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Author: Subject: Tin (II) Chloride
MttLsp
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[*] posted on 19-7-2010 at 13:33
Tin (II) Chloride


Alright so I made some Stannous Chloride (SnCl2) by adding muriatic acid to lead free Solder Wire, which contained Tin and Antimony:
2HCl + Sn --> SnCl2 + H2
The reaction was ridiculously slow but if I cut up the Solder Wire into smaller pieces it would accelerate. Adding heat is out because a) HCl gas will be produced leaving me an excess of tin b) the stannous chloride may undergo hydrolysis and become Sn(OH)Cl or c) the antimony will decompose.

When I had a clear solution of tin chloride and hcl, I evaporated it by adding heat with an alcohol burner. I find this to be problematic since some of the SnCl2 might take on a hydroxide ion, as stated above. Is there a way to grow crystals from a stannous chloride solution that is slightly acidic using a seed crystal?

As a side note, I made my first piece of conductive glass out of a broken vase I had lying around. I heated the Stannous chloride to temperatures over 400 degrees C and let the gas, which contains Tin Oxide, make contact with a small piece of glass. The tin oxide formed a thin rainbow colored transparent film on the glass, and when I tested the resistance (2000k), I got readings as low as 0.08! Now I can make dye solar cells without spending 900 bucks on 50 slides of ITO glass. All I need is Solder Wire, Muriatic Acid, and a few microscope slides.


[Edited on 19-7-2010 by MttLsp]

[Edited on 20-7-2010 by MttLsp]
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Panache
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[*] posted on 20-7-2010 at 01:49


i think you may find that the hydroxide's of tin(II) have difficulty forming without any OH present, which is the case if you have excess acid, is this rainbow coloured glass the same as on older style high wattage spotting globes? i have one which is exactly as described.



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Eclectic
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[*] posted on 20-7-2010 at 03:46


You can use a ceramic crock pot To digest the solder and keep topping it up with Muriatic acid to get saturated SnCl2 solution. SnCl2 crystalizes just fine when this is cooled without any precipitate of SnO, as long as there is an excess of HCl.
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[*] posted on 20-7-2010 at 18:19


Quote: Originally posted by Panache  
i think you may find that the hydroxide's of tin(II) have difficulty forming without any OH present, which is the case if you have excess acid, is this rainbow coloured glass the same as on older style high wattage spotting globes? i have one which is exactly as described.


Yes I think it is probably the same material as your globe. And thanks for your input...I kind of figured that the Sn would have a hard time forming Sn(OH)Cl in the presence of acid. However I assumed that since the Hydrochloric Acid has a lower boiling point than that of water, hydrolysis of the Tin would occur after the HCl boiled off. But I did not take into account that the less concentrated the acid is, the higher the boiling point, and since the HCl reacted with the Tin it was a much lower concentration than when I first started, making it possible to evaporate it with heat. Once I get my temp. controlled hot plate I'll feel more comfortable doing this.

But hydrolysis occurs when a substance reacts with the Hydroxide ions in water right?
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cnidocyte
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[*] posted on 13-2-2011 at 09:09


I added some 20% hydrochloric acid (which I distilled from drain cleaner) to some lead free solder and let it stand overnight at room temperature but no reaction occured. Would adding some H2O2 help the HCl oxidise the tin?
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not_important
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[*] posted on 13-2-2011 at 11:07


20% hydrochloric acid is nearly the azeotropic (AKA constant boiling) proportions, doesn't fume when exposed to air,and boils around 109 C with the same ratio of HCl-H2O distilling off. It is concentrated enough that SnCl2 will not hydrolyse during concentration/evaporation.

Some of the Sb will go into solution with con hydrochloric, even in the cold. In an alloy a minor constituent (like the 5% Sb) is effectively very finely divided and reactions unimportant in bulk become significant.

