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
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.
Uses
It is used as a catalyst. It can be used as a source of the fluoride ion in dentist care. It is used in lenses.