article

Mercury(II) chloride
General
Systematic name Mercury(II) chloride
Mercury dichloride
Other names Mercuric chloride
Corrosive sublimate
Molecular formula HgCl2
Molar mass 271.52 g/mol
Appearance white solid
CAS number *
Properties
Density and phase 6.5 g/cm3, solid
Solubility in water 7.4 g/100 ml (20 °C)
Solubility in ethanol 33 g/100 ml (25 °C)
Melting point 277 °C
Boiling point 302 °C
Structure
Molecular shape linear
Coordination
geometry 		linear
Crystal structure ?
Dipole moment zero
Hazards
MSDS External MSDS
EU classification Very toxic (T+)
Dangerous for
the environment (N)
NFPA 704
R-phrases , , ,
S-phrases , , , ,
Flash point non-flammable
Supplementary data page
Structure and
properties 		n, εr, etc.
Thermodynamic
data 		Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Related compounds
Other anions Mercury(II) fluoride
Mercury(II) bromide
Mercury(II) iodide
Other cations Zinc chloride
Cadmium chloride
Mercury(I) chloride
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Chemical infobox

Mercury(II) chloride (also called mercuric chloride and corrosive sublimate) is a poisonous white soluble crystalline sublimate of mercury. It was formerly used in insecticides, batteries; as an antiseptic, disinfectant, preservative, in metallurgy and as a photographic fixitive. Mercuric chloride is one of the most toxic forms of mercury because it easily forms organomercury complexes with proteins.

Production

Mercury(II) chloride is obtained by the action of chlorine on mercury or mercury(I) chloride, by the addition of hydrochloric acid to a hot, concentrated solution of mercury(I) nitrate,
HgNO3 + 2HCl → HgCl2 + H2O + NO2,
or by heating a mixture of mercury(II) sulfate and sodium chloride. The mercuric chloride then sublimes and condenses in the form of small rhombic crystals.

Applications

Mercury(II) chloride was used as a photographic intensifier to produce positive pictures in the collodion process of the 1800s. When applied to a negative, the mercury(II) chloride whitens and thickens the image, thereby increasing the opacity of the shadows and creating the illusion of a positive image (Towler, 1864).

The preservation of anthropological and biological specimens during the late 19th and early 20th centuries. Objects were dipped in or were painted with a mercuric solution. Objects in drawers were protected by scattering crystalline mercuric chloride over them (Goldberg, 1996).

Syphilis was frequently treated with mercuric chloride before the advent of antibiotics. It was inhaled, ingested, injected and applied topically. Poisoning was so common that its symptoms were confused with those of syphilis (Pimple, 2004).

Mercury(II) chloride is used in the manufacture of calomel, chemical reagents, metallurgy, tanning, as a catalyst for vinyl chloride and in electroplating. Wood was preserved by kyanizing (soaking in mercuric chloride) beginning in 1848 (Freeman, 2003).

Toxicity

Mercury(II) chloride is highly toxic and corrosive. Once absorbed into the bloodstream, inorganic mercury combines with proteins in the plasma or enters the red blood cells. It does not readily pass into the brain or fetus but may enter into other body organs. The liver is a major site of metabolism for mercury, and all mercury absorbed from the stomach and intestine is carried in blood directly to the liver. It accumlates in the kidneys, and may cause severe damage. Poisoning can result from inhalation, ingestion, or absorption through the skin.

Inhalation may result in corrosive bronchitis, interstitial pneumonitis, and death. Systemic effects following inhalation exposure may include shock, renal disorders, and central nervous system effects characterized by lethargy and neurobehavioral effects (insomnia, loss of memory, excitability, etc). Chronic exposure to low levels of vapor may result in central nervous system effects including fatigue, tremors, and gingivitis. As exposure increases, the frequency and magnitude of muscle tremors increase and are accompanied by personality and behavioral changes (memory loss, excitability, depression, and hallucinations).

Ingestion may cause severe gastrointestinal irritation, renal failure, and death with acute lethal doses in humans ranging from 1 to 4 g. The toxic effects are usually evident within 10-15 minutes of ingestion. Death can occur within 24 hours, resulting from shock, renal damage, severe gastrointestinal damage or kidney failure. Chronic symptoms include increased salivation, bleeding gums and loosening of the teeth.

Dermal contact with mercuric chloride may cause dermatitis and neurological effects. Acrodynia occurs in children and is characterised by a generalised body rash. Other symptoms include swelling and irritation of the hands, feet, cheeks and nose, hair loss, irritability, insomnia, and profuse perspiration which may lead to dehydration. Chronic exposure through absorption is usually the result of regular applications of topical ointments containing mercuric chloride.

See also

corrosive, mercury(I) chloride

References

External links

Mercury compounds | Chlorides | Metal halides

Chlorid rtuťnatý | Quecksilber(II)-chlorid | 塩化水銀(II) | Хлорид ртути

 

This article is licensed under the GNU Free Documentation License. It uses material from the "Mercury(II) chloride".

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