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Author: Subject: silver
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[*] posted on 29-11-2008 at 10:07


I wonder if the black powder is tungsten.
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Jor
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[*] posted on 2-12-2008 at 08:07


Yes I also think it is tungsten. After I decanted the dark blue solution, I saw a piece of metal in the black powder. So that is why I only used such a small amount of acid. I recall there were a lot of crystals in the solution before I diluted it. Those probably covered the surface of the metal, making it impossible for the nitric to react with the metal.

I continued dissolving it, by adding nitric and heating. The solution I already had, wich probably contained most of the silver, was being processed, by first adding sodium chloride solution until precitipte stopped to form. This took about 9g, so there really is not much metal left as I would need about 11g NaCl in theory if all metal would have dissolved.
I heated the solution to make the AgCl coarser, making it easier to decat. Next I decanted most motherliquid and washed 3 times with distilled water, and next, washed the snow-white precitipate with 2x 60-70mL of hot (70-80C) water. To both these washings were added a crystal of KI, and in the first washing there was quite a lot of lead, in the second not much. On cooling the second, there was a beautiful crytal formation, it looked like the classic golden rain.

When they both cooled to 10C (the temperature in my lab), I decated the liquid, and flushed away (contained hardly any lead), and the precitipates in both were collected as heavy metal waste.

This is as far as I am right now. Next I am going to heat the AgCl in NaOH-solution (less than 1.eq right, for every eq. of AgCl?), and add sugar. I have 2 sugars: Normal sugar, the stuff you eat, wich is saccharose, and pure lab-grade glucose. Wich one is best?

I must say, in dissolving 25g of metal, a LOT of NO2 is formed. Without a hood, this is quite hazardous. As I live in a neighbourhood, I scrub the gas through NaOH. The final dissolving part, wich i am doing right now, I am doing that without a srubber, but I do it in steps, so add a ml or 2 of conc. nitric, dissolve and wait for 10 mins, there is no smell of NO2 in the gardens. I walk outside now and then, and no NO2 is obvserved.

[Edited on 2-12-2008 by Jor]

[Edited on 2-12-2008 by Jor]
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