Barium chromate

Structural formula
General
Surname	Barium chromate
other names	Barite yellow; Ultramarine yellow; Permanent yellow; CI 77103; CI Pigment Yellow 31;
Molecular formula	BaCrO 4
Brief description	yellow odorless solid
External identifiers / databases
EC number	233-660-5
ECHA InfoCard	100.030.587
PubChem	25136
ChemSpider	23481
Wikidata	Q206690
properties
Molar mass	253.32 g mol −1
Physical state	firmly
density	4.5 g cm −3
Melting point	210 ° C
solubility	very heavy in water (0.34 g l −1 at 20 ° C)
safety instructions
H and P phrases	H: 272-302 + 332
	P: 210-220-221-261-301 + 312 + 330-370 + 378
MAK	0.5 mg m −3 barium
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Barium chromate is a barium salt of chromic acid . It has the formula BaCrO ₄ and belongs to the chromate group .

Extraction / representation

The yellow barium chromate is obtained by precipitating barium ions with chromate ions from a slightly acidic solution.

{\ displaystyle \ mathrm {Ba _ {(aq)} ^ {2 +} + CrO_ {4} ^ {2 -} \ longrightarrow BaCrO_ {4} \ downarrow (yellow)}}

properties

Barium chromate is a yellow solid that is practically insoluble in water and therefore, unlike most other chromates, is not acutely toxic, so that the safety instructions for soluble chromates for barium chromate only apply to a limited extent. On the other hand, poorly soluble chromate particles are particularly carcinogenic in the case of inhalation exposure, and barium chromate has a clastogenic effect that goes beyond the classic, genotoxic effects of soluble chromium (VI) compounds. Like all chromates, barium chromate has an oxidizing effect (particularly strong under acidic conditions). It shows the green flame color typical of barium .

When heated with barium carbonate , the hexavalent chromium is reduced to the pentavalent one, barium chromate (V) Ba ₃ (CrO ₄ ) _{2 is formed} .

{\ displaystyle \ mathrm {4 \ BaCrO_ {4} +2 \ BaCO_ {3} \ {\ xrightarrow {\ 800 ^ {o} C \}} \ 2 \ Ba_ {3} (CrO_ {4}) _ {2 } +2 \ CO_ {2} + O_ {2}}}

use

Barium chromate is used as a pigment in the glass and paint industry . In pyrotechnics , barium chromate is used as an oxidizing agent and for green coloring.

Individual evidence

↑ Entry on barium chromate. In: Römpp Online . Georg Thieme Verlag, accessed on June 27, 2014.
↑ ^a ^b ^c ^d ^e Entry on barium chromate in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .
↑ ^a ^b data sheet barium chromate at AlfaAesar, accessed on March 14, 2010 ( PDF )(JavaScript required) .
↑ SS Wise, AL Holmes, Q. Qin, H. Xie, SP Katsifis, WD Thompson, JP Wise: Comparative genotoxicity and cytotoxicity of four hexavalent chromium compounds in human bronchial cells. In: Chemical research in toxicology. Volume 23, number 2, February 2010, pp. 365-372, doi : 10.1021 / tx900363j , PMID 20000473 , PMC 2822000 (free full text).
^ KA Wilhelmi, O. Jonsson: X-Ray Studies on Some Alkali and Alkaline-Earth Chromates (V). in: Acta Chem. Scand. 1965, 19, pp. 177-184, doi : 10.3891 / acta.chem.scand.19-0177 .

[roempp-1] Entry on barium chromate. In: Römpp Online . Georg Thieme Verlag, accessed on June 27, 2014.

[GESTIS-2] Entry on barium chromate in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .

[alfa-3] ta sheet barium chromate at AlfaAesar, accessed on March 14, 2010 ( PDF )(JavaScript required) .

[4] SS Wise, AL Holmes, Q. Qin, H. Xie, SP Katsifis, WD Thompson, JP Wise: Comparative genotoxicity and cytotoxicity of four hexavalent chromium compounds in human bronchial cells. In: Chemical research in toxicology. Volume 23, number 2, February 2010, pp. 365-372, doi : 10.1021 / tx900363j , PMID 20000473 , PMC 2822000 (free full text).

[Wilhelmi-5] KA Wilhelmi, O. Jonsson: X-Ray Studies on Some Alkali and Alkaline-Earth Chromates (V). in: Acta Chem. Scand. 1965, 19, pp. 177-184, doi : 10.3891 / acta.chem.scand.19-0177 .