Sciencemadness Discussion Board

Path to tin(IV) sulfide?

Arcaeca - 28-8-2019 at 16:01

So I came across some 98% tin/2% silver solder at a hardware store today, and in my ongoing quest to make pigments from scratch I thought it might be neat to pick some up and try to make stannic sulfide, aka "mosaic gold", from it. Apparently this is usually done by bubbling H2S into an aqueous solution of tin(IV) salt, but unsurprisingly H2S is highly toxic, highly flammable, and not available at the local grocery store. Supposedly you can make it yourself (not that I have the equipment to do so safely) from FeS and HCl... which raises the question of where you get FeS.

Essentially, I don't know where I can get the sulfur atoms from, and even if I did, I don't know the path to synthesis. The only thing I can think of that contains sulfur would be easily available would be sulfuric acid drain cleaner (which usually has anticorrosives in it), but then somehow you'd have to strip all the oxygen atoms off the sulfate, which sounds like more work than it's worth.

(Or maybe I should just pick up some 60% tin/40% lead solder instead and burn it in air at 900 C, that's supposed to produce lead-tin-yellow, IINM)

Bedlasky - 28-8-2019 at 20:57

FeS is easily made by reaction of iron powder and sulfur. Reaction is highly exothermic.

Here is link to NileRed's video about it:

https://www.youtube.com/watch?v=NxAeQneITNA

[Edited on 29-8-2019 by Bedlasky]

Arcaeca - 28-8-2019 at 21:24

Okay, so... burn iron powder and sulfur powder to make FeS, then dissolve that in HCl to make H2S, which somehow has to make it into a solution with a tin(IV) salt.

So:


Twospoons - 28-8-2019 at 21:54

Even simpler you can use CaS instead of FeS. Goes by the name "Lime Sulphur" in the fungicide/bactericide section in your local garden store.

teodor - 28-8-2019 at 23:02

After oxidizing the solder in HNO3 add a soluble sulfide (Na2S) to the residue. It gives Na2SnS3 in solution. Upon addition of diluted HCl SnS2 will form. If you add to much HCl it dissolves again. The yield is not great, one should play with different concentrations to precipitate as much SnS2 as possible.

The better route to mosaic gold (I tried both) is directly from a tin (IV) oxide which is also cheap (in a calcined form). Take 3 parts Na2CO3, 3 parts sulfur, one part SnO2 , mix and fuse in a closed procelain cup until no more gases evolve and no more molten sulfur resides in the cup (I did it with an alcohol burner, it doesn't require high temperature). Possible some CO could evolve, not sure but be careful. You will get Na2SnS3 as a grayish-yellow powder, so dissolve the cup contents, filter, you will get all the sodium sulfostannate in the solution. Add 0.2M HCl and you will get mosaic gold as a dense paste (after vacuum filtration) but usually it will be orange-brown due to Sb impurities in almost any tin sample. For the purpose to get just a proper color add few drops of concentrated HCl to the Sn/Sb sulfide, it will change the colour instantly, possible dissolving all antimony sulfide first (H2S)! The SnS2 you'll get by this method is mixed with some sulfur.

Both cases use the same SnO2 -> Na2SnS3 -> SnS2 route but the chemical properties of freshly precipitated SnO2 and "calcined" are different, this is one of interesting things in a tin chemistry. You can use that one you make from a tin metal for fusing but that one you can buy doesn't fit for any water chemistry.

Getting chemically pure SnS2 is a bit more complex and possible really requires some H2S to separate from sulfur and traces of antimony. Also arsenic contamination is possible but I didn't find any visible amount in SnO2 which I bought in some pottery shop.

But think about addition of Na2S as an alternative to H2S, it works in some cases. Also, Na2S can be used for H2S generation if you can live with the H2S/CO2 mix (all Na2S contains Na2CO3 also, that's why people recommend to use FeS usually, which, as for my opinion, is not as easily to get as Na2S).

