It is no secret that mercury compounds are very toxic and toxic. In the United States, they are banned for use in most cosmetic products, and in Canada are included in the list of the most dangerous substances. However, they are widely used in the chemical industry for the manufacture of paints, fungicides, plastic, as well as in medicine and technology. One of the representatives of this class of substances is mercury (II) chloride, which is better known by its second name - mercuric chloride. Let's look at this connection in more detail.
Formula and Properties
2-valent mercury chloride is designated HgCl 2 . This compound is a white crystalline powder. At a temperature of 277 ° C it begins to melt, and at 304 ° C it boils. Under normal conditions (25 ° C), its density is 5.43 g / cm 3 . Mercury chloride is sublime easily, it is notable for its volatility. The solubility of mercuric chloride in water largely depends on its temperature. So, at 20 ° C this indicator is only 6.6%, but it is worth bringing the water to a boil (100 ° C) and it reaches 58.3%. In addition, mercury chloride can dissolve in ether, acids, pyridine; in a NaCl solution, this process is accompanied by the formation of complex compounds. As an electrolyte, HgCl 2 is rather weak. In daylight, especially when in contact with organic compounds, this substance is easily reduced to monovalent chloride Hg 2 Cl 2 (calomel) and metallic mercury.
Getting
In large quantities, mercury (II) chloride is currently produced only through direct synthesis from mercury and chlorine. The second method of producing mercuric chloride consists in dissolving HgO in concentrated hydrochloric acid (HCl). In practice, it is used less often, mainly during laboratory experiments. In the first case, mercury is heated in a chlorine atmosphere to a very high temperature (about 340 ° C), after which it will ignite and burn with the formation of a bluish-white flame. The resulting vapor thickens as it cools and, depending on the production technology, form a fine powder or solid pieces.
Application
It is worth noting that mercury chloride was the first Hg-based substance to be used as an antiseptic and disinfectant. In this regard, mercuric chloride is highly effective, but at the same time it is very toxic. It is able to be absorbed through the skin and mucous membranes and accumulate in the human body. Previously, when people did not yet know the dangers of mercury chloride, it was used to cure skin diseases. Now in medicine it is used more to disinfect clothes, underwear, patient care items, etc. Since this substance is very toxic, its solutions are often specially stained so that, inadvertently, it is not confused with other medicines.
In industry, mercury chloride is used in electroplating, for preserving wood, in thermal metallization and bronzing. Sublimate is used for the manufacture of batteries, paints for the underwater hulls of ships. It is used for tanning leather, in lithography, photography, as an insecticide, etc.