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Mercury(II) iodide

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Title: Mercury(II) iodide  
Author: World Heritage Encyclopedia
Language: English
Subject: Red mercury, Potassium tetraiodomercurate(II), Mercury(II) bromide, Mercury (element), Mercury(I) iodide
Collection: Iodides, Mercury Compounds, Metal Halides, Semiconductor Materials
Publisher: World Heritage Encyclopedia

Mercury(II) iodide

Mercury(II) iodide

Mercury(II) iodide (α form)

Mercury(II) iodide (β form)

β (left) and α (right) forms
IUPAC name
Mercury diiodide
Other names
Mercuric iodide
Red mercury (α form only)
ATC code D08
ChemSpider  Y
DrugBank  Y
Jmol-3D images Image
Molar mass 454.40 g/mol
Appearance orange-red powder
Odor odorless
Density 6.36 g/cm3
Melting point 259 °C (498 °F; 532 K)
Boiling point 350 °C (662 °F; 623 K)
0.006 g/100 mL
Solubility slightly soluble in alcohol, ether, acetone, chloroform, ethyl acetate, CS2, olive oil, castor oil
Very toxic (T+)
Dangerous for the environment (N)
R-phrases R50/53
S-phrases (S1/2), S13, S28, S45, S60, S61
NFPA 704
Flash point Non-flammable
Related compounds
Other anions
Mercury(II) fluoride
Mercury(II) chloride
Mercury(II) bromide
Other cations
Zinc iodide
Cadmium iodide
Related compounds
Mercury(I) iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 Y  (: Y/N?)

Mercury(II) iodide (HgI2) is a chemical compound with an appearance of red-orange crystals. Unlike mercury(II) chloride it is hardly soluble in water (<100 ppm).

Conditions/substances to avoid include: heat, light, bromides, chlorides, ammonia, alkalis, cyanides, copper salts, lead salts, iodoform and hydrogen peroxide.


  • Properties 1
  • Production 2
  • Uses 3
  • See also 4
  • References 5


Mercury(II) iodide displays thermochromism; when heated above 126 °C, it undergoes phase transition from the alpha crystalline form to a pale yellow beta form. As the sample cools, it gradually reacquires its original color. It is often used for thermochromism demonstrations.[1]


Mercury(II) iodide is produced by adding an aqueous solution of potassium iodide to an aqueous solution of mercury(II) chloride with stirring; the precipitate is filtered off, washed and dried at 70 °C.


Mercury(II) iodide is used for preparation of Nessler's reagent, used for detection of presence of ammonia.

Mercury(II) iodide is a semiconductor material, used in some x-ray and gamma ray detection and imaging devices operating at room temperatures.[2]

Mercury(II) iodide can be found extremely rarely in nature as mineral coccinite.

In veterinary medicine, mercury(II) iodide is used in blister ointments in exostoses, bursal enlargement, etc.

It can appear as a precipitate in many reactions.

See also


  1. ^ Thermochromism: Mercury(II) Iodide. Retrieved on 2011-06-02.
  2. ^ Simage, Oy U.S. Patent 6,509,203 Semiconductor imaging device and method for producing same, Issue date: Jan 21, 2003
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