Cadmium chloride

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Cadmium chloride
Ball-and-stick model of cadmium chloride Cadmium chloride in polyhedron shape
Cadmium chloride hemipentahydrate
Identifiers
CAS number 10108-64-2 YesY, 34330-64-8 (monohydrate)
PubChem 24947
ChemSpider 23035 YesY
UNII J6K4F9V3BA YesY
EC number 233-296-7
UN number 2570
ChEBI CHEBI:35456 YesY
RTECS number EV0175000
Jmol-3D images Image 1
Properties
Molecular formula CdCl2
Molar mass 183.32 g mol−1
Appearance White solid, hygroscopic
Odor Odorless
Density 4.047 g/cm3 (anhydrous)[1]
3.327 g/cm3 (pentahydrate)[2]
Melting point 568 °C (1,054 °F; 841 K)
at 760 mmHg[2]
Boiling point 964 °C (1,767 °F; 1,237 K)
at 760 mmHg[2]
Solubility in water Hemipentahydrate:
79.5 g/100 mL (−10 °C)
90 g/100 mL (0 °C)
Monohydrate:
119.6 g/100 mL (25 °C)[2]
134.3 g/100 mL (40 °C)
134.2 g/100 mL (60 °C)
147 g/100 mL (100 °C)[3]
Solubility Soluble in alcohol, selenium(IV) oxychloride, benzonitrile
Insoluble in ether, acetone[1]
Solubility in pyridine 4.6 g/kg (0 °C)
7.9 g/kg (4 °C)
8.1 g/kg (15 °C)
6.7 g/kg (30 °C)
5 g/kg (100 °C)[1]
Solubility in ethanol 1.3 g/100 g (10 °C)
1.48 g/100 g (20 °C)
1.91 g/100 g (40 °C)
2.53 g/100 g (70 °C)[1]
Solubility in dimethyl sulfoxide 18 g/100 g (25 °C)[1]
Vapor pressure 0.01 kPa (471 °C)
0.1 kPa (541 °C)[2]
Magnetic susceptibility −6.87·10−5 cm3/mol[2]
Viscosity 2.31 cP (597 °C)
1.87 cP (687 °C)[1]
Structure
Crystal structure Rhombohedral, hR9 (anhydrous)[4]
Monoclinic (hemipentahydrate)[3]
Space group R3m, No. 166 (anhydrous)[4]
Point group 3 2/m (anhydrous)[4]
Lattice constant a = 3.846 Å, c = 17.479 Å (anhydrous)[4]
Lattice constant α = 90°, β = 90°, γ = 120°
Thermochemistry
Specific
heat capacity
C
74.7 J/mol·K[2]
Std molar
entropy
So298
115.3 J/mol·K[2]
Std enthalpy of
formation
ΔfHo298
−391.5 kJ/mol[2]
Gibbs free energy ΔG −343.9 kJ/mol[2]
Hazards
MSDS External MSDS
GHS pictograms The skull-and-crossbones pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)The health hazard pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)The environment pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)[5]
GHS signal word Danger
GHS hazard statements H301, H330, H340, H350, H360, H372, H410[5]
GHS precautionary statements P210, P260, P273, P284, P301+310, P310[5]
EU Index 048-008-00-3
EU classification Very Toxic T+ Dangerous for the Environment (Nature) N
Carc. Cat. 2
Muta. Cat. 2
Repr. Cat. 2
R-phrases R45, R46, R60, R61, R25, R26, R48/23/25, R50/53
S-phrases S53, S45, S60, S61
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
LD50 94 mg/kg (rats, oral)[1]
Related compounds
Other anions Cadmium fluoride
Cadmium bromide
Cadmium iodide
Other cations Zinc chloride
Mercury(II) chloride
Calcium chloride
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 chloride is a white crystalline compound of cadmium and chlorine, with the formula CdCl2. It is a hygroscopic solid that is highly soluble in water and slightly soluble in alcohol. Although it is considered to be ionic, it has considerable covalent character to its bonding. The crystal structure of cadmium chloride (described below), composed of two-dimensional layers of ions, is a reference for describing other crystal structures. Also known are CdCl2.H2O and CdCl2.5H2O.[2]

Structure[edit]

Cadmium chloride forms crystals with rhombohedral symmetry. Cadmium iodide, CdI2, has a very similar crystal structure to CdCl2. The individual layers in the two structures are identical, but in CdCl2 the chloride ions are arranged in a CCP lattice, whereas in CdI2 the iodide ions are arranged in an HCP lattice.[6][7]

Chemical properties[edit]

Cadmium chloride dissolves well in water and other polar solvents. In water, its high solubility is due in part to formation of complex ions such as [CdCl4]2−. Because of this behavior, CdCl2 is a mild Lewis acid).[6]

CdCl2 + 2 Cl → [CdCl4]2−

With large cations, it is possible to isolate the trigonal bipyramidal [CdCl5]3− ion.

Preparation[edit]

Anhydrous cadmium chloride can be prepared by the action of anhydrous chlorine or hydrogen chloride gas on heated cadmium metal.

Cd + 2 HCl → CdCl2 + H2

Hydrochloric acid may be used to make hydrated CdCl2 from the metal, or from cadmium oxide or cadmium carbonate.

Uses[edit]

Cadmium chloride is used for the preparation of cadmium sulfide, used as "Cadmium Yellow", a brilliant-yellow stable inorganic pigment.

CdCl
2
+ H
2
S
CdS + 2 HCl

In the laboratory, anhydrous CdCl2 can be used for the preparation of organocadmium compounds of the type R2Cd, where R is an aryl or a primary alkyl. These were once used in the synthesis of ketones from acyl chlorides:[8]

CdCl
2
+ 2 RMgX → R
2
Cd
+ MgCl
2
+ MgX
2
R
2
Cd
+ R'COCl → R'COR + CdCl
2

Such reagents have largely been supplanted by organocopper compounds, which are much less toxic.

Cadmium chloride is also used for photocopying, dyeing and electroplating.

References[edit]

  1. ^ a b c d e f g Anatolievich, Kiper Ruslan. "cadmium chloride". http://chemister.ru. Retrieved 2014-06-25. 
  2. ^ a b c d e f g h i j k Lide, David R., ed. (2009). CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4200-9084-0. 
  3. ^ a b Seidell, Atherton; Linke, William F. (1919). Solubilities of Inorganic and Organic Compounds (2nd ed.). New York: D. Van Nostrand Company. p. 169. 
  4. ^ a b c d "Cadmium Chloride - CdCl2". http://wwwchem.uwimona.edu.jm. Mona, Jamaica: The University of the West Indies. Retrieved 2014-06-25. 
  5. ^ a b c Sigma-Aldrich Co., Cadmium chloride. Retrieved on 2014-05-23.
  6. ^ a b N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.
  7. ^ A. F. Wells, Structural Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, UK, 1984.
  8. ^ J. March, Advanced Organic Chemistry, 4th ed., p. 723, Wiley, New York, 1992.

External links[edit]