Names | |
---|---|
IUPAC name Cadmium fluoride | |
Other names Cadmium(II) fluoride, Cadmium difluoride | |
Identifiers | |
3D model (JSmol) | |
ChemSpider | |
ECHA InfoCard | 100.029.293 |
EC Number |
|
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
| |
| |
Properties | |
CdF2 | |
Molar mass | 150.41 g/mol |
Appearance | grey or white-grey crystals |
Density | 6.33 g/cm3, solid |
Melting point | 1,110 °C (2,030 °F; 1,380 K) |
Boiling point | 1,748 °C (3,178 °F; 2,021 K) |
4.35 g/100 mL | |
Solubility product (Ksp) | 0.00644 [1] |
Solubility | soluble in acid insoluble in ethanol alcohol and liquid ammonia |
-40.6·10−6 cm3/mol | |
Structure | |
Fluorite (cubic), cF12 | |
Fm3m, No. 225 | |
Thermochemistry | |
Std enthalpy of formation (ΔfH⦵298) | -167.39 ± 0.23 kcal. mole-1 at 298.15 (K, C?) |
Gibbs free energy (ΔfG⦵) | -155.4 ± 0.3 kcal. mole-1 at 298.15 (K, C?) |
Hazards | |
GHS labelling: | |
Danger | |
H301, H330, H340, H350, H360, H372, H410 | |
P201, P202, P260, P264, P270, P271, P273, P281, P284, P301+P310, P304+P340, P308+P313, P310, P314, P320, P321, P330, P391, P403+P233, P405, P501 | |
NIOSH (US health exposure limits): | |
PEL (Permissible) | [1910.1027] TWA 0.005 mg/m3 (as Cd) [2] |
REL (Recommended) | Ca [2] |
IDLH (Immediate danger) | Ca [9 mg/m3 (as Cd)] [2] |
Related compounds | |
Other anions | Cadmium chloride, Cadmium bromide Cadmium iodide |
Other cations | Zinc fluoride, Mercury(II) fluoride, Copper(II) fluoride, Silver(II) fluoride, Calcium fluoride, Magnesium fluoride |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Cadmium fluoride (CdF2) is a mostly water-insoluble source of cadmium used in oxygen-sensitive applications, such as the production of metallic alloys. In extremely low concentrations (ppm), this and other fluoride compounds are used in limited medical treatment protocols. Fluoride compounds also have significant uses in synthetic organic chemistry. [3] The standard enthalpy has been found to be -167.39 kcal. mole−1 and the Gibbs energy of formation has been found to be -155.4 kcal. mole−1, and the heat of sublimation was determined to be 76 kcal. mole−1. [4] [5]
Cadmium fluoride is prepared by the reaction of gaseous fluorine or hydrogen fluoride with cadmium metal or its salts, such as the chloride, oxide, or sulfate.
It may also be obtained by dissolving cadmium carbonate in 40% hydrofluoric acid solution, evaporating the solution and drying in a vacuum at 150 °C.
Another method of preparing it is to mix cadmium chloride and ammonium fluoride solutions, followed by crystallization. The insoluble cadmium fluoride is filtered from solution. [6]
Cadmium fluoride has also been prepared by reacting fluorine with cadmium sulfide. This reaction happens very quickly and forms nearly pure fluoride at much lower temperatures than other reactions used. [7]
CdF2 can be transformed into an electronic conductor when doped with certain rare earth elements or yttrium and treated with cadmium vapor under high temperature conditions. This process creates blue crystals with varying absorption coefficients depending on the concentrations of the dopant. A proposed mechanism explains that the conductivity of these crystals can be explained by a reaction of Cd atoms with Interstitial F− ions. This creates more CdF2 molecules and releases electrons which are weakly bonded to trivalent dopant ions resulting in n-type conductivity and a hydrogenic donor level. [8]
Cadmium fluoride, like all cadmium compounds, is toxic and should be used with care.
