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Author: Subject: Stannous Chloride - An Idea
m1tanker78
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[*] posted on 1-4-2011 at 17:10
Stannous Chloride - An Idea


I've been wanting to make some tin chloride using lead-free solder for a while now but have been discouraged by various claims that it takes a long time even at elevated temps. To add to the discouragement, I believe my solder (solid core) to be 60/40 tin/zinc. I'll need to take a look at the MSDS again but I got to tinkering today and have something I'd like to try....

I took roughly 60/40 solder/sodium metal and slowly melted them together. I wasn't sure what would happen so I did this with an inverted soda can (yeah - I know, I know). The two readily joined once molten. After the alloy cooled, It began to slowly react with the moisture in the air rather uniformly. It formed a thin black crust on the outside which I assume is a mixture of aluminum impurity and the sub 1% metals which are alloyed with the solder. I treated the alloy with some water at which point it bubbled happily but nowhere near 'violent'.

Now, I'm left with a couple of questions. First off, could this alloy be treated with an excess of HCl to yield the chlorides of sodium, zinc and hopefully, tin? The idea here is that the sodium should quickly react with the acid and form some tiny voids or channels - a Raney Nickel of sorts. From there, zinc should follow in reactivity and hopefully leave tin with a much larger surface area (the bubbles may interfere or may provide a little agitation within).

My other question is how much interference, if any, would zinc chloride create if I wanted to deposit a tin oxide coating on glass? I'm not too worried about the sodium chloride. I think it would be nearly impossible to separate the chlorides of zinc and tin - especially with my crude equipment.

What do y'all think?

Tom
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[*] posted on 2-4-2011 at 08:30


If you created a true alloy (Na, Sn, Zn) then in all likelihood it will dissolve quickly and completely in HCl, yielding a mix of the chlorides. But it seems a wasteful way of doing it: using strong HCl (>= 30 w%) and heat, dissolving Sn/Zn (or even pure Sn) really doesn’t take that long.

Sn and Zn will co-precipitate with alkali to their hydroxides. Add too much alkali and both will redissolve resp. as stannite anion and zincate anion (known as amphoterism).

But if you added the right amount of alkali (here even soda will do!) both hydroxides precipitate and can then be separated with strong ammonia (NH3): zinc forms an strong, water soluble ammonia complex (Zn(NH3)2 (2+)), Sn doesn’t (and remains as solid Sn(OH)2.2H2O). Alternatively, neutralise the acid solution of Sn and Zn (and Na) and neutralise with strong ammonia: Sn will precipitate as Sn(OH)2.nH2O, Zn and Na remain in solution (Zn as the ammonia complex)
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Arthur Dent
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[*] posted on 2-4-2011 at 12:58


Hey Tom!

That's an awfully circovoluted method of making Tin Chloride! I would probably start looking for an alternative source for tin instead.

I recently made Tin Chloride with solder too, but my alloy was 96% tin and 4% silver, which was much easier to separate than Zinc and Tin chloride. Plus I wouldn't go wasting some hard-to-find metallic sodium as blogfast25 mentioned.

Go to a welding supply shop, you'll be able to get 100% pure tin there, plus loads of other metals, chemicals and even compressed gases in cylinders!

the process is long, but if you have a decent refluxing apparatus, you can heat the tin with concentrated HCl and within 3 to 4 hour, the tin will have almost completely dissolved (add an excess of tin if you want your Tin Chloride to be free of any traces of HCl). When your tin stops effervescing, you can assume the process has completed and after that, all you need is to cool down your remaining solution and either let it dry in a vacuum dessicator (that's what i've done), or freeze it (haven't tried that) and when it crystallizes, you got your stuff!

But definitely dude, go get a better source of tin, I swear, it's quite easy and tin is rather inexpensive. Check this site! : http://www.espi-metals.com/metals/catTinIngot.htm

Robert

[Edited on 2-4-2011 by Arthur Dent]




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m1tanker78
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[*] posted on 2-4-2011 at 18:31


Blog, concentrated ammonia solution is out of my reach at the moment. I think the janitor supply places stock only the variety that contains surfactant. It would be a neat experiment for curiosity's sake if nothing else.

Robert,
Quote:
Plus I wouldn't go wasting some hard-to-find metallic sodium as blogfast25 mentioned.


Let me turn that around on you. What good does metallic sodium do sitting in a jar of oil?? :P :D Sometimes I'll extract a little bit of Na metal as a by-product of some experiments I do with molten salts. The only use I have for it right now is hands-on answering some of my thousands of "what ifs". The alkali metals have always fascinated me for some reason.

Pure tin at the welding supply shop? I'll check with the place where I buy my welding supplies to see if they have any. Unfortunately, I don't even have a mundane reflux app so that's out of the question right now. Espi Metals won't do business with individuals :mad: but I'm sure there are a number of other places that will sell reasonably pure tin.

