Mercury(II) iodide

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Mercury(II) iodide
Mercury(II)-iodide-xtal-3D-vdW-A.png
Mercury(II) iodide (α form)
Mercury(II)-iodide-xtal-3D-vdW-B.png
Mercury(II) iodide (β form)
Mercury iodide.jpg
α (right) and β (left) forms
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 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
Flammability code 0: Will not burn. E.g., water Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
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 noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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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[edit]

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[edit]

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[edit]

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[edit]

References[edit]

  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