Heating in oxygen produces Co 3O 4 which loses oxygen at 900 ☌ (1,650 ☏) to give the monoxide CoO. Ĭobalt is a weakly reducing metal that is protected from oxidation by a passivating oxide film. The ideal transition temperature between the hcp and fcc structures is 450 ☌ (842 ☏), but in practice the energy difference between them is so small that random intergrowth of the two is common. Metallic cobalt occurs as two crystallographic structures: hcp and fcc. Cobalt has a relative permeability two-thirds that of iron. The Curie temperature is 1,115 ☌ (2,039 ☏) and the magnetic moment is 1.6–1.7 Bohr magnetons per atom. Cobalt in inorganic form is also a micronutrient for bacteria, algae, and fungi.Ĭharacteristics A block of electrolytically refined cobalt (99.9% purity) cut from a large plateĬobalt is a ferromagnetic metal with a specific gravity of 8.9. Vitamin B 12, the best-known example of the type, is an essential vitamin for all animals. Cobalt-60 is a commercially important radioisotope, used as a radioactive tracer and for the production of high-energy gamma rays.Ĭobalt is the active center of a group of coenzymes called cobalamins. Cobalt occurs naturally as only one stable isotope, cobalt-59. The compounds cobalt silicate and cobalt(II) aluminate (CoAl 2O 4, cobalt blue) give a distinctive deep blue color to glass, ceramics, inks, paints and varnishes. Ĭobalt is primarily used in lithium-ion batteries, and in the manufacture of magnetic, wear-resistant and high-strength alloys. World production in 2016 was 116,000 tonnes (114,000 long tons 128,000 short tons) (according to Natural Resources Canada), and the DRC alone accounted for more than 50%. The Copperbelt in the Democratic Republic of the Congo (DRC) and Zambia yields most of the global cobalt production. The element is, however, more usually produced as a by-product of copper and nickel mining. Today, some cobalt is produced specifically from one of a number of metallic-lustered ores, such as cobaltite (CoAsS). In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the kobold. Miners had long used the name kobold ore ( German for goblin ore) for some of the blue pigment-producing minerals they were so named because they were poor in known metals and gave off poisonous arsenic-containing fumes when smelted. The free element, produced by reductive smelting, is a hard, lustrous, silver metal.Ĭobalt-based blue pigments ( cobalt blue) have been used since ancient times for jewelry and paints, and to impart a distinctive blue tint to glass, but the color was for a long time thought to be due to the known metal bismuth. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The filter paper can be cut into small strips and stored in a desiccator with dry silica gel.Cobalt is a chemical element with the symbol Co and atomic number 27.Soak filter paper in this solution, drain and dry in an oven (set at no more that 100 ☌), so that it is a definite blue colour.Dissolve 5 g of hydrated cobalt(II) chloride in 100 cm 3 of water (solution is TOXIC).The indicator papers should be handled as little as possible and hands washed after use. Cobalt chloride (TOXIC, DANGEROUS FOR THE ENVIRONMENT, may cause SENSITISATION) – see CLEAPSS Hazcard HC025 and CLEAPSS Recipe Book RB030.Read our standard health and safety guidance.Hexahydrate cobalt(II) chloride CoCl 2♶H 2O (TOXIC, DANGEROUS FOR THE ENVIRONMENT, SENSITISER ), 5 g.The hexahydrate is deep purple in color, whereas the anhydrous form is pale blue. Cobalt chloride paper is useful because the hydration/dehydration reaction occurs readily making the paper an indicator for water. It is usually supplied as the hexahydrate CoCl 2♶H 2O. You can use the papers to test for the presence of water, where the colour changes from blue to pink.Ĭobalt(II) chloride is an inorganic compound of cobalt and chlorine, with the formula CoCl 2. This resource provides instructions for preparing your own cobalt chloride indicator papers. RSC Yusuf Hamied Inspirational Science Programme.Introductory maths for higher education.The physics of restoration and conservation.
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