3D model (JSmol)
|Molar mass||96.93 g/mol|
|Appearance||Red crystalline solid|
|Density||4.46 g/cm3 (anhydrous) |
2.22 g/cm3 (tetrahydrate)
|Melting point||1,217 °C (2,223 °F; 1,490 K)|
|Boiling point||1,400 °C (2,550 °F; 1,670 K)|
|1.4 g/100 mL (25 °C)|
|Solubility||soluble in HF |
insoluble in alcohol, ether, benzene
|tetragonal (a,hydrous) |
|Other anions||cobalt(II) oxide, cobalt(II) chloride|
|Other cations||iron(II) fluoride, nickel(II) fluoride|
|Related compounds||cobalt trifluoride|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Properties[change | change source]
It is a reddish crystalline solid. It only dissolves a little in water. The hydrate (type with water molecules attached) can dissolve in water. It can dissolve in acid. It can react with hydrogen at 300 °C (572 °F) to make cobalt and hydrogen fluoride.
Preparation[change | change source]
It can be made by reacting anhydrous (without any water molecules attached) cobalt(II) oxide or cobalt(II) chloride with a stream of hydrogen fluoride. This reaction makes the anhydrous form. The hydrated (with water molecules attached) form is made by reacting any cobalt(II) compound with hydrofluoric acid. When fluorine is reacted with cobalt at a high temperature, it makes both cobalt(II) fluoride and cobalt(III) fluoride.