Calcium fluoride

From Wikipedia, the free encyclopedia - View original article

Calcium fluoride
Calcium fluoride.jpgFluorite-unit-cell-3D-ionic.png
Fluorid vápenatý.PNG
Identifiers
CAS number7789-75-5 YesY
PubChem24617
ChemSpider23019 YesY
UNIIO3B55K4YKI YesY
EC number232-188-7
ChEBICHEBI:35437 YesY
RTECS numberEW1760000
Jmol-3D imagesImage 1
Properties
Molecular formulaCaF2
Molar mass78.07 g mol−1
AppearanceWhite crystalline solid (single crystals are transparent)
Density3.18 g/cm3
Melting point1,418 °C; 2,584 °F; 1,691 K
Boiling point2,533 °C; 4,591 °F; 2,806 K
Solubility in water0.0015 g/100 mL (18 °C)
0.0016 g/100 mL (20 °C)
Solubility product, Ksp3.9 × 10−11 [1]
Solubilityinsoluble in acetone
slightly soluble in acid
Refractive index (nD)1.4338
Structure
Crystal structurecubic crystal system, cF12[2]
Space groupFm3m, #225
Coordination
geometry
Ca, 8, cubic
F, 4, tetrahedral
Hazards
EU IndexNot listed
R-phrasesR20, R22, R36, R37, R38
S-phrasesS26, S36
Main hazardsReacts with conc. sulfuric acid to enhance hydrofluoric acid
NFPA 704
NFPA 704.svg
0
0
0
Flash pointNon-flammable
LD504250 mg/kg (oral, rat)
Related compounds
Other anionsCalcium chloride
Calcium bromide
Calcium iodide
Other cationsBeryllium fluoride
Magnesium fluoride
Strontium fluoride
Barium fluoride
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references
 
Jump to: navigation, search
Calcium fluoride
Calcium fluoride.jpgFluorite-unit-cell-3D-ionic.png
Fluorid vápenatý.PNG
Identifiers
CAS number7789-75-5 YesY
PubChem24617
ChemSpider23019 YesY
UNIIO3B55K4YKI YesY
EC number232-188-7
ChEBICHEBI:35437 YesY
RTECS numberEW1760000
Jmol-3D imagesImage 1
Properties
Molecular formulaCaF2
Molar mass78.07 g mol−1
AppearanceWhite crystalline solid (single crystals are transparent)
Density3.18 g/cm3
Melting point1,418 °C; 2,584 °F; 1,691 K
Boiling point2,533 °C; 4,591 °F; 2,806 K
Solubility in water0.0015 g/100 mL (18 °C)
0.0016 g/100 mL (20 °C)
Solubility product, Ksp3.9 × 10−11 [1]
Solubilityinsoluble in acetone
slightly soluble in acid
Refractive index (nD)1.4338
Structure
Crystal structurecubic crystal system, cF12[2]
Space groupFm3m, #225
Coordination
geometry
Ca, 8, cubic
F, 4, tetrahedral
Hazards
EU IndexNot listed
R-phrasesR20, R22, R36, R37, R38
S-phrasesS26, S36
Main hazardsReacts with conc. sulfuric acid to enhance hydrofluoric acid
NFPA 704
NFPA 704.svg
0
0
0
Flash pointNon-flammable
LD504250 mg/kg (oral, rat)
Related compounds
Other anionsCalcium chloride
Calcium bromide
Calcium iodide
Other cationsBeryllium fluoride
Magnesium fluoride
Strontium fluoride
Barium fluoride
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Calcium fluoride is the inorganic compound with the formula CaF2. This ionic compound of calcium and fluorine occurs naturally as the mineral fluorite (also called fluorspar). It is the source of most of the world's fluorine. This insoluble solid adopts a cubic structure wherein calcium is coordinated to eight fluoride anions and each F ion is surrounded by four Ca2+ ions.[3] Although perfectly packed crystalline samples are colorless, the mineral is often deeply colored due to the presence of F-centers.

Chemical structure[edit]

The compound crystallizes in a cubic motif. Ca2+ centres are eight-coordinate, being centered in a "box" for eight F centres. Each F centre is coordinated to four Ca2+ centre.

The unit cell of fluorite's crystal structure

Preparation[edit]

The mineral fluorspar is abundant, widespread, and mainly of interest as a precursor to HF. Thus, little motivation exists for the industrial production of CaF2. High purity CaF2 is produced by treating calcium carbonate with hydrofluoric acid:[4]

CaCO3 + 2 HF → CaF2 + CO2 + H2O

Applications[edit]

Naturally occurring CaF2 is the principal source of hydrogen fluoride, a commodity chemical used to produce a wide range of materials. Hydrogen fluoride is liberated from the mineral by the action of concentrated sulfuric acid:[5]

CaF2(s) + H2SO4CaSO4(solid) + 2 HF(g)

Safety[edit]

CaF2 is classified "not dangerous." With regards to inhalation, the NIOSH-recommended concentration of fluorine-containing dusts is 2.5 mg/m3 in air.[4]

References[edit]

  1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  2. ^ X-ray Diffraction Investigations of CaF2 at High Pressure, L. Gerward, J. S. Olsen, S. Steenstrup, M. Malinowski, S. Åsbrink and A. Waskowska, Journal of Applied Crystallography (1992), 25, 578-581 doi:10.1107/S0021889892004096
  3. ^ G. L. Miessler and D. A. Tarr “Inorganic Chemistry” 3rd Ed, Pearson/Prentice Hall publisher, ISBN 0-13-035471-6.
  4. ^ a b Aigueperse, Jean; Paul Mollard, Didier Devilliers, Marius Chemla, Robert Faron, Renée Romano, Jean Pierre Cuer (2005), "Fluorine Compounds, Inorganic", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a11_307 
  5. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.

See also[edit]

Related materials[edit]

External links[edit]