Mercury(II) chloride or mercuric chloride (archaically, corrosive sublimate) is the chemical compound of mercury and chlorine with the formula HgCl2. This white crystalline solid is a laboratory reagent and a molecular compound. Once used as a treatment for syphilis, it is no longer used for medicinal purposes because of mercury toxicity and the availability of superior treatments.
3D model (JSmol)
|Molar mass||271.52 g/mol|
|Appearance||colorless or white solid|
|Melting point||276 °C (529 °F; 549 K)|
|Boiling point||304 °C (579 °F; 577 K)|
|3.6 g/100 mL (0 °C) |
7.4 g/100 mL (20 °C)
48 g/100 mL (100 °C)
|Solubility||4 g/100 mL (ether) |
soluble in alcohol, acetone, ethyl acetate
slightly soluble in benzene, CS2, pyridine
|Acidity (pKa)||3.2 (0.2M solution)|
Refractive index (nD)
Std enthalpy of
|Safety data sheet||ICSC 0979|
| T+ (T+)|
|R-phrases (outdated)||R28, R34, R48/24/25, R50/53|
|S-phrases (outdated)||(S1/2), S36/37/39, S45, S60, S61|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Production and basic propertiesEdit
Mercuric chloride exists not as a salt composed of discrete ions, but rather is composed of linear triatomic molecules, hence its tendency to sublime. In the crystal, each mercury atom is bonded to two close chloride ligands with Hg—Cl distance of 2.38 Å; six more chlorides are more distant at 3.38 Å.
Mercuric 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) compounds such as the nitrate:
- HgNO3 + 2 HCl → HgCl2 + H2O + NO2,
Its solubility increases from 6% at 20 °C (68 °F) to 36% in 100 °C (212 °F). In the presence of chloride ions, it dissolves to give the tetrahedral coordination complex [HgCl4]2−.
- C2H2 + HCl → CH2=CHCl
For this application, the mercuric chloride is supported on carbon in concentrations of about 5 weight percent. This technology has been eclipsed by the thermal cracking of 1,2-dichloroethane. Other significant applications of mercuric chloride include its use as a depolarizer in batteries and as a reagent in organic synthesis and analytical chemistry (see below). It is being used in plant tissue culture for surface sterilisation of explants such as leaf or stem nodes.
As a chemical reagentEdit
Mercuric chloride is occasionally used to form an amalgam with metals, such as aluminium. Upon treatment with an aqueous solution of mercuric chloride, aluminium strips quickly become covered by a thin layer of the amalgam. Normally, aluminium is protected by a thin layer of oxide, thus making it inert. Once amalgamated, aluminium can undergo a variety of reactions. For example, upon removal of the oxide layer, the exposed aluminium will immediately react with water generating Al(OH)3 and hydrogen gas. Halocarbons react with amalgamated aluminium in the Barbier reaction. These alkylaluminium compounds are nucleophilic and can be used in a similar fashion to the Grignard reagent. Amalgamated aluminium is also used as a reducing agent in organic synthesis. Zinc is also commonly amalgamated using mercuric chloride.
Mercuric chloride may be used as a stabilising agent for chemicals and analytical samples. Care must be taken to ensure that detected mercuric chloride does not eclipse the signals of other components in the sample, such as is possible in gas chromatography.
Historical use in photographyEdit
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.
Historical use in preservationEdit
For 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". This was done to prevent the specimens' destruction by moths, mites and mold. Objects in drawers were protected by scattering crystalline mercuric chloride over them. It finds minor use in tanning, and wood was preserved by kyanizing (soaking in mercuric chloride). Mercuric chloride was one of the three chemicals used for railroad tie wood treatment between 1830 and 1856 in Europe and the United States. Limited railroad ties were treated in the United States until there were concerns over lumber shortages in the 1890s. The process was generally abandoned because mercuric chloride was water-soluble and not effective for the long term, as well as being highly poisonous. Furthermore, alternative treatment processes, such as copper sulfate, zinc chloride, and ultimately creosote; were found to be less toxic. Limited kyanizing was used for some railroad ties in the 1890s and early 1900s.
Historic use in medicineEdit
Mercuric chloride was used to disinfect wounds by Arab physicians in the Middle Ages. It continued to be used by Arab doctors into the twentieth century, until modern medicine deemed it unsafe for use.
Syphilis was frequently treated with mercuric chloride before the advent of antibiotics. It was inhaled, ingested, injected, and applied topically. Both mercuric-chloride treatment for syphilis and poisoning during the course of treatment were so common that the latter's symptoms were often confused with those of syphilis. This use of "salts of white mercury" is referred to in the English-language folk song "The Unfortunate Rake".
Yaws was treated with mercuric chloride (labeled as Corrosive Sublimate) before the advent of antibiotics. It was applied topically to alleviate ulcerative symptoms. Evidence of this is found in Jack London's book "The Cruise of the Snark" in the chapter entitled The Amateur M.D.
