Make Iron (II) and (III) Chloride

Here I demonstrate how to make iron (II) chloride, convert it to iron (III) chloride, and then regenerate it back to iron (II) chloride. We'll be needing both of these reagents in an upcoming video.

Very simply, just add some steel wool to hydrochloric acid to produce iron (II) chloride and hydrogen gas:
Fe + 2HCl == FeCl2 + H2
The finer the wool, the faster the reaction will be.

Iron(II) chloride is rather unstable, and will readily oxidize to iron(III) chloride if left out uncovered. This reaction requires hydrochloric acid, but even so I've heard it's extremely hard to keep iron(II) chloride for any length of time.
4FeCl2 + O2 + 4HCl == 4FeCl3 + 2H2O
This reaction can be sped up greatly by introducing oxygen directly into the solution, using 3% drugstore hydrogen peroxide.

Finally, iron(III) can be converted back to iron(II) by adding in some more steel wool. Over a few minutes, this causes the solution to change color from brown back to lime green.

[EDUARDO]

Thanks for the upload, Iron(III)chloride is one of the solutions I need to make to detect bisphenol, as you may know this stuff is almost everywhere in plastics.

[BassheadCurry]

I would describe the "green yellow" color as Chartreuse.
i guess because im a fisherman. and chartreuse is a highly popular color in baits.
nice video, i learned the science and you learned the color! i learn something every day.

[mrhomescientist]

Generally when you get a cloudy brown solution working with iron salts, you've made iron hydroxide. Iron salts like to decompose to the hydroxide or oxide easily, and heat would accelerate this. You could try slow evaporation instead. Your steel might possibly have extra impurities in it that could interfere.

[mrhomescientist]

Yes this is my house. I actually turned one of my spare bedrooms into a dedicated lab! If you don't have a separate lab space, it's probably best to do your experiments outside (and for many experiments, it's required anyway). I'd strongly advise against keeping chemicals in the same room that you sleep in. See if you can set aside a work space in your garage, maybe.

[mrhomescientist]

@mitpatterson Yep, and that's all you need! I recommend you do it outside, because mine smelled really bad while it was dissolving. This method is a great way to make your own PCB etchant for much cheaper than buying it. After you leave the green iron(II) out and it's fully converted to brown iron(III), it's ready to etch!

[mrhomescientist]

@Gta2CubanPete You're right about the crystals, it's near impossible to keep nice green iron(II) crystals without them oxidizing (from what I hear). I'd try putting it in mineral oil to keep it away from oxygen, like you would for sodium. I'm going to use mine to make ferrofluid in my next video, so I'm just going to use the solutions directly. Thanks for the comment, and good luck with your own synthesis!

[michaelliangzhu]

i find your demo very interesting . at least my chemistry student would be inspired to see the vids here .

[mrhomescientist]

@GiorgioCapocasa Yes I've heard of that before too. That should work! Eventually though, you will get a large volume of etching solution as you continue to dilute it when you regenerate with acid (usually 32%) and peroxide (usually 3%). 30% peroxide would be better, so you're not adding as much water. It might be cheaper to just throw it away and buy new though, depending on what your reagents cost. Good luck!

[abdellahgogop]

I have 34° baumé hydrochloric acid, what is the percentage of it??? With the temperature =25°C.

[JonathanFosdickNano]

I too had some steel wool and had it soaking in hydrogen peroxide. Upon the addition of HCl it turned dark amber in color, adding more HCl the solution turned to a bright yellow color and was rather exothermic (>150F) and placed it outside in the cold (near freezing temps) and left it for apx. 30 min... to my surprise it turned completely clear. Upon the addition of 35% hydrogen peroxide it turned amber in color and I'm convinced it was Iron(III) chloride. What state gives it a clear color?? On a side note, it is night here.

[jhyland]

Hey, did adding the HCl to the steel wool smell terrible? I just did this and it turns out that some sulfur impurities in the steel wool cause H2S to form, which sucks... lol

[Jamal]

Yeah, thats exactly what i was using. Now i bought some 00 superfine steelwool which seems to be the right stuff since it produces the the nice green solution shown in the vid (besides a real bad smell and a bunch of garbage)

[yuriyfazylov]

I made a dry mix of Fe(II)Cl3.6h2o and but it turns out I needed Fe(III)Cl3. I knew it going forwards with the mix, as my lab didn't seem to have Fe(III)Cl3. I followed a recipe, that was for some cell cultures.

@mrhomescientist Would you suggest just let the mix get some air to become Fe(III)Cl3 once in water? My mix is acidic. Fe(III)Cl3 would just be a micro component for the growth media.

Edit: did you try to crystallize the Fe(III)Cl3 you made in the video? I assume it's molarity would be easier to calculate going from dry form back to hydrated form.

[LUMINARIASFOTON]

Sabrás alguna manera sencilla de hacer fe3o4? Este oxido es fabuloso por ser reversible su estado de oxidacion, por ende es excelente para hacer baterias.
O me equivoco?
regards ;)

[mrhomescientist]

Sure, if you want crystals. FeCl2 is much harder, because it easily reacts with air to change to iron(III).

[Azuris]

What is the reaction equation of producing Iron(II)-chloride solution from Iron(III)-chloride solution?

2FeCl3 + Fe = 3FeCl2

It is correct? I think that the Iron(II)-Chloride are generated by the pure Iron oxidizing with Iron(III)-chloride. But please correct me if I wrong!

[antexp]

Hi nice video thank you. I have made a iron electroplating bath using iron sulphate + ammonium sulphate and hcl. It is a pale green/white coloured solution. Does it make sense that this would be iron2 chloride?

[CampbellChemistry]

cool vid, what is ferric or ferrous chloride used for?

[nikushim]

If you have the HCI sitting around just use H2o2 and HCI, its alot cheaper then feci3 and the byproduct of cuci2 can also be used as a etchant

[Andellius]

My solution turns green instead of yellow. Does your sulution have hydrochloric acid left or is there something else changing the colour?