| Identification | More | [Name]
MERCURY(II) IODIDE | [CAS]
7774-29-0 | [Synonyms]
MERCURIC IODIDE
MERCURIC IODIDE RED
MERCURY(+2)IODIDE, RED
MERCURY (II) BINIODIDE, RED
MERCURY(II) IODIDE
MERCURY(II) IODIDE RED
MERCURY IODIDE
VALSER'S REAGENT
alpha-mercury(ii)iodide
HgI2
Hydrargyrum bijodatum
hydrargyrumbijodatum
mercuriciodide,[solution]
Mercury biniodide
Mercury iodide (HgI2)
mercurybiniodide
mercuryiodide(hgi2)
Red mercuric iodide
redmercuriciodide
Mercury iodide red
| [EINECS(EC#)]
231-873-8 | [Molecular Formula]
HgI2 | [MDL Number]
MFCD00011044 | [Molecular Weight]
454.4 | [MOL File]
7774-29-0.mol |
| Chemical Properties | Back Directory | [Appearance]
Mecuric iodide is a heavy, scarlet red, odorless, crystalline solid. It may be shipped as a red solution.
It turns to a yellow powder @ 127℃ and red upon cooling | [Melting point ]
259 °C(lit.) | [Boiling point ]
354 °C(lit.) | [density ]
6.36 | [vapor pressure ]
0.006 hPa (80 °C) | [Fp ]
350°C subl. | [storage temp. ]
Store at RT. | [solubility ]
potassium iodide solution: passes test
| [form ]
beads
| [color ]
White | [Specific Gravity]
6.271 | [Odor]
Odorless | [PH]
6-7 (50g/l, H2O, 20℃)(slurry) | [Stability:]
Stable. Incompatible with strong oxidizing agents, potassium, sodium, interhalogens. Light-sensitive. | [Water Solubility ]
Insoluble inwater. Slightly soluble in alcohol, ether, acetone, chloroform, ethyl acetate, olive oil and castor oil. | [Sensitive ]
Light Sensitive | [Merck ]
14,5879 | [Solubility Product Constant (Ksp)]
pKsp: 28.54 | [Exposure limits]
ACGIH: TWA 0.025 mg/m3; TWA 0.01 ppm (Skin)
NIOSH: IDLH 10 mg/m3; TWA 0.05 mg/m3; Ceiling 0.1 mg/m3 | [CAS DataBase Reference]
7774-29-0(CAS DataBase Reference) | [EPA Substance Registry System]
Mercuric iodide (7774-29-0) |
| Safety Data | Back Directory | [Hazard Codes ]
T+,N | [Risk Statements ]
R26/27/28:Very Toxic by inhalation, in contact with skin and if swallowed .
R33:Danger of cumulative effects.
R50/53:Very Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment . | [Safety Statements ]
S13:Keep away from food, drink and animal feeding stuffs .
S28:After contact with skin, wash immediately with plenty of ... (to be specified by the manufacturer) .
S45:In case of accident or if you feel unwell, seek medical advice immediately (show label where possible) .
S60:This material and/or its container must be disposed of as hazardous waste .
S61:Avoid release to the environment. Refer to special instructions safety data sheet . | [RIDADR ]
UN 2025 6.1/PG 2
| [WGK Germany ]
3
| [RTECS ]
OW5250000
| [F ]
8 | [TSCA ]
Yes | [HazardClass ]
6.1 | [PackingGroup ]
II | [HS Code ]
28521000 | [Safety Profile]
A poison. When heated
to decomposition it emits very toxic fumes
of Hg and I-. See also MERCURY(I1)
IODIDE. | [Hazardous Substances Data]
7774-29-0(Hazardous Substances Data) | [Toxicity]
LD50 orally in Rabbit: 18 mg/kg LD50 dermal Rat 75 mg/kg |
| Hazard Information | Back Directory | [General Description]
A scarlet-red odorless tasteless powder. Sensitive to light. Insoluble in water and sinks in water. At elevated temperatures turns yellow but turns back to red upon cooling. Poison. | [Reactivity Profile]
MERCURY IODIDE(7774-29-0) is a mild reducing agent. Reacts with sodium azide to form mercury(II) azide, which is shock, friction, and heat sensitive. Incompatible with acetylene, ammonia, chlorine dioxide, azides, chlorine trifluoride, calcium (because of amalgam formation), sodium carbide, lithium, rubidium, copper . | [Air & Water Reactions]
Insoluble in water. | [Hazard]
Highly toxic by ingestion, inhalation, and
skin absorption; strong irritant. | [Health Hazard]
All forms of exposure to this compound are hazardous. Acute systemic mercurialism may be fatal within a few minutes; death by uremic poisoning is usually delayed 5-12 days. Acute poisoning has resulted from inhaling dust concentrations of 1.2-8.5 mg/m 3 of air; symptoms include tightness and pain in chest, coughing, and difficulty in breathing. Ingestion causes necrosis, pain, vomiting, and severe purging. Contact with eyes causes ulceration of conjunctiv a and cornea. Contact with skin causes irritation and possible dermatitis; systemic poisoning can occur by absorption through skin. | [Potential Exposure]
Mercuric iodide is used in medicine
and in analytical chemistry. | [Fire Hazard]
Special Hazards of Combustion Products: Fumes from fire may contain toxic mercury vapor. | [First aid]
If this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. If this chemical contacts the
skin, remove contaminated clothing and wash immediately
with soap and water. Seek medical attention immediately.
