Cobalt, with its chemical name, Co, lies with the transition metals on the periodic table. The atomic number of Cobalt is 27 with an atomic mass of 58.933195. Cobalt was first discovered in 1735 by George Brandt in Stockholm Sweden. It is used in many places today, such as, magnets materials, paint pigments, glasses, and even cancer therapy. The word cobalt is from the German word Kobold, which means "goblin" or "evil spirit" this term was used by miners that was really difficult to mine and harmful to the miners health.
Cobalt is a sturdy, gray metal which resembles iron and nickel. Although cobalt is ductile it is also somewhat malleable. Ductile means the metals ability to be drawn into thin wires. Malleable means is the ability of being hammered into thin sheets. Next to nickel and iron, cobalt is one of the three naturally occurring magnetic metals. When cobalt is combined with another metal to make an alloy its magnetic properties are even more apparent than the individual metal of cobalt. Cobalt's melting point is 1495 degrees C with a boiling point of 2870 degrees C. The density is 8.9 grams per cubic centimeter.
Table 1: Properties of Cobalt
|Melting Point||1495 degrees C|
|Boiling Point||2870 degrees C|
|Specific heat||0.568 J/mol K|
|Electron Configuration||[Ar] 4s2 3d7|
|Common Ions||2 (most common), 3|
|Heat of Fusion||16.06 kJ/mol|
|Heat of Vaporization||377 kJ/mol|
Cobalt has one naturally occurring isotope which is cobalt 59. Isotopes are two or more forms a element. Isotopes are different because of their mass number. The number written on the right of an element i.e 59 is the mass number. The mass number is the number of protons and neutrons contained in the nucleus of the atom.The number of neutrons in a atom is how elements vary, this variation is called an isotope. There are also 10 radioactive isotopes of cobalt that are currently known. A radioactive isotope which splits apart and emits radiation. Cobalt-60 is one of the most commonly used radioactive isotopes and is used in medicine to find a treat certain diseases including the Schilling test which determines if a patients body is making and using vitamin B12 effectively. Co-57,58 are also used for the same purpose. Cobalt-60 is also used to treat cancer, because the radiation it gives off kills cancer cells.
Cobalt is somewhat of a reactive element. It combines with oxygen in the air, but does not catch on fire and burn unless it is in powder form. Cobalt has the ability to react with most acids to produce hydrogen gas. However cobalt does not react with water that is at room temperature.
Cobalt's most important application is the production of super alloys. Super alloys consist of iron, cobalt, nickel, chromium, tungsten, aluminum, and titanium. Super alloys do not rust and retain their physical and chemical properties at high temperatures. Superalloys are used where metals are placed under a great deal of stress and high temperatures.Super alloys are commonly used in airplane parts such as jet engine components and gas turbines. Superalloys are used in gas turbines because is it is used to make electricity, which operates at a really high temperature. Cobalt is also used to make magnetic alloys. Cobalt magnetic alloys are used in devices that need to hold a magnetic field. An example of this is electric motors and generators. Cobalt can also be used for the production of cemented carbides. Cementation is the process where one metal is used to cover the coating of a second metal. Through the process of cementation a extremely hard, strong alloy such as those used in drilling tools is produced.
Cobalt is relatively abundant in nature at around 10 to 30 parts per million. The common ores of cobalt include: cobaltite, smaltite, chloranthite, and linnaeite. The largest suppliers of cobalt are Zambia, Canada, Russia, Australia, Zaire, and Cuba. Cobalt it not mined in the United States.
Cobalt compounds are commonly used to make colored glass, glazes, paints, rubber, inks, cosmetics, and pottery. These compounds compounds include: cobalt oxide, cobalt potassium nitrite, cobalt aluminate, and cobalt ammonium phosphate. Cobalt compounds can also be used as catalyst. A catalyst is a substance that is used to speed up or lower a chemical reaction, by increasing or decreasing its activation energy. For all the cobalt used in the United States about 25% of them are cobalt compounds.
Table 2: Common Compounds
|Cobalt dichloride dihydrate||CoCl2.2H2O|
Cobalt is a trace mineral that the human body needs in only small amounts. When trace metals are absent in a diet this leads to health problems. Animals use trace minerals to make essential enzymes which function as catalysts. These enzymes speed up changes that occur in the human body. Enzymes are needed for living cells to function properly For example cobalt is needed for the natural production of B-12 vitamins. B-12 vitamins ensure that enough red blood cells are produced in the human body. Cobalt also affects other animals because of its lack of presence in the soil. For example sheep in Australia become infected with a disease called Coast disease, caused by cobalt deficiency. Excess cobalt can also lead to health problems. People who work around cobalt can inhale its dust which causes vomiting, diarrhea, or breathing problems. If cobalt is presence on the skin in can lead to an irritation and rash.
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