Hope it can help.


[Edited on 29-8-2019 by teodor]

Arcaeca - 29-8-2019 at 13:21

I mean, I'd rather use Na2S or CaS instead of H2S since it serms safer - although I can't find them for sale anywhere (I've checked 4 different hardware stores from 4 different companies and they all sell sulfates, but not sulfides). So I can get sulfur, but it looks like one way or another I'll have to prepare a sulfide from scratch.


Likewise I could make stannic oxide by burning tin metal in air, but at a temperature much higher than its melting point, so it would most likely solder itself to the crucible before turning into oxide.

teodor - 29-8-2019 at 20:01

There are a lot of possibilities how to make sulphides using just sulfur, check the forum, the topic was discussed several times. Chose a method which fits to your skills. I would do it by fusing NaOH and S.

Also I am not sure that sulfide and tin oxide are hard to buy, possible you just didn't find any supplier yet, but sure they exist.

You don't need a sulfide, please re-read what I wrote. You need tin 4 oxide, sodium carbonate, sulfur and hydrochloric acid.

[Edited on 30-8-2019 by teodor]

teodor - 31-8-2019 at 00:35

But if you have only a tin metal or alloy you should to oxidize it somehow (to IV valency). One method I wrote already - with a help of nitric acid . But you can try other oxidizers also. I would do an experiment trying to put pieces of tin into molten sodium or potassium nitrate, the same method as used to oxidize lead. See http://www.prepchem.com/synthesis-of-sodium-nitrite/ . I am not sure you will get SnO2 but think it worth to try.

Also, it could be possible to do SnO2, for example, by this route:

Sn -> SnCl2 -> Sn(OH)2 -> SnO -> SnO2

The last reaction, according to literature, could be accomplished by heating in air.

So, really, you can do a lot of interesting experiments trying to make SnS2.

[Edited on 31-8-2019 by teodor]

Arcaeca - 31-8-2019 at 09:20

Well, my problem is essentially one of supplies and equipment. I haven't been getting my chemicals from the nearest chemical supplier, since they only sell in much higher quantities than I need for prices I can't afford. Everything I've been working with so far is with stuff I can get at hardware stores or grocery stores, and my arsenal at this point includes:

And I've been doing everything in mason jars, since I don't have borosillicate beakers; they're not terribly heat resistant, although that can be improved somewhat by putting them in a sand bath... or at least that helped until I broke my propane burner, so it's a smidge hard to heat things now.

And that's really my problem with all the CaS synthesis procedures I've found so far - they either rely on chemicals I have no idea where to get other than chemical suppliers (e.g. nitric acid, alkali nitrates, iron powder, etc.) or equipment I don't have (e.g. airtight glassware for a safe H2S generator, crucible and furnace for the classic CaSO4 reduction to CaS, vacuum-sealed container for heating CaCO3 + S with as little oxygen as possible, etc.). Substituting sodium carbonate for calcium carbonate can only take me so far.

Basically making tin(IV) sulfide is two problems in one:

  1. oxidizing tin metal into solution as tin(IV), and
  2. getting (or making) a source of sulfide ions

And it's the sulfide that's the problem - I can't find a procedure that will yield a sulfide that I can actually do with what I have on hand or can easily get a hold of.

I've been looking through the forums for procedures for making CaS - there's one thread with lot of ideas but I'm hesitant to post a link since I think that triggered an auto-ban for me last time.

[Edited on 8-31-2019 by Arcaeca]

icelake - 31-8-2019 at 09:44

@Arcaeca: Just post thread id and post id (if necessary) of the thread/post.

Your current post for example:

tid: 153470
pid: 621757

Arcaeca - 31-8-2019 at 10:03

Gotcha. TIDs of the threads I've been looking at for making CaS are 153008 and 1245.

teodor - 31-8-2019 at 10:28

Quote: Originally posted by Arcaeca  


Basically making tin(IV) sulfide is two problems in one:

  1. oxidizing tin metal into solution as tin(IV), and
  2. getting (or making) a source of sulfide ions



So, the method I proposed for oxidation in the last post should work for you.

