Lead(II) chromate
Names | |
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Other names
see text
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Identifiers | |
ChEBI | |
ECHA InfoCard
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100.028.951 |
EC Number |
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PubChem CID
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RTECS number
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UNII | |
UN number | 3288 |
CompTox Dashboard (EPA)
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Properties | |
PbCrO4 | |
Molar mass | 323.192 g/mol |
Appearance | orange-yellow powder |
Density | 6.12 g/cm3, solid |
Melting point | 844 °C (1,551 °F; 1,117 K) |
negligible | |
Solubility | soluble in diluted nitric acid insoluble in acetic acid, ammonia |
−18.0·10−6 cm3/mol | |
Refractive index (nD)
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2.31 |
Structure | |
monoclinic | |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards
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Carcinogen and highly toxic |
GHS labelling: | |
Danger | |
H350, H360, H373, H410 | |
P201, P273, P308+P313, P501 | |
NFPA 704 (fire diamond) | |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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>12 g/kg (mouse, oral) |
Safety data sheet (SDS) | ICSC 0003 Sigma-Aldrich |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Lead(II) chromate is an
Structure
Lead chromate adopts the
Applications
Approximately 37,000 tons were produced in 1996. The main applications are as a pigment in paints, under the name chrome yellow.[5]
Preparation
Lead(II) chromate can be produced by treating sodium chromate with lead salts such as lead(II) nitrate or by combining lead(II) oxide with chromic acid.
Related lead sulfochromate pigments are produced by the replacement of some chromate by sulfate, resulting in a mixed lead-chromate-sulfate compositions Pb(CrO4)1−x(SO4)x. This replacement is possible because sulfate and chromate are isostructural. Since sulfate is colorless, sulfochromates with high values of x are less intensely colored than lead chromate.[5] In some cases, chromate is replaced by molybdate.[1]
Reactions
Heating in
- PbCrO4 + 4 OH− → [Pb(OH)4]2− + CrO2−4
Safety hazards
Despite containing both
In the 1800s, the product was used to impart a bright yellow color to some types of candy.[6] It is used (illegally) to enhance the color of certain spices, particularly turmeric,[7][8] particularly in Bangladesh.[9][10]
Unlike other lead-based paint pigments, lead chromate is still widely used.
See also
References
- ^ S2CID 94606296.
- ^ "Sunflowers - Van Gogh Museum". vangoghmuseum.nl. Archived from the original on 29 October 2016. Retrieved 21 September 2016.
- S2CID 2268072.
- ^ ISBN 978-3527306732.
- ^ Wisconsin. State Board of Health (1887). Progress Report of Public Health in Wisconsin, Volume 10. p. 92. Retrieved 17 July 2013. (Google Books)
- ^ "The American Spice Trade Association's Statement on Lead in Turmeric - ASTA: The Voice of the U.S. Spice Industry in the Global Market". ASTA: The Voice of the U.S. Spice Industry in the Global Market. 28 October 2013. Retrieved 21 November 2018.
- PMID 30462630.
- ^ "Researchers find lead in turmeric". Phys. Stanford University. 24 September 2019. Retrieved 1 October 2019.
- PMID 31550596.