COBALT CYANIDE Property

Density 

d425 1.872

solubility 

insoluble in H2O

form 

blue hygroscopic crystals

color 

blue hygroscopic crystals, crystalline

EPA Substance Registry System

Cobalt cyanide (Co(CN)2) (542-84-7)

Safety

Hazard Codes 

T+,N

Risk Statements 

26/27/28-32-50/53

Safety Statements 

7-28-29-45-60-61

RIDADR 

UN 1588 6.1/PG 2

WGK Germany 

2

HazardClass 

6.1(a)

PackingGroup 

II

Hazard and Precautionary Statements (GHS)

COBALT CYANIDE Chemical Properties,Usage,Production

Physical properties

The anhydrous form is a deep-blue powder; hygroscopic; density 1.872 g/cm³; melts at 280°C; insoluble in water. The dihydrate is pink to reddish brown powder or needles; insoluble in water and acids; soluble in sodium or potassium cyanide solutions, ammonium hydroxide, and hydrochloric acid.

Uses

The compound has limited commercial applications. It is used as a catalyst and in the preparation of cyanide complexes.

Preparation

The trihydrate salt is obtained as a reddish brown precipitate by adding potasium cyanide to a cobalt salt solution:
CoCl₂ + KCN + 3H₂O → Co(CN)₂?3H₂O + 2KCl
This on dehydration yields anhydrous Co(CN)₂. The Co(CN)₂?3H₂O precipitate formed above redissolves when excess KCN is added, forming a red solution of potassium cobalt(II) cyanide, K₄Co(CN)₆. Stoichiomtric amount of KCN should, therefore, be used in the preparation of cobalt(II) cyanide.

Hazard

The compound is highly toxic by ingestion and possibly through other routes of exposure.