Mercury(I) chloride

• Calomel
• Dimercury dichloride

Colorless odorless crystals

Fixed

7.15 g · cm -3

400 ° C.

0.3 MPa (50 ° C)

Very poor in water ( 2.3 mg · l-1 at 20 ° C)

Attention

0.1 mg · m-3

• 210 mg · kg -1 ( LD50, rat, oral)
• 1500 mg · kg -1 ( LD50, rat, transdermal)

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Mercury (I ) chloride (. Calomel, from ancient Greek καλός kalos ' beautiful ' and μέλας melas, black', ie " beautiful black "; formerly sweet mercury, mercurous or Quecksilberhornerz ) is a colorless solid which was in water only very be little dissolves and sublimates at about 380 ° C. The molecular formula is Hg2Cl2.

In the light it changes color gradually to dark black ( hence the name calomel ), because it decays by disproportionation to elemental mercury and mercury (II ) chloride.

Occurrence

Mercury (I ) chloride occurs naturally as a rare mineral calomel before, a dark gray mineral that can be gray -yellow to light yellow at higher mercury (I ) chloride shares. Even more rarely you will find very little pure mercury (I ) chloride crystals in geodes.

Use

Mercury (I ) chloride is used in calomel electrodes for potentiometric, for pest control in pyrotechnics for green glowing torches in porcelain painting for the application of gold and as a catalyst.

Medicine

Because it is not absorbed by the body because of its extremely low solubility in water, it found numerous applications in medicine: against inflammation in the nose and throat, as a laxative, to stimulate the biliary function, against vomiting and diarrhea, dropsy, spleen, liver, lung disease and against syphilis, and externally against walleye, ulcers and warts.

It was also used until the 1990s as a spermicide in chemical contraceptives.