Mercury(II) iodide (α form) | |
Mercury(II) iodide (β form) | |
β (left) and α (right) forms | |
Names | |
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IUPAC name Mercury(II) iodide | |
Other names | |
Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChemSpider | |
DrugBank | |
ECHA InfoCard | 100.028.976 |
EC Number |
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277788 | |
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
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) |
6 mg/100 mL | |
Solubility product (Ksp) | 2.9×10−29 [1] |
Solubility | slightly soluble in alcohol, ether, acetone, chloroform, ethyl acetate, CS2, olive oil, castor oil Soluble in excess KI(Potassium iodide) forming soluble complex K2[HgI4 ](Potassium tetraiodomercurate(II)) also known as Nessler's reagent Contents |
−128.6·10−6 cm3/mol | |
Refractive index (nD) | 2.455 |
Structure | |
Tetrahedral | |
Pharmacology | |
D08AK30 ( WHO ) | |
Hazards | |
GHS labelling: | |
Danger | |
H300, H310, H330, H373, H410 | |
P260, P262, P264, P270, P271, P273, P280, P284, P301+P310, P302+P350, P304+P340, P310, P314, P320, P321, P322, P330, P361, P363, P391, P403+P233, P405, P501 | |
NFPA 704 (fire 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 otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Mercury(II) iodide is a chemical compound with the molecular formula Hg I2. It is typically produced synthetically but can also be found in nature as the extremely rare mineral coccinite. Unlike the related mercury(II) chloride it is hardly soluble in water (<100 ppm).
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 displays thermochromism; when heated above 126 °C (400 K) it undergoes a phase transition, from the red alpha crystalline form to a pale yellow beta form. As the sample cools, it gradually reacquires its original colour. It has often been used for thermochromism demonstrations. [2] A third form, which is orange, is also known; this can be formed by recrystallisation and is also metastable, eventually converting back to the red alpha form. [3] The various forms can exist in a diverse range of crystal structures and as a result mercury(II) iodide possesses a surprisingly complex phase diagram. [4]
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, [5] used in some x-ray and gamma ray detection and imaging devices operating at room temperatures. [6]
In veterinary medicine, mercury(II) iodide is used in blister ointments in exostoses, bursal enlargement, etc. [ citation needed ]
It can appear as a precipitate in many reactions.
Silver iodide is an inorganic compound with the formula AgI. The compound is a bright yellow solid, but samples almost always contain impurities of metallic silver that give a grey colouration. The silver contamination arises because some samples of AgI can be highly photosensitive. This property is exploited in silver-based photography. Silver iodide is also used as an antiseptic and in cloud seeding.
An iodide ion is the ion I−. Compounds with iodine in formal oxidation state −1 are called iodides. In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. Worldwide, iodine deficiency affects two billion people and is the leading preventable cause of intellectual disability.
Potassium tetraiodomercurate(II) is an inorganic compound with the chemical formula K2[HgI4]. It consists of potassium cations and tetraiodomercurate(II) anions. It is the active agent in Nessler's reagent, used for detection of ammonia.
Lead(II) iodide is a chemical compound with the formula PbI
2. At room temperature, it is a bright yellow odorless crystalline solid, that becomes orange and red when heated. It was formerly called plumbous iodide.
Classical qualitative inorganic analysis is a method of analytical chemistry which seeks to find the elemental composition of inorganic compounds. It is mainly focused on detecting ions in an aqueous solution, therefore materials in other forms may need to be brought to this state before using standard methods. The solution is then treated with various reagents to test for reactions characteristic of certain ions, which may cause color change, precipitation and other visible changes.
Thermochromism is the property of substances to change color due to a change in temperature. A mood ring is an excellent example of this phenomenon, but thermochromism also has more practical uses, such as baby bottles which change to a different color when cool enough to drink, or kettles which change color when water is at or near boiling point. Thermochromism is one of several types of chromism.
Cadmium chloride is a white crystalline compound of cadmium and chloride, with the formula CdCl2. This salt is a hygroscopic solid that is highly soluble in water and slightly soluble in alcohol. The crystal structure of cadmium chloride (described below), is a reference for describing other crystal structures. Also known are CdCl2•H2O and the hemipentahydrate CdCl2•2.5H2O.
Tin(II) chloride, also known as stannous chloride, is a white crystalline solid with the formula SnCl2. It forms a stable dihydrate, but aqueous solutions tend to undergo hydrolysis, particularly if hot. SnCl2 is widely used as a reducing agent (in acid solution), and in electrolytic baths for tin-plating. Tin(II) chloride should not be confused with the other chloride of tin; tin(IV) chloride or stannic chloride (SnCl4).
Copper(I) iodide is an inorganic compound with the chemical formula CuI. It is also known as cuprous iodide. It is useful in a variety of applications ranging from organic synthesis to cloud seeding.
Mercury(II) thiocyanate (Hg(SCN)2) is an inorganic chemical compound, the coordination complex of Hg2+ and the thiocyanate anion. It is a white powder. It will produce a large, winding "snake" when ignited, an effect known as the Pharaoh's serpent.
Thallium(I) iodide is a chemical compound with the formula . It is unusual in being one of the few water-insoluble metal iodides, along with , , , , and .
Beryllium chloride is an inorganic compound with the formula BeCl2. It is a colourless, hygroscopic solid that dissolves well in many polar solvents. Its properties are similar to those of aluminium chloride, due to beryllium's diagonal relationship with aluminium.
Cobalt(II) iodide or cobaltous iodide are the inorganic compounds with the formula CoI2 and the hexahydrate CoI2(H2O)6. These salts are the principal iodides of cobalt.
Few compounds of californium have been made and studied. The only californium ion that is stable in aqueous solutions is the californium(III) cation. The other two oxidation states are IV (strong oxidizing agents) and II (strong reducing agents). The element forms a water-soluble chloride, nitrate, perchlorate, and sulfate and is precipitated as a fluoride, oxalate or hydroxide. If problems of availability of the element could be overcome, then CfBr2 and CfI2 would likely be stable.
Iron(II) iodide is an inorganic compound with the chemical formula FeI2. It is used as a catalyst in organic reactions.
Nickel(II) thiocyanate is a coordination polymer with formula Ni(SCN)2. It is a green-brown solid and its crystal structure was determined first in 1982.
Europium(II) iodide is the iodide salt of divalent europium cation.
Praseodymium diiodide is a chemical compound with the empirical formula of PrI2, consisting of praseodymium and iodine. It is an electride, with the ionic formula of Pr3+(I−)2e−, and therefore not a true praseodymium(II) compound.
Thulium(III) iodide is an iodide of thulium, with the chemical formula of TmI3. Thulium(III) iodide is used as a component of metal halide lamps.
Lutetium compounds are compounds formed by the lanthanide metal lutetium (Lu). In these compounds, lutetium generally exhibits the +3 oxidation state, such as LuCl3, Lu2O3 and Lu2(SO4)3. Aqueous solutions of most lutetium salts are colorless and form white crystalline solids upon drying, with the common exception of the iodide. The soluble salts, such as nitrate, sulfate and acetate form hydrates upon crystallization. The oxide, hydroxide, fluoride, carbonate, phosphate and oxalate are insoluble in water.