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[*] posted on 13-2-2011 at 11:48


I've dissolved pure Sn in an excess of boiling 22 w% HCl, under reflux. It takes a while to do so, it's quite sluggish even at BP.

Obtaining the hydrate as a solid is a bit trickier. Carefully evaporate the excess HCl, maling sure you don't go too far or the SnCl2 WILL hydrolyse (happened to me!) SnCl2 is very water soluble sot it's hard to tell when to stop evaporating: stop when there's little liquid left, allows to cool and see if you get crystals (they may take a while to form). If not, evaporate a little further, and try again...

Alternatively use a combination of strong HCl and strongish HNO3 (the right combinations have been described in a few tin related threads on this forum).

Sn dissolves very, very quickly in this kind of ‘aqua regia’ but the nitric acid oxidises the tin to Sn [+IV], not Sn [+II]. Reduce this back with zinc (powder or granules) to Sn2+, then alkalise with strong ammonia (NH3). Sn will precipitate as Sn(OH)2.n H2O (stannous hydroxide) but Zn2+ remains in solution as Zn(NH3)2 (2+). Filter and wash thoroughly and the Sn(OH)2 is now the basis for most Sn [+II] salts, including the chloride, by dissolving it in the relevant acid…


[Edited on 13-2-2011 by blogfast25]
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cnidocyte
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[*] posted on 16-2-2011 at 15:30


Quote: Originally posted by blogfast25  
I've dissolved pure Sn in an excess of boiling 22 w% HCl, under reflux. It takes a while to do so, it's quite sluggish even at BP.

I tried refluxing the HCl solution and the solder turned black but didn't dissolve like I was expecting. The solder 99.3% tin and 0.7% copper.
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[*] posted on 16-2-2011 at 16:18


Quote: Originally posted by cnidocyte  
I tried refluxing the HCl solution and the solder turned black but didn't dissolve like I was expecting. The solder 99.3% tin and 0.7% copper.
What's your point? Tin dissolves in HCl. This is the standard production of stannous chloride. All the books have it written. Many of us have done it. No mystery here. Either you don't have Sn, you don't have HCl, or your HCl is too dilute. Fix your problem and move on. You have not discovered a new phenomenon in chemistry.
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[*] posted on 16-2-2011 at 19:06


I may be off but just an idea that I would look into if I wanted to try this(and I do soon because SnCl2 is used to give a luster oil slick appearence to glass and ceramic glazes) I would try to heat the Tin in H2SO4 in an attempt to form the sulfate then precipitate it as the oxide using either (aq)NH3 or NaOH. Reacting the precipitated SnO with HCl should produce SnCl2 and water by SnO + 2HCl => SnCl<sub>2</sub> + H<sub>2</sub>O.

I agree that it takes entirely to long to dissolve even with 35% H2O2 added. I did not try HNO3 yet however but I do need some tin salts to add to reduction firings in the kiln at 1200F because the look it creates is awsome.





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[*] posted on 16-2-2011 at 19:43


@cnidocyte it has got to be your hcl acid because i used 95% tin 5%copper powder dutchboy solder and it dissolved into a clear solution leaving a little bit of grey mud on the bottom. all i used as heat source was a scent candle warmer.the acid was industrial 33%. but does anybody know if the copper content will give me a false reading if i do a stannous chloride test on a gold solution?i heard somewhere that it would, but also isnt copper non reactive with hcl acid?
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[*] posted on 17-2-2011 at 01:34


The grey or black mud left after dissolving lead free solder in boiling muriatic acid is most likely the alloying metals in the solder, which don't dissolve unless you have oxidizing conditions, such as lots of air or H2O2.

I've made SbCl3 solution dissolving the residue from Sn/Sb solder digestion in HCl/H2O2.
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[*] posted on 17-2-2011 at 09:33


Quote: Originally posted by cyanureeves  
all i used as heat source was a scent candle warmer.the acid was industrial 33%. but does anybody know if the copper content will give me a false reading if i do a stannous chloride test on a gold solution?i heard somewhere that it would, but also isnt copper non reactive with hcl acid?


