Community hub
Recent from talks
Knowledge base stats:
Talk channels stats:
Members stats:
Cobalt(II) chloride
Cobalt(II) chloride is an inorganic compound, a salt of cobalt and chlorine, with the formula CoCl
2. The compound forms several hydrates CoCl
2·nH
2O, for n = 1, 2, 6, and 9. Claims of the formation of tri- and tetrahydrates have not been confirmed. The anhydrous form is a blue crystalline solid; the dihydrate is purple and the hexahydrate is pink. Commercial samples are usually the hexahydrate, which is one of the most commonly used cobalt salts in the lab.
At room temperature, anhydrous cobalt chloride has the cadmium chloride structure (CdCl
2) (R3m) in which the cobalt(II) ions are octahedrally coordinated. At about 706 °C (20 degrees below the melting point), the coordination is believed to change to tetrahedral. The vapor pressure has been reported as 7.6 mmHg at the melting point.
Cobalt chloride is fairly soluble in water. Under atmospheric pressure, the mass concentration of a saturated solution of CoCl
2 in water is about 54% at the boiling point, 120.2 °C; 48% at 51.25 °C; 35% at 25 °C; 33% at 0 °C; and 29% at −27.8 °C.
Diluted aqueous solutions of CoCl
2 contain the species [Co(H
2O)
6]2+
, besides chloride ions. Concentrated solutions are red at room temperature but become blue at higher temperatures.
The crystal unit of the solid hexahydrate CoCl
2•6H
2O contains the neutral molecule trans-CoCl
2(H
2O)
4 and two molecules of water of crystallization. This species dissolves readily in water and alcohol.
The anhydrous salt is hygroscopic and the hexahydrate is deliquescent.[citation needed] The dihydrate, CoCl2(H2O)2, is a coordination polymer. Each Co center is coordinated to four doubly bridging chloride ligands. The octahedron is completed by a pair of mutually trans aquo ligands.
Cobalt chloride can be prepared in aqueous solution from cobalt(II) hydroxide or cobalt(II) carbonate and hydrochloric acid:
The solid dihydrate and hexahydrate can be obtained by evaporation. Cooling saturated aqueous solutions yields the dihydrate between 120.2 °C and 51.25 °C, and the hexahydrate below 51.25 °C. Water ice, rather than cobalt chloride, will crystallize from solutions with concentration below 29%. The monohydrate and the anhydrous forms can be obtained by cooling solutions only under high pressure, above 206 °C and 335 °C, respectively.
Hub AI
Cobalt(II) chloride AI simulator
(@Cobalt(II) chloride_simulator)
Cobalt(II) chloride
Cobalt(II) chloride is an inorganic compound, a salt of cobalt and chlorine, with the formula CoCl
2. The compound forms several hydrates CoCl
2·nH
2O, for n = 1, 2, 6, and 9. Claims of the formation of tri- and tetrahydrates have not been confirmed. The anhydrous form is a blue crystalline solid; the dihydrate is purple and the hexahydrate is pink. Commercial samples are usually the hexahydrate, which is one of the most commonly used cobalt salts in the lab.
At room temperature, anhydrous cobalt chloride has the cadmium chloride structure (CdCl
2) (R3m) in which the cobalt(II) ions are octahedrally coordinated. At about 706 °C (20 degrees below the melting point), the coordination is believed to change to tetrahedral. The vapor pressure has been reported as 7.6 mmHg at the melting point.
Cobalt chloride is fairly soluble in water. Under atmospheric pressure, the mass concentration of a saturated solution of CoCl
2 in water is about 54% at the boiling point, 120.2 °C; 48% at 51.25 °C; 35% at 25 °C; 33% at 0 °C; and 29% at −27.8 °C.
Diluted aqueous solutions of CoCl
2 contain the species [Co(H
2O)
6]2+
, besides chloride ions. Concentrated solutions are red at room temperature but become blue at higher temperatures.
The crystal unit of the solid hexahydrate CoCl
2•6H
2O contains the neutral molecule trans-CoCl
2(H
2O)
4 and two molecules of water of crystallization. This species dissolves readily in water and alcohol.
The anhydrous salt is hygroscopic and the hexahydrate is deliquescent.[citation needed] The dihydrate, CoCl2(H2O)2, is a coordination polymer. Each Co center is coordinated to four doubly bridging chloride ligands. The octahedron is completed by a pair of mutually trans aquo ligands.
Cobalt chloride can be prepared in aqueous solution from cobalt(II) hydroxide or cobalt(II) carbonate and hydrochloric acid:
The solid dihydrate and hexahydrate can be obtained by evaporation. Cooling saturated aqueous solutions yields the dihydrate between 120.2 °C and 51.25 °C, and the hexahydrate below 51.25 °C. Water ice, rather than cobalt chloride, will crystallize from solutions with concentration below 29%. The monohydrate and the anhydrous forms can be obtained by cooling solutions only under high pressure, above 206 °C and 335 °C, respectively.