Speed up stannous with a drop HNO3?

[lanfear]

Hi guys.

I processed 20 mixed ceramic cpus in AR and only got 3 g. I knew I did not take my time with nitric additions and evaporation. So now 2 months later I am testing for additional gold in the solution.
The stannous test from the gold test solution first turned orange, and then 20 min later purple. So I am at the moment freshing up the stannous with more tin. But it is taking forever even with moderate heat on.
So I was wondering if anyone has experience with putting a drop of nitric in to speed it up? As long as the drop is used up I dont see the harm, but I am no expert..

 

[Anonymous]

3g from 20 ceramics is pretty reasonable for SOME ceramics. What yield were you expecting and what were you basing your projections on please?

 

[Anonymous]

Also you don't need to have all the tin dissolved for the stannous to be fine. If you introduce Nitric into the solution you'll make a gooey mess. Stick to the chemistry, it's HCl and tin that makes Stannous Chloride. Nitric acid makes that horrid sticky mess that I forget the name of (is it metastannic acid?, feel free to correct me chaps.)

 

[lanfear]

Yes, its metastannic acid. But that should only be a problem with a nitric solution. This is not a nitric solution. It is 30 ml of HCl with a drop of nitric.
I know 3g could be a right for some cpu. I am now looking at my notes, and it was actually 28 ceramics. So you can understand my misgivings.

 

[bswartzwelder]

Testing your unknown with Stannous Chloride is only half of the test you need to perform. Actually, it's the second half of the test.

You cannot have any idea if the stannous test is valid unless you test the stannous first. Stannous (usually) goes bad over a period of time, so if it looks like there may not be any gold present, it could just be that your stannous has gone bad. Before you test anything with stannous, you should test your stannous first with a known (good) gold chloride test solution. I purchased a standard 1% gold chloride solution online and never use stannous until after I have tested it to make sure it is in a good condition. Buy or make a gold chloride test solution and you will never have this question again. Anytime I go outside to work with my PM's, I always take two bottles out with me gold chloride and stannous chloride. Without knowing if you stannous will work correctly, you are just shooting in the dark.

 

[Anonymous]

Actually Lanfear I can't understand your misgivings Sir. There are quite a lot of ceramics with a yield of less that 0.1g out there, which would actually give 2.8g on your sample. If you could tell me what ceramics you processed then it would be clearer as to whether or not there was more gold to be dropped. You may have processed ceramics with high yields, at which point I could understand your misgivings completely but until we've got the facts, it's a bit of a moot point.

Also if I may be so bold, when you introduce Nitric to the HCL, it then has Nitric in the solution at that point. Why would you want to dissolve the Tin with Nitric when it's the reaction with HCl that produces your stannous chloride?

 

[lanfear]

Before you test anything with stannous, you should test your stannous first with a known (good) gold chloride test solution. .

The stannous test from the gold test solution first turned orange, and then 20 min later purple

I am sorry if this point was a bit vague but I have only used the stannous on my gold test solution this far.

Actually Lanfear I can't understand your misgivings Sir. There are quite a lot of ceramics with a yield of less that 0.1g out there, which would actually give 2.8g on your sample. If you could tell me what ceramics you processed then it would be clearer as to whether or not there was more gold to be dropped. You may have processed ceramics with high yields, at which point I could understand your misgivings completely but until we've got the facts, it's a bit of a moot point.

It does not matter if the yield is correct or not. I suspect it is not and are going to test my solutions accordingly. And therefor I wonder if I can make stannous faster with a drop of nitric. Thats it..

Also if I may be so bold, when you introduce Nitric to the HCL, it then has Nitric in the solution at that point. Why would you want to dissolve the Tin with Nitric when it's the reaction with HCl that produces your stannous chloride?

I dont want to dissolve it with nitric. I want to dissolve it in HCl with nitric as an oxydizer, and I am asking if anyone has done this before.