If any copper did enter the solution (as Cu++) your solution would be blueish/greenish tinged. In the absence of an oxidising agent HCl is a very poor solvent for Cu.

Quote: Originally posted by Eclectic  

I've made SbCl3 solution dissolving the residue from Sn/Sb solder digestion in HCl/H2O2.


Are you sure it was Sb (+III) and not Sb (+V)? In oxidising conditions Sb goes easily to +V. See also my thread on KSbCl6. Sb (+III) is easily oxidised by permanganate, so if your solution can’t discolour dilute KMnO4 then it’s likely to be H3O+ + SbCl6(-), rather than SbCl3…
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[*] posted on 20-2-2011 at 06:11


Quote: Originally posted by cyanureeves  
@cnidocyte it has got to be your hcl acid because i used 95% tin 5%copper powder dutchboy solder and it dissolved into a clear solution leaving a little bit of grey mud on the bottom. all i used as heat source was a scent candle warmer.the acid was industrial 33%.


I distilled the HCl myself and since HCl forms an azeotrope with water at around 20% I assumed thats the concentration but I don't know the concentration of HCl in the drain cleaner I distilled it from so I'm guessing its under 20% so I need to redistill to up the concentration.
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[*] posted on 20-2-2011 at 06:18


@Blogfast:

Could be, but I had slight excess of the Sb mud which should keep the valence at III. All I was really aiming for was Sb dopant for the SnCl2 solution, which is also reducing.
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[*] posted on 20-2-2011 at 11:04


Yes, with an excess Sb you're likely to stay at +III.
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[*] posted on 12-3-2011 at 12:03


To say that the process of producing SnCl<sub>2</sub> with 32% HCl and metallic tin is slow is a formidable understatement!

About 10 days ago, I decided to get rid of a spool of tin/silver solder I've had for a long time (96% tin/4% silver)

Knowing that tin chloride is a reducing agent that helps precipitate the silver in metallic form, I figured that I would snip off the solder in small 2mm bits (20g), put that in a flask and pour 100 ml of HCl and i would have a lovely solution of tin chloride and some metallic silver at the bottom and i'd be done with that...

Not so! It's been 10 days and after some effervesence during the first few days, the reaction has been slower and slower until it's just dark grey bits that have barely dissolved, and a very modest pinhead-sized hydrogen bubble once in a while. At that rate, it will take a billion years to completely dissolve. I've even put that on the hotplate at low for a short while and it did effesversce vigorously, but not much dissolution of the metal bits in the flask...

I tested the pH of the solution and it's still strongly acidic, so I haven't run out of acid, it looks like the metal has mostly passivated :o could this be caused by the silver?

Oh, and my acid is indeed 32% HCl and the solder according to the Kester data sheet specifies the correct amount of tin vs silver. Could it be that the rosin core of the tin solder affects the reaction? I have not the ghost of an idea what is in that rosin, only that it says it's not recommended for electronics.

Robert





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blogfast25
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[*] posted on 12-3-2011 at 12:06


Robert:

Forget doing this without heating: at reflux with 32 % HCl progress is reasonable, at RT it's the slowest boat to China.

Remember they used to coat the inside of tin cans with tin for a reason!

[Edited on 12-3-2011 by blogfast25]
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[*] posted on 12-3-2011 at 12:18


Okay then, I guess i'll pull out the ol' vigreux, which happens to be 24/40 like my flask, and put it to good use. i'll set the hotplate at low, and leave it runing for a couple of hours. Thanks blogfast25!

Edit: Here's my setup:



I added a bubbler at the top of the vigreux, with a flask full of NaOH to avoid any rogue gases from filling-up my lab.

