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currawong
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Lead iodide
I'm sure this has been posted many times before, but this was my first time seeing the 'golden rain' demonstration which has been on my bucket list
for a long time. First time I did it I used 0.1 molar solutions of each which was clearly too concentrated to see it properly (turned solid yellow
instantly) but it worked much better when I used very dilute KI. Thanks to j_sum1 for the lead nitrate.
 
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j_sum1
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Mood: Just got through yet another "take this job and shove it" moment.
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Yes. Keep concentration relatively low. Then, after the reaction, heat the solution until all the precipitate dissolves. For large floaty crystals,
allow it to cool slowly.
Glad you found some goodies in that package. I has forgotten that I had some Pr6O11 and spent some time last weekend making some PrCl3, Pr2(SO4)3 and
Pr(NO3)3. I may make some bromide and aspirinate because -- well, I can.
Edit
I should add, unless you like dealing with soluble lead waste, it is better to have the KI in excess. It is still good practice to filter and then
treat the filtrate with carbonate to precipitate as much lead as possible to be disposed of as a solid or reclaimed.
[Edited on 27-11-2025 by j_sum1]
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currawong
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It did occur to me after I did it that it would have been better to use an excess of iodide. I already have a container for heavy metal waste that I
treat with sodium carbonate though which I can put the waste solutions in. As an aside, this is actually a syllabus mandated practical but my school
ignored it because the head teacher decided watching a youtube video was the same thing as doing a prac. It's really sad, the old textbooks have so
many interesting demonstrations but now you get the impression the point of doing chemistry is purely to rank students and determine who will get into
medicine at uni.
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Thyzoid
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Finally no more need to make my own cyanide! I can just buy it now :3
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Radiums Lab
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That's a boatload of cyanide. You will never need any more of it.
Water is dangerous if you don't know how to handle it, elemental fluorine (F₂) on the other hand is pretty tame if you know what you are doing.
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Thyzoid
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Trust me. This bottle won´t even last two years. In the past two months i used up about 500g of the old cyanide in two preparations
[Edited on 30-11-2025 by Thyzoid]
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bnull
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Ammonium copper sulfate crystal, approx. 4 mm long. I didn't expect it would grow so well formed.
  
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Texium
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Beautiful! Think you'll keep it, or try using it as a seed for a larger crystal?
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bnull
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I'll keep it. It is perfect and grew unexpectedly in a test tube. I have more than enough seeds in another test tube just waiting to be collected and
used.
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