Sciencemadness Discussion Board - extract antimony from HCl

extract antimony from HCl

CHRIS25 - 22-4-2014 at 06:46

In the process of making Tin (2) Chloride and know that for every 100g of pewter I will have 8 grams of antimony in the HCl solution. A little bit of research seems to suggest that, for a kitchen chemist, extracting this is impossible, am I right?

bismuthate - 22-4-2014 at 07:06

Nope just add some zinc and a bit more HCL to the solution and burn off the escaping gas. At the bottom of the vessel you use you should have tin metal which can be dissolved in HCl. Be very careful this makes stibine gas.
Although the best thing to do would be to dissolve the pewter in HNO3 and filter off the antimony oxide. You should then have a solution of tin nitrates (which you should purify further via).

CHRIS25 - 22-4-2014 at 09:04

Then to be honest I do not want to go down there, I know that stibine is highly toxic. But thanks for responding.

blogfast25 - 22-4-2014 at 09:04

Quote: Originally posted by bismuthate

Nope just add some zinc and a bit more HCL to the solution and burn off the escaping gas. At the bottom of the vessel you use you should have tin metal which can be dissolved in HCl. Be very careful this makes stibine gas.
Although the best thing to do would be to dissolve the pewter in HNO3 and filter off the antimony oxide. You should then have a solution of tin nitrates (which you should purify further via).

Tin cannot make stibine gas (SbH3

.

Tin and antimony can be separated in various ways, none of which are particularly easy to do.

One way is to add copper wire to the solution: antimony (III) is reduced to Sb (0), which precipitates as a black coating on the copper: 3 Cu(0) + 2 Sb(III) === > 3 Cu(II) + 2 Sb(0).

Tin is not reduced by copper.

It's the basis of a forensic screening test for arsenic, which is also reduced by copper (but thus cannot be distinguished from Sb).

Of course then you'll need to separate the copper and tin.

Another ways is to dissolve the pewter in HCl, then add peroxide and KCl. On cooling K2SnCl6 crystallises out but the antimony remains in solution.

Quote: Originally posted by CHRIS25

Then to be honest I do not want to go down there, I know that stibine is highly toxic. But thanks for responding.

Trust me, the amount of stibine you'll be generating is so small it's negligible. If you've dissolved pewter in HCl you've in fact already made small amounts of SbH3!

But dissolving pewter in HCl is a real slow boat to China: you need nitric acid + HCl for that dissolution.

[Edited on 22-4-2014 by blogfast25]

CHRIS25 - 22-4-2014 at 09:10

But when the tin chloride has precipitated out of my HCl solution and I have filtered it off, I am left with antimony (8%) and copper (2%) in the HCl solution. Where is the point in adding KCl and Peroxide to get a potassium tin chloride precipitate, or have I misunderstood your explanation.

Missed your last, that's ok, heating it makes it go super fast.

[Edited on 22-4-2014 by CHRIS25]

blogfast25 - 22-4-2014 at 11:48

C25:

My turn to be confused now.

Have you (or not) dissolved pewter in hot HCl?

If 'yes', how did you precipitate out the tin chloride? By evaporative crystallisation? Or by some other means?

[Edited on 22-4-2014 by blogfast25]

CHRIS25 - 22-4-2014 at 13:32

Hi Blogfast, The reaction is proceeding without heating at the moment due to the weather, (it is under a bucket outside to keep out of the rain), I can only heat it when I am able to take my electrics and hotplate outside. I started it yesterday and it is already becoming milky. The tin 2 chloride hydrolyses in hot water, so I will keep the solution in a balanced state between warm and hot (subjectively) and have kept the HCl molarity to 7M and once again ensure an excess of HCl. I understand that SnCl2 will precipitate, as is now happening very slightly by the appearance of the milky white.

