Zinc carbonate

Structural formula
General
Surname	Zinc carbonate
other names	Smithsonite Zinc spar ZINC CARBONATE ( INCI )
Molecular formula	ZnCO 3
Brief description	colorless to yellowish, odorless solid
External identifiers / databases
CAS number 3486-35-9 EC number 222-477-6 ECHA InfoCard 100.020.435 PubChem 19005 Wikidata Q204661
properties
Molar mass	125.42 g mol −1
Physical state	firmly
density	4.43 g cm −3
Melting point	≈ 300 ° C (decomposition)
solubility	almost insoluble in water (10 mg l −1 at 15 ° C)
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 410 P: 273-391-501
Thermodynamic properties
ΔH f 0	−812.8 kJ / mol
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

In chemistry, zinc carbonate is a zinc salt of carbonic acid ( carbonate ).

Occurrence

Zinc carbonate occurs naturally as smithsonite ( zinc spar ).

Extraction and presentation

Zinc carbonate with the chemical composition ZnCO ₃ is formed as a white precipitate when the zinc salt and soda solution are combined.

It is also formed when zinc salts react with potassium hydrogen carbonate .

${\displaystyle \mathrm {ZnSO_{4}+4\ KHCO_{3}\longrightarrow ZnCO_{3}+\ K_{2}SO_{4}+\ K_{2}CO_{3}+2\ CO_{2}+\ 2\ H_{2}O} }$

${\displaystyle \mathrm {ZnCl_{2}+4\ KHCO_{3}+\ x\ CO2\longrightarrow ZnCO_{3}+\ 2\ KCl+\ K_{2}CO_{3}+\ (x+2)CO_{2}+\ 2\ H_{2}O} }$

properties

It is a white, acid- soluble powder that can be converted into zinc oxide when glowing (burning with separation of carbon dioxide ):

${\displaystyle \mathrm {ZnCO_{3}\longrightarrow \ ZnO+CO_{2}\uparrow } }$

In strong alkalis, zinc carbonate complex can be dissolved as colorless tetrahydroxozincate ( complex formation reaction ). It crystallizes in the trigonal crystal system and usually develops rhombohedral crystals in predominantly blue or green color (colorless, white, light yellow or brown crystals are also known). From a chemical point of view, the properties of zinc carbonate are similar to those of lime ( calcium carbonate ), however, unlike calcium compounds, zinc-II salt solutions form sulfide precipitates, but no precipitates when sulfuric acid is added . Aqueous suspensions of zinc carbonate have an alkaline reaction.

use

Zinc carbonate is used as a pigment and is found in pharmaceutical preparations. It is also used for the production of zinc oxide pigments, for the absorption of hydrogen sulfide when flushing deep boreholes and in textile dyeing / textile printing. It is also used as an activator for the sulfur and thiuram vulcanization of translucent and semi-transparent rubber articles, as a vulcanizing agent in carboxylated rubbers and as an activator in latex articles.

The protection against corrosion that hot-dip galvanizing offers is based on the formation of protective cover layers that are created over time on the surface of hot-dip galvanized steel parts as a result of the weather. These top layers consist mainly of zinc carbonate.

See also

• Zinc hydroxide carbonate (basic zinc carbonate), [ZnCO ₃ ] ₂ · [Zn (OH) ₂ ] ₃ , CAS number: 5263-02-5
• Dizinc Carbonate Zn ₂ CO ₃

Individual evidence

1. ↑ entry to ZINC CARBONATE in CosIng database of the European Commission, accessed on 11 March 2020th
2. ↑ ^{a b c d e} Entry on zinc carbonate in the GESTIS substance database of the IFA , accessed on January 9, 2019(JavaScript required) .
3. ↑ H. Effenberger, K. Mereiter, J. Zemann: Crystal structure refinements of magnesite, calcite, rhodochrosite, siderite, smithonite, and dolomite, with discussion of some aspects of the stereochemistry of calcite type carbonates . In: Journal of Crystallography . tape 156 , no. 3-4 , 1981, pp. 233-243 , doi : 10.1524 / zkri.1981.156.3-4.233 .
4. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-20.
5. ↑ Georg Brauer (Ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume II, Ferdinand Enke, Stuttgart 1978, ISBN 3-432-87813-3 , p. 1035.
6. ↑ brueggemann.com: zinc carbonate .
7. ↑ Worksheets for hot-dip galvanizing: Storage and transport of hot-dip galvanized steel .