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Chromium
by Michelle Padilla
Physical Geology
Fall 2014
  
 
 

Chromium (Cr)
 

 

        The element chromium, atomic number 24, is a hard metal with a shiny surface. The metallic luster of this material makes it appealing to the eye, one of the reasons it is often used as a steal coating.  Chromium, also known as chrome, is a solid material at room temperature.
 


 

Chromium is found in the form of ores. In order to separate the metal, the chromite ore (FeCr2O4) is oxidized to chromium oxide (Cr2O3), the metal is then separated by heating the oxide with aluminum or silicon. Though it is rare, native chromium can be found in kimberlite pipe. As the 21st most abundant element, it is present at about 100ppm concentration. It has a melting point of 3464.6°F and a boiling point of 4839.8°F, which makes it a good material for working around extremely high temperatures.
 

History
 

        Louis-Nicholas Vanquelin was the first person in Western civilization to discover chromium as an element in 1797. During Vanquelins experimentations with chromium he made many discoveries. He found that it could change to a multitude of colors in different solutions; because of this he named the element after the Greek word for color, chroma. The beautiful green color in emeralds is due to traces of chromium.
 


 

      A few years later a chemist by the name of Tassaert discovered chromium in chromite ore, now known as chromite, which is now a major source of chromium. Though Vanquelins discoveries were the first of his time, over 2,000 years ago the ancient Chinese used chromium to coat their weapons, in order to strengthen them and protecting them from tarnishing.
 

Location
 

        Chromium is rarely found by itself, it is usually found in chromite ore. Chromite is found in places such as Albania, Finland, Iran, Madagascar, New Zealand, the Philippines, Russia, Turkey and even Zimbabwe. Chromite can be found in stratiform deposits (layerd), podiform (pillow-like) deposits and beach sand. Because Chromium is not mined in the United States, more than half of the chromium used comes from recycled metal.
 

Uses of Chromium
 

As a very corrosion resistant substance, it is used a lot in industrial factories. Chromium can be used to harden steal, this is useful in the equipment used in factories and even in the auto mobile industry for car parts such as bumpers.

     However, the first form of chromium plating was used in jewelry. The use of chromium became very popular in the 1950s because the metallic look was “trendy” The word chrome soon became an everyday household word in the United States. Prior to the 1950s not many people knew about chromium or what it was.
 

Because of the high melting and boiling points, it can be used work in extreme temperatures such as welding. Chromium has the ability to maintain its shape without warping in extreme heat, this is why this element can be used the lining of jet engines.  Another place chromium is sometimes used is in the barrel of guns, as it is necessary for the lining to be able to withstand the incredible heat set off by the bullets.
 

Chromium is known for producing beautiful colors, which is why it is used as an industrial catalysts to add pigments of green, red, orange and even yellow. As early as the 1820s the most common use for chromium was in the textile industry. The color was able to bind will with fibers and as a result it prevented the dye from bleeding. One of the most common uses for this material is in leather, approximately 90% of all leather in tanned using chrome.
 

Harmful Effects
 

        Chromium, though a very useful material, can also be extremely harmful. Though only trace amounts of chromium actually enter the human cells, more recently it has been discovered that a large amount of factory workers who were exposed to hexavalent chromium also showed cases of lung cancer, damage to the nose, throat and lungs, and damage to eyes and skin. Most of these employees likely inhaled hexavalent chromium in the form of dust. These employees could have been exposed to the dangerous fumes while welding, tanning leather of producing chromium pigments. There are some forms of chromium that are more harmful than others; one of those is Chromium (VI) which is carcinogenic and toxic to humans. Many of these industries are now looking into alternatives to using chromium.

       

Work Cited

·        http://www.rsc.org/periodic-table/element/24/chromium

·        https://www.osha.gov/OshDoc/data_General_Facts/hexavalent_chromium.pdf

·        http://www.chemicool.com/elements/chromium.html

·        http://www.dartmouth.edu/~toxmetal/toxic-metals/more-metals/chromium-history.html

·        https://www.osha.gov/SLTC/hexavalentchromium/

·        http://chemistry.about.com/od/chromium/a/10-Chromium-Facts.htm

·        http://www.livescience.com/29194-chromium.html

·        http://geology.com/minerals/chromite.shtml