://en.wikipedia.org/wiki/Iron(III)_oxide-hydroxide

Ok editing does not work. The () seem to cut off the board software creating a link. Just copy and paste it in another tab or window.

Study the chemistry in this link:

http://artmondo.net/printworks/articles/ferric.htm

Any time you are working in a water solution with ferric chloride you are going to deal with hydroxide formation not the desired chloride product you are looking for. Looks more like FDA approved Pigment Yellow 42.

Human oil baths? Wasn't that an old movie with Vincent Price?

[Edited on 5-3-2010 by IrC]

Panache - 5-5-2010 at 15:58

i'm sorry but does anyone one know what the fat rendered from a human is referred to (cf beef-tallow, pig-lard etc). Are you saying in hell they use this fat as an oil in 'human oil' baths or that they use oil baths for humans, like a swimming pool sized deep fryer in which humans are interned. If it is the latter what oil is used in this and how often is it replaced/cleaned? I have a friend who will pay well for used oil he makes into biodiesel.

IrC - 5-5-2010 at 17:53

So soylent clear instead of green or yellow?

The WiZard is In - 5-5-2010 at 18:40

Quote: Originally posted by Satan

We etch PCBs for use in thermostats for human oil baths.

Noted in passing. In industry ferric chloride solutions used to
etch copper are regenerated. For a brief description of the various
methods see —

William T Harris
Chemical Milling : The Technology of Cutting Materials by Etching
Clarendon Press - Oxford
1976

Satan - 6-5-2010 at 00:43

Quote: Originally posted by Panache

I have a friend who will pay well for used oil he makes into biodiesel.

We recover much of that oil, but we have agreement with almighty to only use this for purposes that helps us sustain our place - hell. And dont try to pm about that, if he knew about it I would pay huge fine, and I dont have money for it after insulating hell from surface, since it was partly causing global warming.

@The WiZard is In
Do you posses that book in pdf? I assume it would be interesting read for many if you can post it.

The WiZard is In - 6-5-2010 at 09:00

Quote: Originally posted by Satan

And dont try to pm about that, if he knew about it I would pay huge fine, and I dont have money for it after insulating hell from surface, since it was partly causing global warming.

Global warming is caused by American Daylight Savings
an extra hour of sunlight for six months is a lot of energy.

Any what ... a book sez —

It is also forms heating iron (III) oxide with HCl at elevated temperatures:

Fe2O3 + 6HCl --> FeCl2 + 3H2O

The product may be sublimed in a stream of chlorine to give
high purity grade iron (III) chloride.

The anhydrous chloride also may be made by heating the hexahydrate, FeCl6-6H2O with thionyl chloride:

FeCl3-6H2O + 6SOCl2 --> FeCl3 + 12HCl + SO2

Have put scanning recovery processes on the things to do list.

thorazine - 14-5-2010 at 12:53

Thanks!!

peach - 19-5-2010 at 03:15

I guess you already know, but you can buy FeCl3 for etching from electronics stores or online. I have a bag of it beside me now - it looks like some kind of alien cereal nodules, yum! Crispies!

It's a fairly similar color to your product, just darker and dirty yellow with a hint of green; although, even some of the newer digital cameras will butcher the color profiles of things so pictures aren't always a great indicator when color is involved. I remember having one of the first digital cameras and it ran from floppy disks

the amount of color and light distortion was horrendous! You didn't need to be in anyway picky to dislike the fact it could entirely change the color of something.

Back to the topic, I think others use peroxide and HCl.

I have a big tub full of the newer etch crystals, I think they're ammonium persulfate. They are nicer to use than the ferric etches, partly because you can actually see the board as it etches, so you can better judge when it's time to pull it out. Also, they seem to produce a finer, less aggressive etch, which is good if you're after clean, sharp edges on your boundaries; particularly important for the finer track work, where ferric will tend to eat random pits out of the sides and disconnect the tracks.

I haven't used the ammonium based crystals recently, but I think the solution was light blue. It was definitely far more transparent than the ferric method.

If you can, I'd avoid using ferric solutions. My 5kg tub of the ammonium crystals was only something like $20, and it'll last me a looooooooong time. 500g of the ferric crystals was about $8; 5 times less for half the price, and for a poorer option when it comes to PCB etching.

I think the aggressiveness of ferric solutions would be better reserved for more artistic etching, where you want to strip away a lot of material.

Remember that you can help nature out, keep etch costs and times down and even improve your circuit's efficiency by purposefully only etching away what needs removing to break the tracks and planes apart. If they have mains voltage on them, they still only need a quarter of an inch or so of separation from memory (Check that first! Particularly if humans may end up attached to the result via the bath).

[Edited on 19-5-2010 by peach]

thorazine - 19-5-2010 at 04:27

[Edited on 19-5-2010 by thorazine]