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Author: Subject: stannous chloride
palladiumdreams
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[*] posted on 25-11-2016 at 01:33
stannous chloride


I am trying make a 2M solution of stannous chloride and am getting left with a purple solution once all the tin is dissolved. I am positive that I am using 99% pure tin and 31% hardware grade HCL. I have not polluted the mixture with any precious metals. Any clue to what I may or may not be doing wrong?
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Meltonium
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[*] posted on 25-11-2016 at 05:11


The only thing I can think of would be a contaminant on your glassware. A stray permanganate crystal maybe? Or also, Tin chloride solutions oxidize in air to form another tin complex, so that might be happening.
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palladiumdreams
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[*] posted on 25-11-2016 at 18:25


Glassware was clean with no traces of precious metals or permanganates present. I checked the tin and it is rated as 99.9% pure. I'm at a loss as to why and it takes quite a bit of time to wait for the tin to dissolve.
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byko3y
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[*] posted on 26-11-2016 at 08:44


It's hard to understand what "purple" means. Just like dillute permanganate solution? Or maybe more like this? https://upload.wikimedia.org/wikipedia/en/b/be/Tin%28II%29_h...
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[*] posted on 26-11-2016 at 16:21


Just a long shot...:)

Are you sure you don't have 99.9% pure Titanium (Ti) and not pure Tin (Sn). It wouldn't be the first time someone mixed up the element symbols!

Titanium is grey and tough, Tin is bright and fairly soft.

Titanium dissolves slowly in HCl to give a distinct violet solution!
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palladiumdreams
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[*] posted on 28-11-2016 at 12:34


The color is brilliant purple like permanganate.
Very sure it is not titanium, the Tin melted on low heat. Where I bought it from offered an assay cert for the Tin
When I had my solution on low heat I had the lid 98% covered with a watch glass.

I would like to know what I have made and whether or not the solution is salvageable for another project. I know I can recover the tin metal at some point.
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Sulaiman
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[*] posted on 28-11-2016 at 13:17


I have 99.9% Sn and reagent grade HCl a few times with no pigmentation so no experience
but I'd start by boiling a sample of the HCl to dryness to get an idea of contaminants present.




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AJKOER
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[*] posted on 28-11-2016 at 19:24


An idea is that you may have formed a small amount of "purple of Cassius", which is created by the action of SnCl2 on a gold salt.

In other words, something you employed was previously used in dissolving gold and left a trace amount. In practice, SnCl2 is used to test for the presence of gold, and may have just found some.

For more background on SnCl2 see http://tin.atomistry.com/stannous_chloride.html , which is a compilation of historical extracts from chemistry journals over time.

[Edited on 29-11-2016 by AJKOER]
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palladiumdreams
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[*] posted on 29-11-2016 at 02:46


I figured I had "purple of Cassius" but I did not think silver (nitrate) would cause that effect.. To my knowledge there just is not gold or PGM present so I am still stumped.
Thanks for the link AJKOER

Is the tin chloride??? still useful for silvering mirrors as a reducing agent or should I just try and recycle the tin?
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Boffis
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[*] posted on 30-11-2016 at 10:46


What colour is your hydrochloric acid? Colourless or yellow?

I used to think that the yellow colour in hardware store 30% HCl was due to iron but to my surprise tests revealed that the iron content of the acid form our local hardware store is very low and the colour appears to be a dye. Who knows what colour it would turn if you try to reduce it.

Its easy now to buy high purity HCl so I no longer bother with hardware store grade material.
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woelen
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[*] posted on 1-12-2016 at 03:16


Add a little H2O2 to the purple solution. If it turns deep orange, then you have titanium in your solution, which in that case explains the purple color.



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palladiumdreams
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[*] posted on 6-12-2016 at 12:18


Thanks for suggestions people. Woelen's suggestion did the trick. I added a 3% solution of Hydrogen Peroxide and solution turned orange.
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gipo
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[*] posted on 19-7-2017 at 03:39


In Australia, Bondall Hydrochloric Acid contains a small amount of titanium dioxide <1% (for some strange reason) which turns any stannous chloride made with Bondall purple.
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MrHomeScientist
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[*] posted on 19-7-2017 at 07:03


Quote: Originally posted by Boffis  
I used to think that the yellow colour in hardware store 30% HCl was due to iron but to my surprise tests revealed that the iron content of the acid form our local hardware store is very low and the colour appears to be a dye. Who knows what colour it would turn if you try to reduce it.

I'm not sure that's correct. Iron(III) chloride is very strongly colored in solution, especially in solutions with high concentrations of chloride ions. See Periodic Videos' latest video on the World's Saltiest Water - a sample from that has a miniscule trace of iron, but it's still extremely strongly colored because of all the chloride.
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[*] posted on 19-7-2017 at 20:21


Quote: Originally posted by MrHomeScientist  
Quote: Originally posted by Boffis  
I used to think that the yellow colour in hardware store 30% HCl was due to iron but to my surprise tests revealed that the iron content of the acid form our local hardware store is very low and the colour appears to be a dye. Who knows what colour it would turn if you try to reduce it.

I'm not sure that's correct. Iron(III) chloride is very strongly colored in solution, especially in solutions with high concentrations of chloride ions. See Periodic Videos' latest video on the World's Saltiest Water - a sample from that has a miniscule trace of iron, but it's still extremely strongly colored because of all the chloride.


If you can, use sunny side HCl. It is colorless and probably very little impurities.
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