Manganese(II) carbonate

Manganese carbonate is a compound with the chemical formula MnCO₃. Manganese carbonate occurs naturally as the mineral rhodochrosite but it is typically produced industrially. It is a pale pink, water-insoluble solid. Approximately 20,000 metric tonnes were produced in 2005.^[3]

Manganese(II) carbonate

Names
IUPAC name Manganese(II) carbonate
Identifiers
CAS Number	598-62-9 Y
3D model (JSmol)	Interactive image
ChemSpider	11233 Y
ECHA InfoCard	100.009.040
EC Number	209-942-9
PubChem CID	11726
UNII	9ZV57512ZM Y
CompTox Dashboard (EPA)	DTXSID1042108
InChI InChI=1S/CH2O3.Mn/c2-1(3)4;/h(H2,2,3,4);/q;+2/p-2 Y Key: XMWCXZJXESXBBY-UHFFFAOYSA-L Y InChI=1/CH2O3.Mn/c2-1(3)4;/h(H2,2,3,4);/q;+2/p-2 Key: XMWCXZJXESXBBY-NUQVWONBAJ
SMILES [Mn+2].[O-]C([O-])=O
Properties
Chemical formula	MnCO3
Molar mass	114.95 g mol−1
Appearance	White to faint pink solid
Density	3.12 g/cm3
Melting point	200–300 °C (392–572 °F; 473–573 K) decomposes[1][2]
Solubility in water	negligible
Solubility product (Ksp)	2.24 x 10−11
Solubility	soluble in dilute acid, CO2 insoluble in alcohol, ammonia
Magnetic susceptibility (χ)	+11,400·10−6 cm3/mol
Refractive index (nD)	1.597 (20 °C, 589 nm)
Structure
Crystal structure	hexagonal-rhombohedral
Thermochemistry
Heat capacity (C)	94.8 J/mol·K[2]
Std molar entropy (S⦵298)	109.5 J/mol·K[2]
Std enthalpy of formation (ΔfH⦵298)	-881.7 kJ/mol[2]
Gibbs free energy (ΔfG⦵)	-811.4 kJ/mol[2]
Hazards
Flash point	Non-flammable
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Structure and production

MnCO₃ adopts a structure like calcite, consisting of manganese(II) ions in an octahedral coordination geometry.^[4]

Treatment of aqueous solutions of manganese(II) nitrate with ammonia and carbon dioxide leads to precipitation of this faintly pink solid. The side product, ammonium nitrate is used as fertilizer.

Pink rhodochrosite, the mineral form of MnCO₃, is of practical value as well as sought by collectors.

Reactions and uses

The carbonate is insoluble in water but, like most carbonates, hydrolyses upon treatment with acids to give water-soluble salts.

Manganese carbonate decomposes with release of carbon dioxide, i.e. calcining, at 200 °C to give MnO_1.88:

MnCO₃ + 0.44 O₂ → MnO_1.8 + CO₂

This method is sometimes employed in the production of manganese dioxide, which is used in dry-cell batteries and for ferrites.^[3]

Manganese carbonate is widely used as an additive to plant fertilizers to cure manganese deficient crops. It is also used in health foods, in ceramics as a glaze colorant and flux, and in concrete stains.^[5]

It is used in medicine as a hematinic.

Toxicity

Manganese poisoning, also known as manganism, may be caused by long-term exposure to manganese dust or fumes.

See also

• Manganese deficiency (medicine)

References

1. Sigma-Aldrich Co., Manganese(II) carbonate. Retrieved on 2014-05-06.
2. "Manganese(II) carbonate".
3. Arno H. Reidies (2007). "Manganese Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a16_123. ISBN 978-3527306732.
4. Pertlik, F. (1986). "Structures of hydrothermally synthesized cobalt(II) carbonate and nickel(II) carbonate". Acta Crystallographica Section C. 42: 4–5. doi:10.1107/S0108270186097524.
5. "How To Stain Concrete with Manganese"