aga
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Success at Turning Lead into Gold
Today i tried the Golden Rain experiment.
0.8g Lead Nitrate Pb(NO3)2 in 250ml water
1.1g Potassium Iodide KI in 250ml water
Mix both solutions in a 500ml conical flask, and goggle at the instant yellow cloud formed.
Heat to around 80 C and all of the yellow Lead Iodide PbI2 will re-dissolve, leaving a clear solution.
Take off the heat and watch intently for hours as beautiful Gold coloured lead iodide crystals shower out of solution.
Leave to stand until cool (or refrigerate) then filter. Wash the crystals in the filter paper a couple of times with cold water.
Leave the filter paper & crystals to dry.
Scrape off and stuff into a bottle labelled "Lead Iodide".
The reaction is :
Pb(NO3)2 + 2 KI => PbI2 + 2 KNO3
I used an excess of KI to ensure all the Lead Nitrate reacted, seeing as it's rather poisonous.
[Edited on 19-5-2015 by aga]
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Loptr
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Very nice, aga. Some pictures might be nice to go along with your post.
I do have to admit that I thought the PhdChemist was back when I read the title of this thread, until I saw that you were the poster... 
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DraconicAcid
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Don't use too much of an excess of potassium iodide, because you will form soluble lead complexes such as K2PbI4.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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MrHomeScientist
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I didn't know about soluble complexes like that, thanks! When I did this experiment, I also used an excess but at the end rinsed everything with a
baking soda solution. That should get rid of all the lead as the very insoluble carbonate.
And pictures are mandatory for this experiment!
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Bot0nist
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I'm sure it was a beautiful reaction, aga. I would love to try this myself, I hear it's quite a spectacle. Any chance of some photos? Did you prepare
the lead nitrate yourself? If so did you fuse elemental lead with a nitrate salt or dissolved in HNO <sub>3 </sub>, or salt metathesis
(double displacement reaction) using a different soluble lead salt?
Edit: I thought it was a PHDchemist post as well, at first glance.
[Edited on 19-5-2015 by Bot0nist]
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aga
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Fotygrafs
   
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aga
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Quote: Originally posted by MrHomeScientist  | | I didn't know about soluble complexes like that, thanks! When I did this experiment, I also used an excess but at the end rinsed everything with a
baking soda solution. That should get rid of all the lead as the very insoluble carbonate. |
Same Here, on all three points !
| Quote: Originally posted by Bot0nist | | I'm sure it was a beautiful reaction, aga. I would love to try this myself, I hear it's quite a spectacle. Any chance of some photos? Did you prepare
the lead nitrate yourself? |
It truly is beautiful to watch.
Yes, i made the Pb(NO3)2 by reacting some 1g lead weights with HNO3, wait a few days, filter, boil down and wait for crystals
(as i recall).
[Edited on 19-5-2015 by aga]
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Bot0nist
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Beautiful! Thanks aga!
U.T.F.S.E. and learn the joys of autodidacticism!
Don't judge each day only by the harvest you reap, but also by the seeds you sow.
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aga
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It is a really great experiment to do, and very very easy.
Just do as MrHomeScientist says and rinse off all the glassware, filter paper and byproducts with a warm sodium bicarbonate solution to render any
remaining lead salts as safe as possible afterwards.
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Pumukli
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Beautiful experiment although the photos can't show the real shine and glittering effect of the crystals.
Transforming the excess Pb(2+) ions into carbonate (or hydroxy-carbonates) is not the safest way to achieve a non-toxic substance though! I read
somewhere that lead phosphate is less soluble so washing up with a phosphate solution might be a better approach.
I also heard that carbonates and hydroxy-carbonates of lead can be absorbed through the skin. Maybe because the human skin have an acidic pH (sweat).
(Don't ask for a citation: I don't know where I read or heard this!) Actually I want to hear other's opinion on the matter!
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vmelkon
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| Quote: Originally posted by Pumukli | | I read somewhere that lead phosphate is less soluble so washing up with a phosphate solution might be a better approach. |
Ksp of lead compounds
PbCO3 = 1.46 x 10−13
PbS = 9.04×10−29
Pb3(PO4)2 = 8.1 x 10-47
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