If this chemical has been inhaled, remove from exposure,
begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if
heart action has stopped. Transfer promptly to a medical
facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce
vomiting. Do not make an unconscious person vomit.
Antidotes and Special Procedures for authorized medical
personnel: The drug NAP has been used to treat mercury
poisoning, with mixed success.
| [Incompatibilities]
Violent reaction with active metals;
potassium, sodium, acids, chlorine trifluoride. Inorganic
mercury compounds are incompatible with acetylene,
ammonia, chlorine dioxide; azides, calcium (amalgam formation), sodium carbide, lithium, rubidium, copper.
Mercury iodide is a mild reducing agent. Keep away from
oxidizers. Reacts with sodium azide to form mercury(II)
azide, which is shock-, friction-, and heat-sensitive.
Incompatible with acetylene, ammonia, chlorine dioxide,
azides, chlorine trifluoride, calcium (because of amalgam
formation), sodium carbide, lithium, rubidium, copper
(NIOSH, 1997) | [Description]
Mercuric iodide is a heavy, scarlet red, odorless, crystalline solid. It may be shipped as a red solution. It turns to a yellow powder at 127℃ and red upon cooling. Molecular weight= 454.40;Boiling point=(sublimes) 354℃; Freezing/Melting point=259℃. Hazard Identification (based on NFPA-704 M Rating System): Health 3, Flammability 0, Reactivity 0. Slightly soluble in water. | [Chemical Properties]
Mecuric iodide is a heavy, scarlet red, odorless, crystalline solid. It may be shipped as a red solution.
It turns to a yellow powder @ 127℃ and red upon cooling | [Chemical Properties]
Red Solid | [Definition]
ChEBI: Mercury diiodide is a mercury coordination entity composed of mercury and iodine with formula HgI2. | [storage]
Color Code—Blue: Health Hazard/Poison: Store in a secure poison location. Prior to working with this chemical you should be trained on its proper handling and storage. Mercuric iodide must be stored to avoid contact with chlorine trifluoride, sodium, and potassium, since violent reactions occur. Store in tightly closed containers in a cool, well-ventilated area away from light, acids, and heat. Protect containers from physical damage. | [Shipping]
This compound requires a shipping label of “POISONOUS/TOXIC MATERIALS” (solution). It falls in Hazard Class 6.1 and Packing Group II. | [Purification Methods]
Crystallise it from MeOH or EtOH and wash it repeatedly with distilled water (solubility is 0.006% at ~25o). It has also been mixed thoroughly with excess 0.001M iodine solution, filtered, washed with cold distilled water, rinsed with EtOH and Et2O, and dried in air. It changes colour reversibly to yellow at ~130o. [Friend Nature 109 341 1922.] POISONOUS. |
| Questions And Answer | Back Directory | [Physical Properties]
Exists in two allotropic forms: red tetragonal allotropic modification (alpha form) and the yellow rhombic modification (beta form).
The red iodide has a density 6.36 g/cm3 at 25°C; transforms to yellow form at 127°C; also converts to yellow form at –180°C; slightly soluble in water (100 mg/L at 25°C); moderately soluble in acetone and alcohol.
The yellow iodide has a density of 6.09 g/cm3 at 27°C; melts at 259°C; vaporizes at 354°C; practically insoluble in water; low-to-moderately soluble in alcohol, benzene and other organic solvents.
| [Uses]
Mercury(II) iodide is used as an analytical reagent, in Nesslers reagent for the analysis of ammonia. The compound also is used in ointments for the treatment of skin diseases.
| [Preparation]
Mercury(II) iodide is precipitated in its yellow form by adding a stoichiometric amount of potassium iodide to an aqueous solution of mercury(II) salt (e.g., HgCl2):
Hg2+ + 2I¯ → HgI2
The yellow precipitate rapidly turns red and dissolves in solution when excess potassium iodide is added.
Also, mercury (II) iodide is formed when mercury is rubbed with iodine moistened with ethanol.
| [Reactions]
Mercury(II) iodide reacts with excess iodide ion forming complex tetraiodomercurate(II) ion, [HgI4]2¯:
HgI2 + 2I¯ → [HgI4]2¯
In caustic soda or caustic potash solution, mercury(II) iodide forms complex salts, Na2HgI4 and K2HgI4, respectively. Alkaline solution of this complex in excess potassium hydroxide is known as Nessler’s reagent, used to analyze ammonia. The reaction of Nessler’s reagent with ammonia may be written as:
2[HgI4]2¯ + NH3 + 3OH¯ → I—Hg—O—Hg—NH3 +7I¯ + 2H2O
Similar complexes of silver, copper and other metals are known. Some of them change colors on heating and are used in heat-sensitive paints and applied to machine parts made out of brass or iron:
2Cu2+ + Hg2+ + 6I¯ → Cu2HgI4 + I2
(red)
2Ag+ + Hg2+ + 6I¯ → Ag2HgI4 + I2
(yellow)
In general, mercury(II) iodide forms neutral complexes of compositions M2(HgI4) and M(HgI3) with alkali and alkaline metal iodides.
When heated with dilute caustic potash solution, a yellow brown powder of composition HgI2•3HgO is obtained.
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