| Preparation | Cobalt(II) fluoride is prepared by heating anhydrous cobalt(II) chloride or oxide in a stream of hydrogen fluoride:
CoCl2 + 2HF → CoF2 + 2HCl
CoO + 2HF → CoF2 + 2H2O
Also, cobalt(II) fluoride can be prepared as a tetrahydrate, CoF2•4H2O by dissolving cobalt(II) hydroxide in hydrofluoric acid. The tetrahydrate is then dehydrated to anhydrous fluoride. Elemental fluorine combines with cobalt at 450°C forming mixtures of cobalt(II)–and cobalt(III) fluorides.
|
| Chemical Properties | Rose-red crystals or powder. Soluble in cold
water and hydrofluoric acid. Decomposes in hot
water. Ammine complexes can be prepared from
the hydrate. |
| Physical properties | Red tetragonal crystal; density 4.46 g/cm3; melts at 1,127°C; vaporizes around 1,400°C; sparingly soluble in water; soluble in warm mineral acids; decomposes in boiling water. Tetrahydrate is red orthogonal crystal; density 2.22 g/cm3; decomposes on heating; soluble in water; di- and trihydrates are soluble in water. |
| Uses | Cobalt(II) fluoride can be used as a catalyst to alloy metals. It is also used for optical deposition, of which it tremendously improves optical quality. The compound may be used in dental care. |
| Uses | Catalyst for organic reactions. |
| General Description | Violet to red solid. Sinks and mixes slowly with water. |
| Reactivity Profile | Cobalt(II) fluoride is a toxic, light brown crystalline material, when exposed to water Cobalt(II) fluoride forms highly corrosive hydrofluoric acid. When heated to decomposition Cobalt(II) fluoride emits toxic fumes of metallic cobalt and fluorides [Lewis, 3rd ed., 1993, p. 344]. |
| Hazard | Highly toxic. |
| Health Hazard | INHALATION: Inhalation of dust may cause pulmonary symptoms. EYES: Irritation. SKIN: Skin rashes, dermatitis. INGESTION: Nausea and vomiting caused by local irritation.
LD50 oral (rat): 150 mg/kg
|
| Safety Profile | Poison by ingestion.
When heated to decomposition it emits
toxic fumes of Co and F-. |
