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Bismuth
by Joshua Pinkerton
Physical Geology
Spring 2014
  
 
                                                               Bismuth
 

     Discovered by the German scientist Claude François Geoffrey (1753), bismuth is a lesser known metal that is brittle and rather different than many other metals. This mineral is a pale silver metal that can have a pinkish hue as well as a relatively low melting point.  It is used for several purposes in commercial, industrial as well as cosmetic fields.  Its low hardness and melting point make it extremely useful for alloys and is replacing other metals due to its ease of adaptation.  Its abbreviation is Bi, its atomic number is 83 and its atomic weight is 208.98037.


     Bismuth is a little different than most metals in several ways: First of all it has a very high electric resistance and is only second to mercury in being the worst thermal conductor.   Bismuth does not break down from oxygen, but can dissolve in water and nitrogen atmospheres, and bismuth salts are not water soluble. This makes for a rather strange, but useful metal. It is also very brittle in its pure form, causing it to break easily and necessitating its combination with other metals in the form of alloys to make it more useful.  Recently, Bismuth has been replacing lead and other metals due to its malleability and low melting temperature, as well as its low toxicity.  Making it not only the easier choice, but the more eco-friendly one.  Because of that, Bismuth is now used in bird shot and fishing weights, as well as solder.  Due to its low melting point, it is also used to make softer alloys of metals such as iron. Bismuth is also used in pigments and glazes because of its iridescence.
 

     Researchers in the medical field are also using bismuth in various experiments and processes.  In everyday life almost everyone knows about Pepto-Bismol as it has been known to help a variety of stomach and GI related issues. This among other products containing bismuth are on the shelves at our local stores even though most people don’t really know what it is made of.  Including some beauty products, like blush.  Bismuth is mainly produced as a by-product from refining tin, lead, copper, and other sources. In its raw form, it is usually crystallized within those other ores. The few places it is mined are Bolivia, Peru, Japan, Mexico and Canada, but only to the extent of 3-10000 tons per year.

     Like any other metal, it does have its health risks if over exposed or unprotected.  Inhalation of bismuth can be deadly and is considered poision.  Bismuth effects the lungs, kidneys and liver the most, being that these organs try to filter out things that are bad for our bodies, they tend to be where heavy metals and other unwanted chemicals end up.  “Acute effects: Inhalation: POISON. May be a nuisance dust causing respiratory irritation.  May cause foul breath, metallic taste and gingivitis. Ingestion: POISON.  May cause nausea, loss of appetite and weight, malaise, albuminuria, diarrhea, skin reactions, stomatitis, headache, fever, sleeplessness, depression, rheumatic pain and a black line may form on gums in the mouth due to deposition of bismuth sulphide. Skin: May cause irritation. Eyes: May cause irritation.”

Bismuth provides a less toxic, more malleable, less dense alternative to lead and other heavy metals, as well as being an easy by-product that gets the job done. Though it does not seem we will be coming to an end of the Bismuth supply any time soon, we will undoubtedly be able to substitute it with another mineral if necessary.

 

  

 

Creating your own bismuth crystals is easy and fun, and there are many educational and instructional videos on Youtube as well as other media sites.

“Grow Bismuth Crystals”

      “Bismuth has a low melting point (271°C or 520°F), so it is easy to melt over high cooking heating. You are going to grow the crystals by melting the bismuth in a metal 'dish' (which will have a higher melting point than the bismuth), separate the pure bismuth from its impurities, allow the bismuth to crystallize, and pour away the remaining liquid bismuth from the crystals before it freezes around the crystals. None of this is difficult, but it takes some practice to get the cooling time just right. Don't worry -- if your bismuth freezes you can remelt it and try again. Here are the steps in detail:

·         Place the bismuth in one of your metal 'dishes' and heat it over high heat until it melts. It's a good idea to wear gloves since you are producing a molten metal, which is not going to do you any favors if it splashes onto your skin. You'll see a skin on the surface of the bismuth, which is normal.

·         Preheat the other metal container. Carefully pour the melted bismuth into the heated clean container. You want to pour the clean bismuth out from under the gray skin, which contains impurities which would negatively affect your crystals.

·         Set the clean bismuth in its new container on a heat-insulated surface (e.g., set the container back on the burner, but turn the power off). The cooling rate of the bismuth affects the size and structure of the resulting crystals, so you can play with this factor. Generally, slower cooling produces larger crystals. You do not want to cool the bismuth until it is solid!”   (1)

·         When the bismuth has started to solidify, you want to pour the remaining liquid bismuth away from the solid crystals. This happens after about 30 seconds of cooling. You can tell it is about the right time to pour the liquid away from your crystals when the bismuth is set, but has just a little jiggle to it when jarred. Sounds scientific, right?

·         Once the crystals have cooled, you can snap them out of the metal container. If you are not satisfied with the appearance of your crystals, remelt and cool the metal until it is just right.”

 

Melting Point

271.3°C

Boiling Point

1560 °C

Density

9.8g/cm3

Thermal Conductivity @ 20°C

0.020cal/(s.cm.°C )

Specific Heat @ 20°C

0.0294cal/g

Latent Heat Of Fusion

12.5k-cal/g-atom

Brinell/Mohs Hardness

2-2.5











 

 

 

Works Cited

      (1)   Grow Bismuth Crystals,  By Anne Marie Helmenstine, Ph.D.
http://chemistry.about.com/od/crystalrecipes/a/grow-bismuth-crystals.htm
(2)
   Copyright © 1998-2014 Lenntech B.V,
http://www.lenntech.com/periodic/elements/bi.htm