Holmium(III) chloride is the inorganic compound with the formula HoCl3. It is a common salt but is mainly used in research. It can be used to produce pure holmium. It exhibits the same color-changing behavior seen in holmium oxide, being a yellow in natural lighting and a bright pink color in fluorescent lighting.
Preparation The most commonly used method to obtain holmium(III) chloride involves heating a mixture of holmium(III) oxide and ammonium chloride at 200-250 °C:Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY.
Ho2O3 + 6 NH4Cl → 2 HoCl3 + 6 NH3 + 2 H2O
The hexahydrate of holmium(III) chloride can be obtained by reaction between holmium and hydrochloric acid:
2 Ho + 6 HCl → 2 HoCl3 + 3 H2
It can also be prepared by the direct reaction between holmium and chlorine:Webelements: Holmium
2 Ho + 3 Cl2 → 2 HoCl3
Properties Holmium(III) chloride and its hexahydrate are light yellow solids in daylight that are soluble in water. The hexahydrate starts to release water of crystallization at 64 °C. Holmium(III) chloride has a monoclinic crystal structure analogous to that of aluminum(III) chloride. In the solid state it has the YCl3 layer structure.Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford.
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