Density of mercury in nature and in life

The first mention of mercury, which has survived to this day, dates back to approximately V century BC. In those days, it was mined by the only known way at that time - burning cinnabar (a mix with sulfur) along with coal. When heated, the cinnabar decays into mercury and sulfur that make up it, the latter combines with oxygen and forms a volatile compound. At room temperature, the density of mercury (kg / m3) is 13,545.7 kilograms per cubic meter, while it is the only metal that we normally observe in the liquid state.

In nature, the relative density of mercury is low and is estimated to be about 0.03-0.09 mg per kilogram of rock. Concentrated deposits are fairly rare, mostly mercury compounds are literally dispersed throughout the near-surface layer of the earth's crust. The world knows about 5,000 deposits of this metal, of which only about 500 have been developed. According to modern science, a much higher density of mercury (relative to other components) is observed in the earth's mantle, from where it enters the surface and into the atmosphere during volcanic eruptions, Earthquakes, tectonic faults, etc. The so-called mercury breath of the planet evaporates from the depths of about 3,000 tons of mercury per year; Humanity (according to scientists' estimates) adds to it about 4,000 tons more annually. On a planetary scale, the magnitude may seem small, but one should take into account the extremely low solubility of most mercury compounds, because of which they are practically not eliminated from the body.

The ability of heavy metals to gradually accumulate is a very unpleasant feature, especially when one considers that they accumulate not only in the human body, but also in the tissues of animals serving our food. The relative density of mercury accumulated in the animal body is not the same for different species; In addition, the influence is exerted by habitat and age. For example, predator fish gradually accumulate in their tissues compounds containing mercury; The density of these compounds grows faster in life with predators than in fish that feed on plant foods. This factor must be taken into account, especially if the reservoir from which the fish is caught is exposed to sewage. Similar conclusions are also valid for terrestrial animal species and for birds.

Despite the high toxicity of mercury, the refusal to use it is hardly possible. Probably, its use in medical thermometers is most well known (good combination: medicine and candid poison). The use of mercury in the measurement of temperature is dictated by an unusually advantageous combination of its qualities: 1) a large range of measured temperatures; 2) more extensible than other liquids (which allows to increase the accuracy of the measurement); 3) complete absence of wetting of the glass by mercury; 4) low heat capacity, which ensures a quick reaction of the thermometer to changes in external conditions.

No less common are fluorescent lamps, in which radiation is formed by mercury vapor under the action of a glow discharge. Usually the density of mercury (more precisely, its vapor) in the lamp bulb is small, the main pressure is formed by an inert gas. Visible light appears due to the phosphor deposited on the glass surface: ultraviolet radiation of mercury vapor is completely absorbed, and energy is redistributed in the visible range. The quality of light (chromaticity, continuity of the spectrum) depends on the specific composition of the phosphor. For residential premises, it is recommended to choose a lamp with a warm light (or a combination of warm and daylight lamps in a set), for office, the day is optimal, i.e. Slightly cooler lighting.