| Mercury(II) iodide | |
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Mercury(II) iodide (α form)
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Mercury(II) iodide (β form)
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α (right) and β (left) forms
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Mercury diiodide |
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Other names
Mercuric iodide |
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| Identifiers | |
| CAS number | 7774-29-0 |
| ChemSpider | 22893 |
| UNII | R03O05RB0P |
| DrugBank | DB04445 |
| ChEBI | CHEBI:49659 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | HgI2 |
| Molar mass | 454.40 g/mol |
| Appearance | orange-red powder |
| Density | 6.36 g/cm3 |
| Melting point |
259 °C |
| Boiling point |
350 °C |
| Solubility in water | 0.06 g/L |
| 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
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| 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 |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 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.
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 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.
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