HgDinis25 - 22-4-2014 at 13:40

Quote: Originally posted by bismuthate

To produce any reasonable amount of Tin Nitrate a very low concentration of Nitric Acid ust be used. Usually, the reaction only yelds metastannic acid, wich readly decomposes to Tin Dioxide.
http://www.neymetals.com/tin.htm

Zephyr - 22-4-2014 at 16:20

Wait, am I missing something?
When I dissolved tin antimony solder with 30% HCl, a black crystalline solid was left behind.
I assumed this was antimony, because of antimony's resistance to acid.
I know wikipedia isn't a good source, but it says "Antimony is resistant to attack by acids."

CHRIS25 - 22-4-2014 at 23:35

Quote: Originally posted by Pinkhippo11

Wait, am I missing something?
When I dissolved tin antimony solder with 30% HCl, a black crystalline solid was left behind.
I assumed this was antimony, because of antimony's resistance to acid.
I know wikipedia isn't a good source, but it says "Antimony is resistant to attack by acids."

It is misleading, in the presence of Oxygen Anitmony dissolves. So in effect any solution that contains water (dilute acid) has oxygen and dissolves the antimony. As far as your solder is concerned I would imagine that the black is Tin. The actual colour being a thin oxidized layer since my pewter is blackened in the HCl solution while it is dissolving, actually the proper colour tin is actually black in cornwall and devon where they are famous for it.

[Edited on 23-4-2014 by CHRIS25]

woelen - 23-4-2014 at 03:41

I think I have to go with Pinkhippo11. In the presence of oxygen and chloride ions at high concentration, antimony dissolves in the acid as a chloro complex. But the oxygen must be free oxygen. Oxygen (as part of water molecules) does not dissolve the antimony.

Actually, many oxidizers can dissolve antimony, when also acid and chloride ions are present. Suitable oxidizers are oxygen (from air), hydrogen peroxide, chlorate ion, peroxodisulfate ion, chlorine, and many more. If no chloride ions are present, then antimony is much more difficult to dissolve.

bismuthate - 23-4-2014 at 03:49

blogfast I know that tin doesn't make SbH3 and did not indicate that it did. Oh now I see! Sorry.
You could try dissolving the alloy in CuCl2 or CuSO4 (which would be slower) then filtering it and treating the Cu/Sb with a acetic acid and H2O2 solution.
Or you could add sulfur and sodium sulfide to the solution and heat it to get a solution of sodium thioantimonate and solid tin sulfide I believe.
This page discusses separating Sn and Sb.
http://tin.atomistry.com/chemical_properties.html

[Edited on 23-4-2014 by bismuthate]

blogfast25 - 23-4-2014 at 04:13

Quote: Originally posted by bismuthate

blogfast I know that tin doesn't make SBH3 and did not indicate that it did.

C'mon bismuthate, read it again:

Quote: Originally posted by bismuthate

At the bottom of the vessel you use you should have tin metal which can be dissolved in HCl. Be very careful this makes stibine gas.

I know that was sloppy use of language but that's the problem.

@Woelen:

According to Holleman's 'Inorganic Chemistry', Sb dissolves very slowly in hot HCl, with formation of SbCl3 and hydrogen.

Quote: Originally posted by HgDinis25

Maybe but that must be the slowest way to produce a stannous salt imaginable. At least with HCl you can use 37 w% and refluxing, to speed things up. Even in those conditions, it's hardly fast, the last time I did it.

By far the best solvent for tin is Aqua Regia (even fairly dilute versions work well from my experience), in which it dissolves quickly. But that produces stannic chloride. Sb dissolves in it too.

[Edited on 23-4-2014 by blogfast25]

HgDinis25 - 23-4-2014 at 06:52

Quote: Originally posted by woelen

I think I have to go with Pinkhippo11. In the presence of oxygen and chloride ions at high concentration, antimony dissolves in the acid as a chloro complex. But the oxygen must be free oxygen. Oxygen (as part of water molecules) does not dissolve the antimony.

Actually, many oxidizers can dissolve antimony, when also acid and chloride ions are present. Suitable oxidizers are oxygen (from air), hydrogen peroxide, chlorate ion, peroxodisulfate ion, chlorine, and many more. If no chloride ions are present, then antimony is much more difficult to dissolve.

