It's no secret that mercury compounds are highly poisonous and toxic. In the US, they are banned for use in most cosmetic products, and in Canada they 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, plastics, 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 - sublimate. Let's take a closer look at this connection.
Formula and properties
Mercury chloride 2-valent is designated HgCl2. This compound is a white crystalline powder. At a temperature of 277˚С, it begins to melt, and at 304˚С, it begins to boil. Under normal conditions (25˚C), its density is 5.43 g/cm3. Mercury chloride sublimes easily, it is distinguished by noticeable volatility. The solubility of sublimate in water largely depends on its temperature. So, at 20 ° C, this figure 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 is able to dissolve in ether, acids, pyridine; in NaCl solution, this process is accompanied by the formation of complex compounds. As an electrolyte, HgCl2 is rather weak. In daylight, especially when in contact with organic compounds, this substance is easily reduced to monovalent chloride Hg2Cl2 (calomel) and metallic mercury.
Receive
In large quantities, mercury (II) chloride is currently produced only through direct synthesis from mercury and chlorine. The second way to obtain sublimate is to dissolve HgO in concentrated hydrochloric acid (HCl). In practice, it is used less frequently, mainly in the course of laboratory experiments. In the first case, mercury is heated in an atmosphere of chlorine to a very high temperature (about 340 ° C), after which it ignites and burns out with the formation of a bluish-white flame. The resulting vapors thicken as they cool and, depending on the production technology, form a fine powder or solid pieces.
Application
It is worth noting that mercuric chloride was the first Hg-based substance to be used as an antiseptic and disinfectant. In this respect, sublimate is highly effective, but at the same time it is verytoxic. It is able to be absorbed through the skin and mucous membranes and accumulate in the human body. Previously, when people were not yet aware of the danger posed by mercury chloride, it was used to cure skin diseases. Now in medicine it is used more for the disinfection of clothing, underwear, patient care items, etc. Since this substance is very poisonous, its solutions are often specially colored so that it is not mistakenly confused with other medicines.
In industry, mercury chloride is used in electroforming, wood preservation, thermal metallization and bronzing. Sublimate is used for the manufacture of batteries, paints for the underwater part of the hulls of marine vessels. It is used in leather tanning, lithography, photography, insecticide, etc.