Cadmium fluoride can cause potential health issues if it is not handled properly. It can cause irritation to the skin and the eyes, so gloves and protective eyewear are advised. The MSDS, or Material Safety Data Sheet, also includes warnings for ingestion and inhalation. Under acidic conditions, at high temperatures, and in moist environments, hydrogen fluoride and cadmium vapors may be released into the air. Inhalation may cause irritation of the respiratory system as well as congestion, fluorosis, and even pulmonary edema in extreme cases. Cadmium fluoride also has the same potential hazards caused by cadmium and fluoride. [9]
Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colorless, acidic and highly corrosive. A common concentration is 49% (48-52%) but there are also stronger solutions and pure HF has a boiling point near room temperature. It is used to make most fluorine-containing compounds; examples include the commonly used pharmaceutical antidepressant medication fluoxetine (Prozac) and the material PTFE (Teflon). Elemental fluorine is produced from it. It is commonly used to etch glass and silicon wafers.
Calcium fluoride is the inorganic compound of the elements calcium and fluorine with the formula CaF2. It is a white solid that is practically insoluble in water. It occurs as the mineral fluorite (also called fluorspar), which is often deeply coloured owing to impurities.
Cadmium sulfide is the inorganic compound with the formula CdS. Cadmium sulfide is a yellow salt. It occurs in nature with two different crystal structures as the rare minerals greenockite and hawleyite, but is more prevalent as an impurity substituent in the similarly structured zinc ores sphalerite and wurtzite, which are the major economic sources of cadmium. As a compound that is easy to isolate and purify, it is the principal source of cadmium for all commercial applications. Its vivid yellow color led to its adoption as a pigment for the yellow paint "cadmium yellow" in the 18th century.
Oxygen difluoride is a chemical compound with the formula OF2. As predicted by VSEPR theory, the molecule adopts a bent molecular geometry. It is a strong oxidizer and has attracted attention in rocketry for this reason. With a boiling point of −144.75 °C, OF2 is the most volatile (isolable) triatomic compound. The compound is one of many known oxygen fluorides.
Nickel(II) fluoride is the chemical compound with the formula NiF2. It is an ionic compound of nickel and fluorine and forms yellowish to green tetragonal crystals. Unlike many fluorides, NiF2 is stable in air.
Beryllium fluoride is the inorganic compound with the formula Be F2. This white solid is the principal precursor for the manufacture of beryllium metal. Its structure resembles that of quartz, but BeF2 is highly soluble in water.
Iodine pentafluoride is an interhalogen compound with chemical formula IF5. It is one of the fluorides of iodine. It is a colorless liquid, although impure samples appear yellow. It is used as a fluorination reagent and even a solvent in specialized syntheses.
Nitryl fluoride, NO2F, is a colourless gas and strong oxidizing agent, which is used as a fluorinating agent and has been proposed as an oxidiser in rocket propellants (though never flown).
Iron(II) fluoride or ferrous fluoride is an inorganic compound with the molecular formula FeF2. It forms a tetrahydrate FeF2·4H2O that is often referred to by the same names. The anhydrous and hydrated forms are white crystalline solids.
Cobalt(II) fluoride is a chemical compound with the formula (CoF2). It is a pink crystalline solid compound which is antiferromagnetic at low temperatures (TN=37.7 K) The formula is given for both the red tetragonal crystal, (CoF2), and the tetrahydrate red orthogonal crystal, (CoF2·4H2O). CoF2 is used in oxygen-sensitive fields, namely metal production. In low concentrations, it has public health uses. CoF2 is sparingly soluble in water. The compound can be dissolved in warm mineral acid, and will decompose in boiling water. Yet the hydrate is water-soluble, especially the di-hydrate CoF2·2H2O and tri-hydrate CoF2·3H2O forms of the compound. The hydrate will also decompose with heat.