Edit: quote error

 

[GoldMaker2]

Also you don't need to have all the tin dissolved for the stannous to be fine. If you introduce Nitric into the solution you'll make a gooey mess. Stick to the chemistry, it's HCl and tin that makes Stannous Chloride. Nitric acid makes that horrid sticky mess that I forget the name of (is it metastannic acid?, feel free to correct me chaps.)

yur right use HCI NOT NITRIC

orange and purp is good,

orange is paltumin and purp is gold
on test. If I'm right

 

[MarcoP]

I dont want to dissolve it with nitric. I want to dissolve it in HCl with nitric as an oxydizer, and I am asking if anyone has done this before.

I don't think anyone has ever tried simply because you would make metastannic acid, not sure about peroxide.

 

[solar_plasma]

As you want to oxidize:

Sn⁰ -> Sn⁺²

and not further:

Sn⁺² -> Sn⁺⁴

like it can happen with HNO₃ or Cl₂,

you do not want to add an extra strong oxidizer.

Even O₂ will slowly oxidize the SnCl₂ to SnCl₄ and Sn(OH)Cl (last one has only oxidation state +2, though).

Therfore, we use a piece of tin metal and an excess of HCl in order to keep the equilibrium to the reduced side. Further are small amounts of those oxidation products soluble in an excess of HCl. We can try to keep SnCl2 solution away from air, cool and dark to slow down the oxidation by oxygen BUT:

Not air tight, since evolving H₂ might give an over pressure!

(Short explanation based on the German and the English wikipedia texts about SnCl₂ - if I should find any mistakes, next time I look into my Wiberg, I will correct 'em.)

 

[jason_recliner]

Therfore, we use a piece of tin metal and an excess of HCl in order to keep the equilibrium to the reduced side. Further are small amounts of those oxidation products soluble in an excess of HCl.

I read this is more HCl than is required to dissolve the tin. I've been instead keeping an excess of tin in my HCl - to ensure that the solution is as strong with tin as possible. Is this the wrong way around, for the purpose of maximum usable lifespan?

 

[Anonymous]

Actually Lanfear I can't understand your misgivings Sir. There are quite a lot of ceramics with a yield of less that 0.1g out there, which would actually give 2.8g on your sample. If you could tell me what ceramics you processed then it would be clearer as to whether or not there was more gold to be dropped. You may have processed ceramics with high yields, at which point I could understand your misgivings completely but until we've got the facts, it's a bit of a moot point.

It does not matter if the yield is correct or not. I suspect it is not and are going to test my solutions accordingly. And therefor I wonder if I can make stannous faster with a drop of nitric. Thats it..

Ok, you won't say what you were processing, and I've answered the chemistry question so crack on and enjoy. (I can suspect all day that I'm not earning enough but it won't change anything unless I know the figures behind my theory.)

 

[solar_plasma]

@jason

When you are making fresh SnCl2, you will still have an excess HCl. Then you add an extra piece of tin. Since there is only a little HCl left and the solution is cold, any further reaction will be slow.

I tried only to explain, what happens chemically, when making stannous, when storing and why not to use strong oxidizers.

I think you're fine with just adding a piece of tin.

 

[MarcoP]

Not air tight, since evolving H₂ might give an over pressure!

I'm luckily using a 30ml drop bottle, push air out of the pipette and close tightly. At the beginning the idea was to create little vacuum but after few days I've noticed the vacuum was slightly lost. In first place I thought the bottle didn't hold tight but in a second moment I thought gases may be produced, searched a little and find out was hydrogen gas. Now its my habit to push air out of the pipette. Thought I'd share this 2 cents idea.

 

[Barren Realms 007]

I'm luckily using a 30ml drop bottle, push air out of the pipette and close tightly. At the beginning the idea was to create little vacuum but after few days I've noticed the vacuum was slightly lost. In first place I thought the bottle didn't hold tight but in a second moment I thought gases may be produced, searched a little and find out was hydrogen gas. Now its my habit to push air out of the pipette. Thought I'd share this 2 cents idea.

That is not necessary.