Robert


[Edited on 12-3-2011 by Arthur Dent]




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blogfast25
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[*] posted on 12-3-2011 at 14:07


In a few hours the SnCl2 should be yours... Mwhahaha...
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Arthur Dent
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[*] posted on 26-3-2011 at 11:02


The tin chloride synthesis worked fine, after decanting the solution, I got lovely pure white crystals. After refluxing and boiling the solution, I was left with a very fine dark gray dust at the bottom of the flask.

Remember: My original compound was Kester tin solder 96% tin - 4% silver.

So that fine, totally insoluble dust (even in hot 32% HCl) must be silver, right?

So I decided to thoroughly wash the dust with distilled water (4 times to make sure no traces of Cl compounds are left). and then I added some nitric acid to the wet slurry at the bottom of the flask. After some angry orange fumes, I was left with this:



What gives? Silver nitrate is supposed to be a colorless solution, and even if there were tin traces left, stannous nitrate is supposed to be colorless too, right?

So I had this turbid light purple solution that settled overnight to a slightly cloudy clear supernatant liquid with a very generous light purple precipitate.

Could this be caused by another metallic contaminant, or traces of chloride? The HNO<sub>3</sub> is 42be lab grade stuff.

Robert






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[*] posted on 26-3-2011 at 11:12


Try again. I feel you didn't use enough nitric (what's the w% of 42 Beaume?) and what you have is partly reduced AgCl (it's very light sensitive - OBVIOUSLY). Filter off or decant off the supernatant, then add good dollop of nitric, until ALL dissolves. Heat a bit if needed. OUTSIDE!

Show us the crystals of SnCl2?

[Edited on 26-3-2011 by blogfast25]
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Arthur Dent
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[*] posted on 26-3-2011 at 12:02


42 Beaume is approx. 67% which is fairly concentrated. I added a good 10 ml to the silver residue which looked like just a small sprinkling of dark dust. Didn't measure it but to the eye, it was something like 1 g or less. Okay I'll try to add a bit more nitric acid to see if it dilutes the remaining gunk.

Robert




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[*] posted on 26-3-2011 at 13:56


Ok, 67 %, that's the 'real deal' (wish I had me some of that!)

Remember, AgCl is seriously insoluble (it's used as a gravitational lever in the wet analytical determination of silver - old style). So your acid has to carry out a displacement: AgCl(s) + HNO3(aq) --- > AgNO3(aq) + HCl(g).

Any NOx evolved is due to some AgCl having been photo reduced to Ag + 1/2 Cl2, the metal then reacts with the nitric, giving off the usual witches' brew.

Your purple insoluble really looks like AgCl that's seen just a bit too much light. T'is really the Dracula of chemical compounds!
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[*] posted on 27-3-2011 at 06:27


Quote: Originally posted by blogfast25  
Ok, 67 %, that's the 'real deal' (wish I had me some of that!)

Remember, AgCl is seriously insoluble (it's used as a gravitational lever in the wet analytical determination of silver - old style). So your acid has to carry out a displacement: AgCl(s) + HNO3(aq) --- > AgNO3(aq) + HCl(g).

Any NOx evolved is due to some AgCl having been photo reduced to Ag + 1/2 Cl2, the metal then reacts with the nitric, giving off the usual witches' brew.

Your purple insoluble really looks like AgCl that's seen just a bit too much light. T'is really the Dracula of chemical compounds!


Yeah, I agree that there was probably much more Silver Chloride than elemental Silver at the bottom of my flask before I added the Nitric acid. I'll filter the solution and save the filtrate and i'll try to see if I can react some of the dried precipitate with fresh HNO<sub>3</sub> to further dissolve that stuff.

Robert

PS: Oh and the acid, I bought a 2.5l glass bottle over 25 years ago from Anachemia, still more than 3/4 full. Has lost nothing of its potency and still perfectly clear and colorless! :)

PPS: Here are the tin chloride crystals... I dropped a few drops of the saturated solution on a watchglass and let dry for a couple of hours. Lovely needlelike crystal lattice!




[Edited on 27-3-2011 by Arthur Dent]




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