Actually, if you try to dissolve an alloy of tin and antimony in HCl, tin will react first because it is more reactive in the reactive series. Therefore, much of the HCl gets consumed producing Tin Chloride. After all Tin has dissolved there might be too little HCl to react with Antimony.
The black crystalline substance may very well be Antimony.

CHRIS25 - 23-4-2014 at 07:33

At this point I thought I would post this. This reaction is almost complete, it has practically stopped bubbling.
Pewter (For arguments sake Sn) +2HCl
26g (0.22mole) + 37mLs 11.6M (0.44mole)
as the reaction progressed I actually add more HCl to a total of 1.07moles.
This is the result, the black is a granulated mass unaffecetd by this very high concentrated HCl. (even with some HCl gas loss)

blogfast25 - 23-4-2014 at 08:25

Quote: Originally posted by CHRIS25

At this point I thought I would post this. This reaction is almost complete, it has practically stopped bubbling.
Pewter (For arguments sake Sn) +2HCl
26g (0.22mole) + 37mLs 11.6M (0.44mole)
as the reaction progressed I actually add more HCl to a total of 1.07moles.
This is the result, the black is a granulated mass unaffecetd by this very high concentrated HCl. (even with some HCl gas loss)

Yes, it's likely to be antimony. But note that this doesn't mean your SnCl2 solution is entirely, 100 % free of antimony.

Decant off the supernatant liquid and add quite some more HCl to the residue, as well as some H2O2. In my experience HCl + H2O2 dissolves antimony powder very effectively, to aqueous SbCl5. I've used this method in a synthesis.

[Edited on 23-4-2014 by blogfast25]

CHRIS25 - 23-4-2014 at 09:34

Yes I read one of your exhaustive posts filled with images of your experiment with tin, very interesting reading. But Why would I turn the antimony residue into antimony pentachloride? If I decant the liquid and boil this down, I should see SnCl2 precipitate out? And then just for fun turn the antimony powder into the metal by heating to 650c , I have never done this except with silver mud out of nitric acid, I presume this is possible with the antimony powder.

elementcollector1 - 23-4-2014 at 09:36

Quote: Originally posted by CHRIS25

Yes I read one of your exhaustive posts filled with images of your experiment with tin, very interesting reading. But Why would I turn the antimony residue into antimony pentachloride? If I decant the liquid and boil this down, I should see SnCl2 precipitate out? And then just for fun turn the antimony powder into the metal by heating to 650c , I have never done this except with silver mud out of nitric acid, I presume this is possible with the antimony powder.

Careful with oxygen - it's real easy to get antimony to oxidize. As I was sealing up an ampoule of pure antimony powder, an invisible amount on the neck (from pouring the fine powder in) turned into a thick white sheen of what is probably Sb₂O₃. In fact, you may have to do this under inert or even vacuum atmosphere...

CHRIS25 - 23-4-2014 at 10:23

I do not remember the reference but I am almost certain that I read that antimony is not easily oxidized? Actuallyu I am beginning to wonder whether I should just chuck it away? Having read quite a lot about this then to read this: http://cameochemicals.noaa.gov/chemical/2500

[Edited on 23-4-2014 by CHRIS25]

elementcollector1 - 23-4-2014 at 10:26

At room temperature? Maybe. At melting temperatures? Nope. Especially not with antimony powder.

blogfast25 - 23-4-2014 at 12:02

Quote: Originally posted by CHRIS25

Yes I read one of your exhaustive posts filled with images of your experiment with tin, very interesting reading. But Why would I turn the antimony residue into antimony pentachloride?

I was suggesting this only to confirm it is antimony. Of course it's not the only element that dissolves/is oxidised by HCl/H2O2 but in this context it would corroborate that the residue is Sb.

Sb is generally speaking not easy to oxidise in aqueous media, as evidenced by the reduction of Sb (III) by copper.