SnO - (heat) -> SnO2

To get SnO your set of chemicals/equipment could work. Try to convert your tin metal into powder (heat to 200 and smash), then study its reaction with HCl. The literature says it should be hot, but worth to try with powder.

(Another route is Sn + S (melting) -> SnS, SnS + 2HCl -> SnCl2 + H2S).
Quote: Originally posted by Arcaeca  

And it's the sulfide that's the problem - I can't find a procedure that will yield a sulfide that I can actually do with what I have on hand or can easily get a hold of.


But why you say you can't find it if I menthioned 2 such procedures already:

2 SnO2 + 2 Na2CO3 + 9 S = 3 SO2 + 2 Na2SnS3 + 2 CO2
Na2SnS3 + 2HCl = 2NaCl + SnS2 +H2S

4S+8NaOH = Na2SO4+3Na2S+4H2O


For heating just use old ceramic caps, even if it develop cracks it keeps everything inside.

Arcaeca - 31-8-2019 at 10:40

Quote: Originally posted by teodor  
But why you say you can't find it if I menthioned 2 such procedures already:


Because one of them required nitric acid, which I can't get, and the other required a crucible of some sort to put the sulfur and NaOH in while they're fused at high temperatures. I can probably pick up a simple propane torch from the hardware store, but I have yet to figure out where I can a crucible that can withstand that kind of heat - mason jars just won't do.

teodor - 31-8-2019 at 12:46

Quote: Originally posted by Arcaeca  

... and the other required a crucible of some sort to put the sulfur and NaOH in while they're fused at high temperatures. I can probably pick up a simple propane torch from the hardware store, but I have yet to figure out where I can a crucible that can withstand that kind of heat - mason jars just won't do.


Arcaeca, again, for SnS2 you need neither H2S nor Na2S. I mentioned Na2S synthesis if you curious but it doesn't related to SnS2.
Also, what do you mean by "high temperature". Please check the melting points of NaOH and S.

I wrote exactly this:
1. The reaction you can try is
2 SnO2 + 2 Na2CO3 + 9 S = 3 SO2 + 2 Na2SnS3 + 2 CO2

2. IT DOESN'T REQUIRE HIGH TEMPERATURE. I wrote I did it with an ALCOHOL BURNER. ALCOHOL BURNER and HIGH TEMPERATURE live in different worlds.

3. I did it in a CUP. I attached some pictures of CUPs. In the center is the one I used to make SnS2.

It seams you have everything you need and the information also. So, you definitely can try to make it. But be very careful with CO.



cups.jpg - 115kB


[Edited on 31-8-2019 by teodor]

Arcaeca - 28-9-2019 at 19:47

So okay, I think I have CaS from reducing CaSO4 (from plaster of Paris) with charcoal in a crucible. I just need a tin(IV) salt solution now. I forgot you can make SnO2 from SnO and so passed up the opportunity to buy SnO while I was at the pottery supply store earlier today, thinking it wouldn't work. I could make SnCl2 by dissolving my tin solder in HCl, but I don't think regular 3% H2O2 could oxidize it to +4, could it? Maybe 30% peroxide could but I'd have to get at least 500 mL from a chemical supplier and that tends to run >$100...

teodor - 30-9-2019 at 02:30

Arcaeca, I am not expert in tin chemistry (neither in other parts), just doing experiments with tin and antimony now. I wrote routes I tried already. We can try more routes to SbS2, but please, make a reference to some literature first. Tin chemistry is not so flat, for me it's better to study methods which work first and then make additional experiments, trying to modify them (which usually mostly fails).

So, which book about tin chemistry we can put as a theoretical background for the experiments?


[Edited on 30-9-2019 by teodor]