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February 24 2012 6 24 /02 /February /2012 19:18

1-18 - Use Control + F to find what you want in here

Bismuth reactions: The bismuth precipitate has turned pure white upon drying. Reaction with bleach seems to produce no oxidation to the tetroxide. Addition of hydrogen peroxide, however, turns it yellow. Is this yellow solid a peroxo complex of bismuth?  Below is the “tetroxide” (left), the peroxo complex (center), and the precipitate (right).

Cobalt precipitation: The magnesium has completely precipitated the cobalt from the solution of cobalt(II) chloride.

Bismuth work: I dissolved some of the bismuth precipitate in hydrochloric acid. It appears to have retained no carbonate ions, and is almost wholly bismuth(III) hydroxide. I then added sodium iodide solution to the bismuth solution. A deep yellow solution was obtained. Upon neutralization with sodium bicarbonate, a bright yellow precipitate formed which got duller yellow as the pH rose. This solution is likely a solution of bismuth triiodide in hydrochloric acid. All of this bismuth chemistry was just done with a few tiny pieces of bismuth. The largest is barely thicker than a pencil lead. These bismuth chunks were placed in sodium hypochlorite solution for half an hour. They were then removed, washed, and immersed in hydrochloric acid. No chlorine gas was produced, showing that no higher bismuth oxide was produced by the hypochlorite.

Bismuth dissolution: The remaining bismuth pieces are placed in a 2:1 mixture of 3% hydrogen peroxide and 5% acetic acid. Dissolution appears to be very slow, with a small amount of cloudiness forming. Cloudiness is most likely the result of bismuth acetate hydrolysis. Neutralization with sodium bicarbonate yields no precipitate.

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Bismuth-copper(II) chloride reaction: Bismuth is reacted with aqueous copper(II) chloride solution. A small amount of gas is evolved, and the solution becomes cloudy. The reaction then ceases. Addition of hydrochloric acid dissolved the precipitate, which is probably a mixture of copper(I) chloride and bismuth(III) oxychloride, but no further reaction with the bismuth occurs. When precipitated with sodium bicarbonate and excess ammonia, a cloudy copper(II) ammine complex is formed. This means that the bismuth(III) hydroxide is behaving like a gelatin. It might precipitate out later, but it is unlikely that it will do so without first occluding some copper compounds.

Chlorate production: Bleach is warmed to disproportionate it. Then production is stopped.

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Bismuth-copper(II) chloride reaction: A small amount of bismuth(III) hydroxide, contaminated with copper, settled out on the bottom of the copper(II) ammine solution. It was washed with ammonia. As is visible, all of the copper washes away, leaving only the white insoluble bismuth hydroxide behind.

Capacitor dissolution: The dielectric from an unknown capacitor was immersed in hydrochloric acid. No reaction occurred. Therefore, it is just an ordinary ceramic capacitor.

Chromate production: The metal oxide mixture produced by oxidizing the 18/0 stainless steel spoon is placed in sodium hypochlorite solution. A yellow coloration begins coming off the oxides, showing that some chromate is produced.

Tantalum capacitors: I obtained three tantalum capacitors. I cracked one open and it consists of an outer manganese dioxide layer with an inner core of pure tantalum. The manganese dioxide can be dissolved, leaving the clean tantalum behind. However, in the cold near-freezing outdoor environment (because of  chlorine production), the manganese dioxide dissolves extremely slowly. The tantalum core is hit with a hammer and seems shatter-proof. The wire in the center is actually made of pure tantalum. After dissolution for a while, the solution is washed down the drain. Despite the tantalum’s high density, it is taken along with the water flow and is lost.

Samarium-cobalt magnet: A cheap speaker verified to contain a samarium-cobalt magnet is ripped open and the magnet, which closely resembles a neodymium magnet, is removed. It dissolves in acetic acid similarly to a neodymium magnet as well. Supposedly the most common magnet contains a small percentage of iron (ugh) and copper as well. The iron will probably begin to dissolve in the acetic acid along with the samarium, just like in the mischmetal.

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Periodate reduction: Addition of hydrochloric acid to wet sodium periodate crystals produces a yellow solution which seems to be iodine monochloride. NaIO4 + 8 HCl -> NaCl + ICl + 3 Cl2 + 4 H2O is a possible reaction. A smell of chlorine was produced, but no fizzing was observed as the crystals were damp and the hydrochloric acid dissolves chlorine well.

Tantalum cleaning: The dirty tantalum was placed in hydrochloric acid. Some chlorine production is observed, and a dark brown manganese(III) chloride solution begins seeping off the tantalum (because it is cold). Eventually, however, this solution will decompose releasing its chlorine and turn colorless. It does so faster when warmed, even in a hand. So it is warmed by a hot water bath. When the dissolution has been going on for several hours, it is stopped. The greenish-blue iridescent color produced when tantalum is anodized to form the dielectric layer is visible through the thin film of remaining manganese dioxide. The tantalum wire protruding from the pellet is also iridescent, showing that it was anodized as well.

Lead chromate production: Lead acetate solution is produced by dissolving lead in 1:1 mixture of acetic acid/hydrogen peroxide. This solution is reacted with the sodium chromate solution. A bright yellow precipitate is formed. This is filtered and dried.

Chromium peroxide formation: Hydrochloric acid is added to the chromate solution. No visible chlorine is evolved, showing that the bleach must have been almost entirely consumed. Hydrogen peroxide was then added. A deep purple-blue solution of chromium(VI) peroxide formed, which quickly decomposed into a green chromium(III) chloride solution with the evolution of oxygen. Addition of ammonia formed no precipitate of chromium(III) hydroxide because the solution was too dilute.

Basic lead chromates: When lead chromate is added to ammonia, it turns orange, showing the formation of a basic lead chromate. Sodium hydroxide will probably make it red.

Acidic lead chromates: When hydrochloric acid is added to lead chromate, it turns white, and a yellow solution is leached off.

Dichromate formation: Acetic acid is added to sodium chromate solution in an attempt to produce a dichromate solution but a yellow precipitate of what appears to be lead chromate (eyedropper contamination?) is thrown down instead.

Chromate reduction: A non-acidified chromate solution is reacted with hydrogen peroxide. The typical chromium(VI) peroxide forms, which is decomposed into a yellow-brown solution. Addition of hydrochloric acid produces a gray-green solution of chromium(III) chloride. More chromate solution is reduced with ascorbic acid. A purple-gray solution of chromium(III) chloride is formed, which becomes less purple as it ages. The remainder of the chromate solution is reduced with ascorbic acid and flushed down a drain.

Samarium-cobalt magnet dissolution: The magnet is removed, and the solution of samarium and iron chlorides is light brown. Ammonia is added, which precipitates the all-too-familiar dark green iron(II) hydroxide. Hydrochloric acid is added, and a red-orange solution that does not appear like an iron(II) or iron(III) chloro complex is produced. Zinc is added to reduce the iron and any other non-rare earth metals. The solution lightens amid fizzing of hydrogen. Once it is light, it is neutralized with sodium bicarbonate. A very light brown precipitate is formed which does not oxidize. Because of the presence of the zinc, any trivalent iron would be reduced to divalent iron, and a color change would be visible upon exposure of the hydroxide to air. However, there was none, and so the residue must be iron-free samarium carbonate. However, the precipitate appears to have darkened, but not turned browner.

End of experiments: This is probably the end of experiments for my winter break.

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