Silver(II) fluoride is a chemical compound with the formula AgF2. It is a rare example of a silver(II) compound - silver usually exists in its +1 oxidation state. It is used as a fluorinating agent.
Iron(III) fluoride, also known as ferric fluoride, are inorganic compounds with the formula FeF3(H2O)x where x = 0 or 3. They are mainly of interest by researchers, unlike the related iron(III) chloride. Anhydrous iron(III) fluoride is white, whereas the hydrated forms are light pink.
Copper(II) fluoride is an inorganic compound with the chemical formula CuF2. The anhydrous form is a white, ionic, crystalline, hygroscopic salt with a distorted rutile-type crystal structure, similar to other fluorides of chemical formulae MF2 (where M is a metal). The dihydrate, CuF2·2H2O, is blue in colour.
Antimony pentafluoride is the inorganic compound with the formula SbF5. This colourless, viscous liquid is a strong Lewis acid and a component of the superacid fluoroantimonic acid, formed upon mixing liquid HF with liquid SbF5 in 1:1 ratio. It is notable for its strong Lewis acidity and the ability to react with almost all known compounds.
Hydrogen fluoride (fluorane) is an inorganic compound with chemical formula HF. It is a very poisonous, colorless gas or liquid that dissolves in water to yield an aqueous solution termed hydrofluoric acid. It is the principal industrial source of fluorine, often in the form of hydrofluoric acid, and is an important feedstock in the preparation of many important compounds including pharmaceuticals and polymers, e.g. polytetrafluoroethylene (PTFE). HF is also widely used in the petrochemical industry as a component of superacids. Due to strong and extensive hydrogen bonding, it boils at near room temperature, much higher than other hydrogen halides.
Xenon difluoride is a powerful fluorinating agent with the chemical formula XeF
2, and one of the most stable xenon compounds. Like most covalent inorganic fluorides it is moisture-sensitive. It decomposes on contact with water vapor, but is otherwise stable in storage. Xenon difluoride is a dense, colourless crystalline solid.
Cadmium nitrate describes any of the related members of a family of inorganic compounds with the general formula Cd(NO3)2·xH2O. The most commonly encountered form being the tetrahydrate.The anhydrous form is volatile, but the others are colourless crystalline solids that are deliquescent, tending to absorb enough moisture from the air to form an aqueous solution. Like other cadmium compounds, cadmium nitrate is known to be carcinogenic. According to X-ray crystallography, the tetrahydrate features octahedral Cd2+ centers bound to six oxygen ligands.
Cadmium tetrafluoroborate is an ionic, chemical compound with the formula Cd(BF4)2. It is a crystalline solid, which is colorless and odorless. Cadmium tetrafluoroborate is most frequently used in the industrial production of high-strength steels, its purpose being to prevent hydrogen absorption, a source of post-production cracking of the metal, in the treated steels. Another application of the chemistry of cadmium tetrafluoroborate is fine tuning of the size of cadmium telluride nanomaterials.
Fluorine forms a great variety of chemical compounds, within which it always adopts an oxidation state of −1. With other atoms, fluorine forms either polar covalent bonds or ionic bonds. Most frequently, covalent bonds involving fluorine atoms are single bonds, although at least two examples of a higher order bond exist. Fluoride may act as a bridging ligand between two metals in some complex molecules. Molecules containing fluorine may also exhibit hydrogen bonding. Fluorine's chemistry includes inorganic compounds formed with hydrogen, metals, nonmetals, and even noble gases; as well as a diverse set of organic compounds. For many elements the highest known oxidation state can be achieved in a fluoride. For some elements this is achieved exclusively in a fluoride, for others exclusively in an oxide; and for still others the highest oxidation states of oxides and fluorides are always equal.
The hexafluoroarsenate anion is a chemical species with formula AsF−6. Hexafluoroarsenate is relatively inert, being the conjugate base of the notional superacid hexafluoroarsenic acid.