Mercury(II) iodide

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Mercury(II) iodide

Mercury(II) iodide (α form)

Mercury(II) iodide (β form)

α (right) and β (left) forms
IUPAC name

Mercury diiodide

Other names

Mercuric iodide
Red mercury (α form only)

Identifiers
CAS number 7774-29-0 YesY
PubChem 24485
ChemSpider 22893 YesY
UNII R03O05RB0P YesY
DrugBank DB04445
ChEBI CHEBI:49659 YesY
ATC code D08AK30
Jmol-3D images {{#if:I[Hg]I|Image 1
Properties
Molecular formula HgI2
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
Solubility in water 0.006 g/100 mL
Solubility slightly soluble in alcohol, ether, acetone, chloroform, ethyl acetate, CS2, olive oil, castor oil
Refractive index (nD) 2.455
Structure
Crystal structure tetrehedral
Hazards
EU Index 080-002-00-6
EU classification Very toxic (T+)
Dangerous for the environment (N)
R-phrases R26/27/28, R33, R50/53
S-phrases (S1/2), S13, S28, S45, S60, S61
NFPA 704
0
3
0
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
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

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

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]

Production

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.

Uses

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

References

  1. ↑ Thermochromism: Mercury(II) Iodide. Jchemed.chem.wisc.edu. 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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