Cadmium fluoride

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Cadmium fluoride
Fluorite-unit-cell-3D-ionic.png
Identifiers
CAS number 7790-79-6 YesY
ChemSpider 23036 YesY
EC number 232-222-0
Jmol-3D images Image 1
Properties
Molecular formula 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)
Solubility in water 4.35 g/100 mL
Solubility soluble in acid
insoluble in ethanol alcohol and liquid ammonia
Structure
Crystal structure Fluorite (cubic), cF12
Space group Fm3m, No. 225
Hazards
EU Index 048-006-00-2
EU classification Carc. Cat. 2
Muta. Cat. 2
Repr. Cat. 2
Highly toxic (T+)
Dangerous for the environment (N)
R-phrases R45, R46, R60, R61, R25, R26, R48/23/25, R50/53
S-phrases S53, S45, S60, S61
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 noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

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.[1] 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.[2] [3]

Preparation[edit]

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.[4]

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.[5]

Uses[edit]

Electronic Conductor[edit]

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.[6]

Safety[edit]

Cadmium fluoride, like all cadmium compounds, is toxic and should be used with care. Fluoride is mildly toxic by comparison.

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. [7]

See also[edit]

References[edit]

  1. ^ "Cadmium Fluoride". Retrieved 2009-06-06. 
  2. ^ Rudzitis, Edgars; Feder, Harold; Hubbard (November 1963). "Fluorine Bomb Calorimetry. VII. The Heat of Formation of Cadmium Difluoride.". Journal of Physical Chemistry. doi:10.1021/j100805a031.  |first3= missing |last3= in Authors list (help)
  3. ^ Besenbruch, G.; Kana'an, A. S.; Margrave, J. L. (March 3, 1965). "Knudson and Langmuir Measurements of the Sublimation Pressure of Cadmium (II) Fluoride". Journal of Physical Chemistry. doi:10.1021/j100893a505. 
  4. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  5. ^ Haendler, Helmut; Bernard, Walter (November 1951). "The Reaction of Fluorine with Cadmium and Some of its Binary Compounds. The Crystal Structure, Density and Melting Points of Cadmium Fluoride.". Journal of the American Chemical Society. doi:10.1021/ja01155a064. 
  6. ^ Weller, Paul (June 1, 1965). "Electrical and Optical Properties of Rare Earth Doped Cadmium Fluoride Single Crystals". Journal of Inorganic Chemistry. doi:10.1021/ic50033a004. 
  7. ^ "Cadmium Fluoride [CdF2]". MSDS Solutions Center. Advance Research Chemicals Inc. / A.R.C. 2011-04-01. Retrieved 2014-12-12. 

External links[edit]