|Jmol-3D images||Image 1|
|Molecular formula||ErCl3 (anhydrous)
|Molar mass||273.62 g/mol (anhydrous)
381.71 g/mol (hexahydrate)
|Appearance||violet hygroscopic monoclinic crystals (anhydrous)
pink hygroscopic crystals (hexahydrate)
|Density||4.1 g/cm3 (anhydrous)|
776 °C (anhydrous)
|Solubility in water||soluble in water (anhydrous)
slightly soluble in ethanol (hexahydrate)
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
It is also found as a pink crystalline hexahydrate, CAS number [10025-75-9]. It has the interesting property that the pink colour is much more intense under the light from a fluorescent lamp, as may be seen from the picture.
Anhydrous erbium(III) chloride is formed from the hexahydrate by heating under a strongly chlorinating atmosphere, such as chlorine or hydrogen chloride; otherwise erbium oxide chloride, ErOCl, is formed. An alternative preparation is to react the readily available Er2O3 with excess NH4Cl to make the intermediate salt (NH4)3ErCl6 plus both ammonia and water. This salt is stable with respect to hydrolysis and can be thermally decomposed under vacuum to yield anhydrous erbium(III) chloride with loss of ammonia and gaseous HCl.
It reacts with alkalis to form erbium(III) hydroxide:
ErCl3 + 3 XOH → Er(OH)3 + 3 XCl
Structural data 
Erbium(III) chloride hexahydrate also forms monoclinic crystals with the point group of P2/n (P2/c) - C42h. The erbium is octa-coordinated to form [Er(H2O)6Cl2]+ ions with the isolated Cl− completing the structure.
Optical properties 
Catalytic properties 
- Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, FL: CRC Press. pp. 4–57. ISBN 0-8493-0594-2
- Tempelton DH, Carter GF (1954). "The Crystal Structure of Yttrium Trichloride and Similar Compounds". J Phys Chem 58 (11): 940–943. doi:10.1021/j150521a002.
- Graebner EJ, Conrad GH Duliere SF (1966). Crystallographic data for solvated rare earth chlorides 21. p. 1021.
- Maeda Y, Akidzuki Y, Yamada T (1998). "All-optical liquid device derived from negative nonlinear absorption effect in an erbium chloride solution". Applied Physics Letters 73 (17): 2411–2413. doi:10.1063/1.122450.
- CSIRO PUBLISHING - Australian Journal of Chemistry