Historic use in crime and accidental poisoningsEdit
- In volume V of Alexandre Dumas' Celebrated Crimes, he recounts the history of Antoine François Desrues, who killed a noblewoman, Madame de Lamotte, with "corrosive sublimate".
- In one highly publicized case in 1920, "mercury bichloride" was reported to have caused the death of 25-year-old American silent-film star Olive Thomas. While vacationing in France and staying at the Hôtel Ritz in Paris, she accidentally (or perhaps intentionally) ingested the compound, which had been prescribed to her husband Jack Pickford in liquid topical form to treat his "chronic syphilis".
Mercuric chloride is extremely toxic, both acutely and as a cumulative poison.
- Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A22. ISBN 978-0-618-94690-7.
- Chisholm, Hugh, ed. (1911). . Encyclopædia Britannica. 7 (11th ed.). Cambridge University Press. p. 197.
- Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.
- Matthias Simon, Peter Jönk, Gabriele Wühl-Couturier, Stefan Halbach "Mercury, Mercury Alloys, and Mercury Compounds" in Ullmann's Encyclopedia of Industrial Chemistry 2006: Wiley-VCH, Weinheim. doi:10.1002/14356007.a16_269.pub2
- Foreman, W. T.; Zaugg, S. D.; Faires, L. M.; Werner, M. G.; Leiker, T. J.; Rogerson, P. F. (1992). "Analytical interferences of mercuric chloride preservative in environmental water samples: Determination of organic compounds isolated by continuous liquid-liquid extraction or closed-loop stripping". Environmental Science & Technology. 26 (7): 1307. doi:10.1021/es00031a004.
- Towler, J. (1864). Stereographic negatives and landscape photography. Chapter 28. In: The silver sunbeam: a practical and theoretical textbook of sun drawing and photographic printing. Retrieved on April 13, 2005.
- Goldberg, L. (1996). A history of pest control measures in the anthropology collections, national museum of natural history, Smithsonian Institution. JAIC 35(1) 23–43. Retrieved on April 17, 2005.
- Freeman, M.H. Shupe, T.F. Vlosky, R.P. Barnes, H.M. (2003). Past, present and future of the wood preservation industry Archived 2005-05-03 at the Wayback Machine. Forest Products Journal. 53(10) 8–15. Retrieved on April 17, 2005.
- Pg. 19-75 "Date Nails and Railroad Tie Preservation" (3 vol.; 560 p.), published in 1999 by the Archeology and Forensics Laboratory, University of Indianapolis; Jeffrey A. Oaks
- <History of Railroad Tie Preservation by Jeffrey A. Oaks, Univ. of Indiana, Pg. 20-30 and Pg. 64, Table I "Archived copy" (PDF). Archived from the original (PDF) on 2011-07-18. Retrieved 2009-01-14.CS1 maint: Archived copy as title (link) >
- Maillard, Adam P. Fraise, Peter A. Lambert, Jean-Yves (2007). Principles and Practice of Disinfection, Preservation and Sterilization. Oxford: John Wiley & Sons. p. 4. ISBN 978-0470755068.
- Pimple, K.D. Pedroni, J.A. Berdon, V. (2002, July 09). Syphilis in history Archived 2008-04-30 at the Wayback Machine. Poynter Center for the Study of Ethics and American Institutions at Indiana University-Bloomington. Retrieved on April 20, 2008.
- Dumas, Alexandre (1895). Celebrated Crimes Volume V: The Cenci. Murat. Derues. G. Barrie & sons. p. 250. Retrieved 30 June 2015 – via Google Books.
- "Bichloride of Mercury Killed Olive Thomas". The Toronto World. September 15, 1920. p. 6. Retrieved August 27, 2018.
- Foster, Charles (2000). Stardust and Shadows: Canadians in Early Hollywood, page 257. Toronto, Canada: Dundurn Press, 2000. ISBN 978-1550023480.
|Wikimedia Commons has media related to Mercury(II) chloride.|
- Agency for toxic substances and disease registry. (2001, May 25). Toxicological profile for Mercury. Retrieved on April 17, 2005.
- National institutes of health. (2002, October 31). Hazardous substances data bank: Mercuric chloride. Retrieved on April 17, 2005.
- Young, R.(2004, October 6). Toxicity summary for mercury. The risk assessment information system. Retrieved on April 17, 2005.
- ATSDR - ToxFAQs: Mercury
- ATSDR - Public Health Statement: Mercury
- ATSDR - Medical Management Guidelines (MMGs) for Mercury (Hg)
- ATSDR - Toxicological Profile: Mercury
- International Chemical Safety Card 0979
- National Pollutant Inventory - Mercury and compounds Fact Sheet
- NIOSH Pocket Guide to Chemical Hazards
- Mercury chloride toxicity - includes excerpts from research reports.