Definition and Uses :
Cobalt (II) chloride is an inorganic compound of cobalt and chlorine with the formula CoCl 2 . It is usually given as the hexahydrate CoCl 2 6H 2 O, one of the most commonly used cobalt compounds in the laboratory.
The hexahydrate is purple, whereas the anhydrous form is sky blue. Because of the ease of hydration/dehydration reaction and the resulting color change, cobalt chloride is used as an indicator for water, which is desiccating.
Niche uses of cobalt chloride also include roles in organic synthesis and electroplating cobalt metal objects.
Cobalt chloride is classified as a substance of very high concern by the European Chemicals Agency, as it is a suspected carcinogen.
Uses
Invisible ink
Cobalt chloride is a known chemical stimulant of hypoxia-like responses such as erythropoiesis.