Cobalt(II) carbonate

Cobalt(II) carbonate

Names
IUPAC name Cobalt(II) carbonate
Other names Cobaltous carbonate; cobalt(II) salt
Identifiers
CAS Number	513-79-1 N 12602-23-2 (cobalt carbonate hydroxide) N
PubChem	10565
Properties
Chemical formula	CoCO3
Appearance	red/ pink crystals (anhydrous) pink, violet, red crystalline powder (hexahydrate)
Density	4.13 g/cm3
Melting point	427 °C (801 °F; 700 K) [1] decomposes before melting to cobalt(II) oxide (anhydrous) 140 °C (284 °F; 413 K) decomposes (hexahydrate)
Solubility in water	negligible
Solubility product (Ksp)	1.0·10−10[2]
Solubility	soluble in acid negligible in alcohol, methyl acetate insoluble in ethanol
Refractive index (nD)	1.855
Structure
Crystal structure	Rhombohedral (anhydrous) Trigonal (hexahydrate)
Thermochemistry
Std molar entropy (So298)	79.9 J/mol·K[1]
Std enthalpy of formation (ΔfHo298)	−722.6 kJ/mol[1]
Gibbs free energy (ΔfG˚)	-651 kJ/mol[1]
Hazards
GHS pictograms	[3]
GHS signal word	Warning
GHS hazard statements	H302, H315, H317, H319, H335, H351[3]
GHS precautionary statements	P261, P280, P305+351+338[3]
EU classification (DSD)	Xn
R-phrases	R22, R36/37/38, R40, R43
S-phrases	S26, S36/37
NFPA 704	0 1 0
Lethal dose or concentration (LD, LC):
LD50 (Median dose)	640 mg/kg (oral, rats)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Cobalt(II) carbonate is the inorganic compound with the formula CoCO₃. This reddish paramagnetic solid is an intermediate in the hydrometallurgical purification of cobalt from its ores. It is an inorganic pigment, and a precursor to catalysts.^[4] Commercially available pale violet basic cobalt carbonate, with the formula CoCO₃(Co(OH)_x(H₂O)_y (CAS 12069-68-0).^[5]

Preparation and properties

It is prepared by heating cobaltous sulfate with a solution of sodium bicarbonate.

Heating the carbonate, i.e. calcining, proceeds in the usual way:

3 CoCO₃ + 1/2 O₂ → Co₃O₄ + 3 CO₂

The resulting Co₃O₄ converts reversibly to CoO at high temperatures.^[6] Like most transition metal carbonates, cobalt carbonate is insoluble in water but is readily attacked by mineral acids:

CoCO₃ + 2 HCl + 5 H₂O → [Co(H₂O)₆]Cl₂ + CO₂

Uses

Cobalt carbonate is a precursor to cobalt carbonyl and various cobalt salts. It is a component of dietary supplements since cobalt is an essential element. It is a precursor to blue pottery glazes, famously in the case of Delftware.

Safety

The compound is harmful if swallowed, and irritating to eyes and skin.

References

External links

Wikimedia Commons has media related to Cobalt(II) carbonate.