April 8, 2006
Lithium metal from electrolysis of a Lithium Chloride / Potassium Choride Eutectic
From my reading adventures I found that a mixture of 45% LiCl w/ 55% KCl leads to a mixture that melts at a mere 450 °C, well within my reach. Out of curiosity I loaded 10 grams of the lithium chloride and 12 grams of potassium chloride into the crucible above and blasted it from below with a propane torch. Within a few minutes the two solids had fused and begun to melt and it wasn't long before I had a nice liquid in my crucible. I converted the crucible to the anode (you can see the clamp in the right hand edge of the photo above) and made a nickel rod the cathode.
Initally water was electrolyzed when the rod was inserted, there was vigorous bubbling but not much of anything else. The melt was VERY conductive. Finally the amps shot up even more and a glow formed around the cathode that shorted out the circuit breaker in my power supply, likely some lithium formed between the crucible and the cathode and make the breaker pop. So after it cooled for a minute it fixed itself and I tried again. If I hardly touched the cathode to the surface it lit up brightly and drew 15 amps of current. Shortly thereafter a small red fire would occur and pop or spray out.
From the book that I read on this the lithium produced in this way is 99% pure so I had great hopes but lithium is quite reactive and chlorine was being generated right along side it so none was recovered. Hopefully I will have better luck next time with a partitioned cell.
Potassium bismuthate from Bismuth hydroxide and Potassium hydroxide
According to my chemistry encyclopedia, potassium bismuthate is the product from heating bismuth trioxide with potassium hydroxide exposed to the air for some time. So I gave it a try. I made some bismuth hydroxide by dissolving bismuth in nitric acid and afterwards precipitating it with KOH. Likely some of the product was not in fact the true hydroxide but it really was a moot point because of my next step. The crude product from the previous step was placed into a steel crucible and heated over a propane torch for 15 minutes to decompose any nitrate present and dehydrate any hydroxide to give my desired bismuth trioxide.
To the crucible was then added twice as much KOH as there was bismuth trioxide. The white powder dissolved rapidly in the molten KOH to give a green solution with yellow particulate suspended in it. Yellow being the color of my desired compound I felt some degree of success had already been acheived. So I allowed the mixture to remain molten and exposed to air for twenty or thirty minutes then it was poured out onto a steel slap pictured above. The blue colored material coming from the top of the melt and the green colored material from the bottom.
A portion of this crude product was added to a test tube where it disintigrated rapidly giving brown and yellow precipites. The yellow portion was heavier then the brown and sunk to the bottom more rapidly. Bubbles were continuisly evolved as would be expected from the bismuthate decomposing but no further tests were preformed.
Organometallic lead madness!
From several sources and from personal communications I found that preforming electrolysis between lead electrodes in a solution of 30% sulfuric acid with twice as much acetone added gives a red liquid assumed to be diisopropyl lead. So, I went onward just as stated above. Problem was that I could never isolate it. The red compound clung to the cathode and stuck to the top of it and decomposed readily from the air. When I was ready to give up I had a clear solution albeit slightly tinged yellow. And after some time I found I had the solution above. The diisopropyl compound is the minor product fromed. The major product is the tetraisopropyl compound which is not colored. This likely accumulated in my acetone/sulfuric acid phase and after some time oxidized from the air or hydrolyzed and reacted with the sulfuric acid to give a precipitate of lead sulfate.
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