Next time around, I'll try a lower % of Na and try to make a little video if anyone's interested.

Thanks for the pointers!

Tom
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Arthur Dent
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[*] posted on 3-4-2011 at 05:59


Quote: Originally posted by m1tanker78  
Let me turn that around on you. What good does metallic sodium do sitting in a jar of oil? (...)The only use I have for it right now is hands-on answering some of my thousands of "what ifs". The alkali metals have always fascinated me for some reason.


Touché! ;)

You're right, if youze got it, use it! LOL As much as I am starting to have a pretty decent lab, and have been dabbling in chemistry for the past 25+ years, I've never even seen real metallic Sodium! It's one of those "out of my reach" components for me at the moment. The only alkali metal I have is a bit of dirty metallic Lithium from batteries.

So you can imagine i've been very eager to try out the metallic Potassium synthesis experiment (still waiting on my order of KOH).

As for a reflux apparatus, you can probably conjure up something that's very simple. Take any boiling flask, put a stopper with a hole and insert a long glass tube flush with the hole in the stopper. Wrap the tube with a wet rag and hold it together with some garbage bag ties, voila! Keep the rag humid throughout the refluxing process with some cold water, make sure the cold water doesn't drip on the flask or you might have unexpected breakage. :o

Just make sure you do this in a well-ventilated area because some gases might escape and HCl vapor is very unfriendly with tools and metallic stuff in gereral... and lungs!

good luck with your quest for Tin! :)

Robert






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[*] posted on 3-4-2011 at 06:08


"What good does metallic sodium do sitting in a jar of oil??"

Fair point, I guess. ;)

You can easily make fairly strong NH3 by dry distilling NaOH with any ammonium salt in an 'apparatus' cobbled together in about 15 min from things around the house: NH4X (s) + NaOH(s) + some warming (optional) === > NH3(g) + NaX(s). Crude ammonium sulphate from most garden centres. Capture the NH3 gas as you would any extremely water soluble gas. There's info about it on this forum (search for 'ammonia' by 'blogfast', that should do it).

And when I think about it, janitorial ammonia (about 4 %) would probably perform the above trick too...


[Edited on 3-4-2011 by blogfast25]
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[*] posted on 3-4-2011 at 09:31


Quote: Originally posted by m1tanker78  
I'm sure there are a number of other places that will sell reasonably pure tin.
Like Rotometals.
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[*] posted on 3-4-2011 at 10:49


I highly doubt your solder is 60/40 tin zinc. Even for aluminum soldering, this is way too much zinc to be able to flow at all.
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[*] posted on 3-4-2011 at 12:16


Quote: Originally posted by smuv  
I highly doubt your solder is 60/40 tin zinc. Even for aluminum soldering, this is way too much zinc to be able to flow at all.


Yep, you're right on the money. I looked up the MSDS and it seems the composition is ~95% Sn, ~5% Cu, and a ridiculously small % of Se. I don't know why I was under the impression that it had a high zinc content...

Will the Cu settle out as a suspension or will it settle at the bottom once the tin is digested by the HCl?

Tom
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[*] posted on 3-4-2011 at 12:19


I've been looking into stannous chloride recently myself. Read Robert's posts with interest. I hope to use it to confirm the presence of precious metals. The fastest way for me to get my hands on some tin was to take suggestions from elsewhere to look into non-lead weights for fishing lines. Price is drawback if you wanted a quantity. Also not sure of the makeup; in a sense the issue has moved from identifying gold to identifying tin ;). It's quite a soft metal.
I dropped around .6g into 5ml or so muriatic acid in a test tube close to two weeks ago and left it to see what transpires. I'd say that around .5g has been digested at this point with occasional warming.




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[*] posted on 3-4-2011 at 12:48


It is very easy to make stannous chloride from that alloy, just cut the solder to small pieces and dissolve it in ~15-20% HCl, but interrupt the digestion of the solder when say 75% of the solder has been digested (filter out the solder). In this way your solution will contain VERY little copper (so long as unreacted tin metal remains).

I also recommend, before posting really crazy ways of trying to do things, you do a quick google books search, old manuals have really great monographs about most simple organic salts. Just read the monograph about the metal you want, and about the other impurities in the base metal and you should be able to come up with a reasonable purification scheme.
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[*] posted on 3-4-2011 at 13:37


smuv, I usually burn up google before I post a question here. When I get nothing but pay-per-view scientific papers and unrelated stuff, it's time to ask someone in the know. I love reading old texts on google books, BTW. I'll try your suggestion but give me an idea of about how long it takes.

food, Robert's posts are great but I have no reflux app. I might try my hand as per Blog's suggestion. It'd be nice if the tin weights contain impurities that are easy to get rid of or hardly any impurity at all (not likely). Check the link that Watson posted above..