Oxidation of an element by direct union with oxygen is an entirely different matter: different enthalpies play a part. Antimony can be made to burn in air quite easily, for instance. That would make melting the metal powder without inert gas blanket difficult, specially for small amounts.

CHRIS25 - 23-4-2014 at 12:22

I am reading quite frequently that heating/burning antimony powder is dangerous. Can you confirm this?
It has to be antimony simply because I know the source of the pewter and its copper antimony ratio.

[Edited on 23-4-2014 by CHRIS25]

HgDinis25 - 23-4-2014 at 12:25

Heating/Burning antimony is going to produce Antimony Trioxide fumes that you shouldn't breath. Besides being the dust of a metal oxide, it is suspected that it has some carcinogenic potential for humans.

CHRIS25 - 23-4-2014 at 12:49

This is how it started - This is from wikpedia: """Pewter is an alloy made of tin mixed with antimony and copper. It is soft and flexible and it can be melted easily. It dissolves in hydrochloric acid to produce tin(II) chloride, leaving the antimony and copper behind in the hydrochloric acid."""
I thought it would be straightforward. I think I will ditch the antimony, no good drying it, see no real use for it, just thought I might add it to my metal collection.

Zephyr - 23-4-2014 at 14:21

The Merck index gives some more specific information regarding antimony and its resistance to attack by acid; "Not effected by cold dilute acids; attacked by hot concentrated H₂SO₄; readily by aqua regia. Nitric acid, depending on the concentration, converts it to antimonous or antimonic oxide. When finely divided it reacts with hot concentrated HCl."
In my previous experiment, when I filter off the antimony metal and evaporated the stannous chloride, which nice large crystals, I was left with a small volume of sticky liquid that would not crystallize. I now assume this liquid was antimony chloride.

CHRIS25 - 23-4-2014 at 14:57

Tomorrow I will be attempting to get the dihydrate SnCl2. The acidity is quite high so it should crystalize much more efficiently since it is extremely soluble in water, this should make the solubility of the SnCl2 not so high.

blogfast25 - 24-4-2014 at 10:11

Quote: Originally posted by Pinkhippo11

I now assume this liquid was antimony chloride.

No, it's concentrated SnCl2 solution. As C25 stated, it's very soluble in water and HCl. It just gets pretty viscous towards then end of the crystallisation.

It did that with mine, made from 99.9 % tin.

CHRIS25 - 24-4-2014 at 12:16

Excellent results. Stoichiometry calculations showed me that I could get my 0.19 moles of SnCl2 (deducted 10% from the Tin weight after weighing dry antimony powder) in 80mLs of soln down to 20mLs giving me a 9.5 Molarity, the soln is now at 35mLs so doing well, keep cooling it to check for precipiate then heating it again. The soln is now quite viscous, the perfect yellow tint colour. Anhydrous SnCl2 has a max molarity of 21M and the Dihydrate 12M. So if I reach 9.5M I think I will stop, since having the crystalized product will only mean that I will have to use more HCl to re-dissolve. I read that placing some tin into the air tight solution will prevent oxidation, but I do not think I need to do that with such a high acidic solution.
And yes I have 3.2 grams of antimony powder, have no idea what to do with it though, seems a bit toxic to go messing with from what I read.

[Edited on 24-4-2014 by CHRIS25]

blogfast25 - 24-4-2014 at 12:25

Quote: Originally posted by CHRIS25

And yes I have 3.2 grams of antimony powder, have no idea what to do with it though, seems a bit toxic to go messing with from what I read.

[Edited on 24-4-2014 by CHRIS25]

Use it to demonstrate another feature that distinguishes tin from antimony. Sb(V) compounds oxidise iodide to iodine, Sn(IV) ones do not.

Dissolve the antimony in strong HCl + H2O2, then simmer to reduce volume by at least half, to drive off/destroy any remaining excess H2O2. This solution (essentially HSbCl6 in HCl) will immediately cause iodine to form from iodide solutions. As said, Sn (IV) doesn't do that...