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March 23 2012 6 23 /03 /March /2012 12:41

I was looking for a solvent for bismuth metal, which I purchased from a gift shop for the Franklin Mineral Museum. I knew that acetic acid would only form the insoluble subacetate, so it cannot be used. I do not have nitric acid or sulfuric acid, so hydrochloric acid remains. Addition of hydrogen peroxide to the hydrochloric acid allowed the bismuth to be oxidized and the oxide to be dissolved, leaving a solution of bismuth(III) chloride. This solution is dense and colorless, visible as swirls when the dissolving solution is disturbed. The remaining bismuth is pitted and generally corroded.

 

Bismuth-and-chloride.JPG

A large amount of ascorbic acid crystals are added and some tincture of iodine is added as well. The tincture of iodine is decolorized, but no bismuth iodide is produced. I cannot seem to obtain bismuth iodide.

 

I then added water to the solution, to the top of the vial. The bismuth instantly hydrolyzed in the diluted solution, producing a white precipitate of BiOCl.

 

Bismuth-chloride-hydrolysis.JPG

When this precipitate is further neutralized with sodium bicarbonate, it turns light yellow as bismuth hydroxide is produced.

 

After disposal of the relatively nontoxic bismuth precipitate down the sink (bismuth solutions are too acidic to stay as ions in aquifers, so they precipitate and remove themselves naturally), I repeated the experiment. I took some of this bismuth solution and reacted it with an iodide. A yellow iodo complex is obtained.

 

Bismuth-iodo-complex.JPG

When this is diluted with water, it turns white again as the iodide hydrolyzes.

 

I then took some more of the bismuth solution and placed it on a piece of zinc. The zinc turned black as the bismuth chloride was reduced to elemental bismuth. The resulting layer was quite thick.

 

Bismuth-chloride-zinc-reaction--4-.JPG

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