 | |
| Names | |
|---|---|
| IUPAC name Cadmium fluoride | |
| Other names Cadmium(II) fluoride, Cadmium difluoride | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider |
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| ECHA InfoCard | 100.029.293 |
| EC Number |
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| UNII | |
| |
| |
| 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 inacid insoluble inethanol alcohol and liquidammonia |
| −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 | |
Otheranions | Cadmium chloride, Cadmium bromide Cadmium iodide |
Othercations | 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 theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Cadmium fluoride (CdF2) is a mostly water-insoluble source ofcadmium used in oxygen-sensitive applications, such as the production of metallic alloys.
Cadmium fluoride is prepared by the reaction of gaseous fluorine orhydrogen fluoride with cadmium metal or itssalts, such as thechloride,oxide, orsulfate.
It may also be obtained by dissolvingcadmium carbonate in 40%hydrofluoric acid solution, evaporating the solution and drying in a vacuum at 150 °C.
Another method of preparing it is to mixcadmium chloride andammonium fluoride solutions, followed bycrystallization. The insoluble cadmium fluoride is filtered from solution.[3]
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.[4]
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.[5] The heat of sublimation was determined to be 76 kcal. mole−1[6]
In extremely low concentrations (ppm), this and other fluoride compounds are used in limited medical treatment protocols.[citation needed]
Fluoride compounds also have significant uses in syntheticorganic chemistry.[7]
CdF2 can be transformed into an electronic conductor when doped with certain rare earth elements, includingyttrium; 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 withinterstitial 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 ascongestion, fluorosis, and evenpulmonary edema in extreme cases. Cadmium fluoride also has the same potential hazards caused by cadmium and fluoride.[9]
