SnCl2 crystals

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Bluebloomer

Well-known member
Joined
Jul 7, 2014
Messages
140
Location
Netherlands
Hi all, I bought some SnCl2 crystals 99,8% from a chemical store. I tried to dissolve a few grams of the crystals in 35% HCL. I heated the solution before adding the crystals. When the crystals all dissolved I added some more until noting dissolved anymore, only a few crystals remain on he bottom of the beaker.

Once the liquid cooled down, I had a huge pile of crystals on the bottom of the beaker. It looks like the HCL dissolved the crystals when hot, but most of the crystals reprecipitated when cooled down. How is this possible, and what is going wrong ?

I thought it was straight forward to dissolve some of the crystals in HCL and have a ready to go stannous chloride testing solution, but this liquid is not showing a positive for gold.

Also, I wanted to melt some tin figurines and pour it into shot so I can add it to the stannous chloride, but first I have to know (and understand) what is going wrong. Can anybody explain it ?
 
Warm it back up and add more hcl.
The solubility of sncl is greater in a hot solution than a cold solution. The solution you have was saturated while hot and once it cooled the solubility of sncl became less so it precipitated from solution.
 
I guess you can use SnCl2 crystals to test for gold.......... :)
watch this video ............
https://www.youtube.com/watch?v=jnVSkgJ0Dxc
 
goldfever007 said:
I guess you can use SnCl2 crystals to test for gold.......... :)
watch this video ............
https://www.youtube.com/watch?v=jnVSkgJ0Dxc

He has now introduced tin into his gold. Not a very good situation when striving to reach 99.99.
 
I agree with Shark. That was foolish. To test a solution you remove a drop and test it with stannous. You don't dump a bunch of stannous into your beaker of pregnant solution.

Dave
 
Thank you Palladium. I have separated the crystals from the HCL by dilluting it, and letting the crystals settle to the bottom, because the HCL looked clear without a yellowish color, I asumed something went wrong. So I have to start over again using fresh acid, or could I still use the 35% HCL that now looks clear ?

Then I will bring the HCL to a simmer, add the crystals and keep the process on longer with a reflux condesor.

HCL by itself has a yellowish color, will the yellowish color disapear as it takes on the stannous chloride crystals and what color with the solution get once fully saturated with crystals ?

Indeed it was a strange move to add that much crystals to an AR solution (asuming it was AR to test for gold) because now it is contaminated not only with tin but also that black color.

I also have this soxhlet extractor, and was thinking that might also be a good way to dissolve the sncl2 crysals continuously, with a reflux condensor so I can let the process run for a longer period of time, or might this be too much work to acieve our goal ?
 
I mainly use tin fishing sinkers or a very high tin content solder to make my Stannous with. I add all the ingredients together and run hot tap water over the loosely closed container until I can see a reaction on the tin. With in minutes it usable.
 
I thougt fishing sinkers are made from lead ? Although in my fishing days it was. That is why I bought a 100gr of SnCl2 crystals thinking it was the best and moste pure vorm of tin to make stannous chloride.

No idea it was so hard to make sure the crystals are dissolved and stay in the HCL with precipitating upon cooling. If the tin crystals give me the same problem again then a abandon the crystals, melt the tin (angel) figurine, pour it into shot and try to dissolve a few of those in hot HCL.
 
Hot water can dissolve a lot more tin chloride than cold. When it cools the excess crystallizes out as cold water can't dissolve as much tin chloride. This is almost universally true, salt, sugar, ferrous sulfate, silver nitrate... and so on, all would crystallize out of a hot saturated solution when cooling.
After cooling it is still saturated.

Stannous chloride doesn't need to be saturated, far from it.

Stannous chloride is one of the easiest chemicals to make, it doesn't have to be pure, it doesn't have to be concentrated, tin is easy to find (solder, pewter, old electronics, modern fishing weights, auto body work shops...) and HCl is the most common acid and still easy to find in most towns.

It's making have been described hundreds of times on the forum, both from crystals and from tin metal.

Only two rules apply.
- Keep it protected from air. Air oxidizes it and it stops working.
- If kept in a bottle with acid and metallic tin it will build up pressure that might shatter a flask. If there is a dropper with a rubber bulb it will burst first and spray the tin chloride and acid all around. If you have metal and acid in a flask or a beaker, just wrap it with some plastic kitchen foil (Saran wrap), it will break before any dangerous pressure builds up.

Göran
 
- If kept in a bottle with acid and metallic tin it will build up pressure that might shatter a flask.

I have never seen this happen but I use a minimal amount of HCl when making the test solution and all of the clients I have taught to make it have been given this simple formula. It is amazing to me that if there is one thing here on the forum that is expressed more than any other point it is about the cost of chemicals and their over-use. (and associated problems with over-use of chemicals) While at the same time Hydrochloric acid is applied in glugs rather than milliliters! I suppose metallic tin in a sealed vessel with acid could pressurize and rupture and it pays to be aware. But it pays bigger dividends to mix it right in the first place and avoid the cleanup!



Stannous chloride test solution

2 grams stannous chloride crystals.

1 gram of tin metal.

40 ml of water

5 ml Hydrochloric Acid

The tin metal and stannous chloride can be bought from Action Mining. http://www.actionmining.com
 
I will start a thread about making stannous chloride and we can all post our preferred methods. Then I can clean it up and put it in the library.

People have different reasons for different preferred methods. Some can just order what is needed and do it textbook style, and some need to go to their tackle box and make a "good enough" substitute. So maybe a few posts about each will put all of the options in 1 place.
 
The over pressure can rupture a rubber bulb on a dropper flask. Maybe not a whole bottle, but you never know. My dad blew up a bottle when he tried to make wine on blue berries when I was a kid, so you can blow up a flask from internal pressure.
Some people advice storing stannous with some metallic tin, other that it should have HCl... combine those advice and you have something going poof.

It's happened at least twice with blown rubber bulbs and the glass dropper as a siphon to get all the stannous out of the bottle in a fine mist.
I wrote about my mishap here http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=26503&p=281296#p281296
but I can't find the other guy doing the same mistake. I think it was someone that sprayed the fume hood, including an open beaker with gold chloride.

My mistake was making the stannous in the dropper bottle and not letting the reaction finish. Actually I think I just put the dropper on lightly but I must have tightened it enough to seal.

Göran
 
anachronism said:
How about a stickied post with all the Stannous details on it Goran?
I already started one... :wink:

http://goldrefiningwiki.com/mediawiki/index.php/Stannous_chloride

Just haven't finished it up. Feel free to add in or copy it anyone that wants. There are a couple of good links in it.

But you're right, I should write one article about making stannous too.

Göran
 
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