|
Minerals in Detail
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
COBALT
Cobalt - chemical details
| Symbol | Co |
| Atomic number | 27 |
| Atomic mass | 58.9332 g.mol-1 |
| Electronegativity | 1.8 (according to Pauling) |
| Density | 8.9 g.cm-3 at 20°C |
| Melting point | 1495 °C |
| Boiling point | 2927 °C |
| Vanderwaals radius | 0.125 nm |
| Ionic radius | 0.078 nm (+2) |
| 0.063 nm (+3) |
| Isotopes | 8 |
| Electronic shell | [ Ar ] 3d7 4s2 |
| Energy of first ionisation | 757 kJ.mol-1 |
| Energy of second ionisation | 1666.3 kJ.mol-1 |
| Energy of third ionisation | 3226 kJ.mol-1 |
| Standard potential | - 0.28 V ( Co2+/ Co ) |
| +1.84 V ( Co3+/ Co2+ ) |
| Discovered | 1737 - George Brandt |
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
Cobalt - Description
Cobalt is a ferromagnetic, silver-white, hard, lustrous, brittle element. It is a member of group VIII of the periodic table. Like iron, it can be
magnetized. It is similar to iron and nickel in its physical properties. The element is active chemically, forming many compounds. Cobalt is stable in air
and unaffected by water, but is slowly attacked by dilute acids.
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
Cobalt - Industrial applications
Cobalt is used in many alloys, magnets and magnetic recording media, as catalysts, as drying agents for paints and inks. The radioactive isotopes, is used
in medical treatment and also to irradiate food, in order to preserve the food and protect the consumer. For details on industrial applications and impact
on the environment see www.lenntech.com/Periodic-chart-elements/Co-en.htm
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
Cobalt - In natural form
Most of the Earth's cobalt is in its core. Cobalt is of relatively low abundance in the Earth's crust and in natural waters, from which it is precipitated.
Although the average level of cobalt in soils is 8 ppm, there are soils with as little as 0.1 ppm and others with as much as 70 ppm.
In the marine environment cobalt is needed by blue-green algae (cyanobacteria) and other nitrogen fixing organisms. Cobalt is not found as a free metal and
is generally found in the form of ores. Cobalt is usually not mined alone, and tends to be produced as a by-product of nickel and copper mining activities.
The world's major producers of cobalt are the Congo, mainland China, Zambia, Russia and Australia. It is also found in Finland, Azerbaijan, and Kazakhstan.
World production is 17.000 tonnes per year.
Chemical Details | Description | Industrial Applications | In Nature | Health Impacts
Cobalt - Impact on health
As cobalt is widely dispersed in the environment humans may be exposed to it by breathing air, drinking water and eating food that contains cobalt. Skin
contact with soil or water that contains cobalt may also enhance exposure. Cobalt is not often freely available in the environment, but when cobalt
particles are not bound to soil or sediment particles the uptake by plants and animals is higher and accumulation in plants and animals may occur.
Cobalt is beneficial for humans because it is a part of vitamin B12, which is essential for human health. Cobalt is used to treat anaemia with pregnant
women, because it stimulates the production of red blood cells. The total daily intake of cobalt is variable and may be as much as 1 mg, but almost all will
pass through the body unadsorbed, except that in vitamine B12.
However, too high concentrations of cobalt may damage human health. When we breathe in too high concentrations of cobalt through air we experience lung
effects, such as asthma and pneumonia. This mainly occurs with people that work with cobalt.
|