I went ahead and dropped the little solder/sodium nugget I made into some concentrated HCl. I'm checking it every 5-10 minutes or so to see how it's coming along. It's approximately 1 gram of alloy in ~35mL of 33% HCl.

Tom
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[*] posted on 3-4-2011 at 21:11


Quote: Originally posted by m1tanker78  


food, Robert's posts are great but I have no reflux app. I might try my hand as per Blog's suggestion. It'd be nice if the tin weights contain impurities that are easy to get rid of or hardly any impurity at all (not likely). Check the link that Watson posted above..


Hi. I'm assuming that the weights will work out as recommended, and that crystallizing the product may clean things up a bit. It's just something on the backburner right now anyway. In fact, it's not even on the burner it's at room temperature.




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[*] posted on 4-4-2011 at 07:13


It took about 45 minutes for the HCl to completely digest the tin/sodium at ambient temperature (~27*C). There was a black porous mass left of what was the alloy nugget. I gently poked it to make sure there wasn't any tin in the center and it crumbled apart. All of this stuff stayed at the bottom so I was able to easily decant the liquid which is still a little acidic. The liquid seems a little more viscous compared to water and is crystal clear. I expected to see a slight green or aqua tint - especially since I let it sit overnight before decanting.

Like I mentioned before, the volume ratio of solder:sodium was about 3:2. This means that the w/w ratio was about 6:1 solder/sodium. Even then, I believe I used more sodium than was needed to accomplish this task. I treated the alloy with water prior to this experiment so the ratio of what I put in HCl should be higher. I expect the resulting ionic ratio to be similar.

I'll follow Blog's advice for evaporating and see if I can get some crystals...

Tom
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[*] posted on 5-4-2011 at 08:01


Tin(II) chloride crystals with copper chloride impurity from the leftover solder residue:



IMG_3045(2).jpg - 217kB

Edit: Corrected crystal composition.

[Edited on 4-5-2011 by m1tanker78]
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[*] posted on 5-4-2011 at 08:52


Looks good! :D
Tin chloride crystals and copper chloride crystals both develop into beautiful needle-like structures,

In the photo below, I prepared a solution of tin chloride, I put a few drops in a watchglass and let it dry at room temp for a day or two. They are relatively pure tin chloride that show the needle-like crystals.



Copper chloride crystals are a very deep, intense green, so your crystals above might be a combination of copper chloride and tin chloride judging by their pale color.

Robert




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[*] posted on 5-4-2011 at 10:07


Robert, I'm a little envious of your tin chloride (for good reason)!

The crystals in my above pic are indeed a combination of Sn and Cu chlorides. I left 2-3 mL of tin liquor behind when I decanted. These crystals are the dihydrate, right? I love how nucleation randomly takes place and can clearly be seen in your crystals.

Unfortunately, a few grains of crud wound up in my decanted solution so it's now turning green. I'll be more careful next time and probably filter instead of decant and just accept a little loss in the filter paper.

What did you do with your silver solution or suspension after all?

Tom
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[*] posted on 5-4-2011 at 17:20


My purple silver goo is still in its little stoppered test tube. I might experiment further with it this weekend.

As for the tin chloride, it is the stable dihydrate. In its solid form, it is a slightly hygroscopic white solid and keeps better if there are traces of HCl left in the crystals. It's a long process to dry a large quantity, but it can be kept infinitely and if you need to use it for precious metal detection, just dissolve a few crystals in a little cold water with a few drops of HCl and you'll be good to go!

Robert




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[*] posted on 8-4-2011 at 12:40


Quote: Originally posted by Arthur Dent  

As much as I am starting to have a pretty decent lab, and have been dabbling in chemistry for the past 25+ years, I've never even seen real metallic Sodium! It's one of those "out of my reach" components for me at the moment.



Robert, if you don't mind me asking, is it because of the cost of ordering Na or is it because it's regulated where you live?

I sent you a PM...

Tom
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[*] posted on 8-4-2011 at 14:37


Hey Tom,

Yeah, the metallic sodium is outrageously expensive at most chem suppliers (so is K) and my budget being modest, I concentrate mostly on OTC chems, and go to the suppliers only for the exotic compounds I really really need.

There are certain regulations in Canada, mostly for chemicals that are explosive precursors, like HNO3 and various nitrates, but it's not as stringent as what some of our members discuss in various "restrictions" threads.

As for potassium, I'm really eager to get my order of KOH and try ot the cool german experiment everyone has been having fun with!

Robert





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[*] posted on 8-4-2011 at 16:06


Quote:
As for potassium, I'm really eager to get my order of KOH and try ot the cool german experiment everyone has been having fun with!


You mean the sticky on the general forum? I hope you make some K and "turn that alkali frown upside down." :D

If you have a DC welder and you're comfortable around molten salts, that could be a very viable and cheap way to obtain some Na (not sure about K - haven't tried yet).

Tom
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