Scheele's Green
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| Names | |
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IUPAC name
copper hydrogen arsenite
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| Other names
Copper arsenite
Copper arsenate Swedish Green Cupric Green |
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| Identifiers | |
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.030.573 |
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PubChem CID
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| Properties | |
| AsCuHO3 | |
| Molar mass | 187.474 |
| Hazards | |
| US health exposure limits (NIOSH): | |
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PEL (Permissible)
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[1910.1018] TWA 0.010 mg/m3 |
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REL (Recommended)
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Ca C 0.002 mg/m3 [15-minute] |
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IDLH (Immediate danger)
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Ca [5 mg/m3 (as As)] |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is   ?) |
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| Infobox references | |
Scheele's Green, also called Schloss Green, is chemically a cupric hydrogen arsenite (also called copper arsenite or acidic copper arsenite), CuHAsO
3. It is chemically related to Paris Green. It is a yellowish-green pigment which in the past was used in some paints, but has since fallen out of use because of its toxicity and the instability of its color in the presence of sulfides and various chemical pollutants.
Scheele's Green was invented in 1775 by Carl Wilhelm Scheele. By the end of the 19th century, it had virtually replaced the older green pigments based on copper carbonate.
The pigment was originally prepared by making a solution of sodium carbonate at a temperature of around 90 °C, then slowly adding arsenious oxide, while constantly stirring until everything had dissolved. This produced a sodium arsenite solution. Added to a copper sulfate solution, it produced a green precipitate of effectively insoluble copper arsenite. After filtration the product was dried at about 43 °C. To enhance the color, the salt was subsequently heated to 60–70 °C. The intensity of the color depends on the copper : arsenic ratio, which in turn was affected by the ratio of the starting materials, as well as the temperature.
It has been found that Scheele's green was composed of a variety of different compounds, including copper metaarsenite (CuO·As
2O
3), copper arsenite salt (CuHAsO
3 and Cu(AsO
3)
2·3H
2O)), neutral copper orthoarsenite (3CuO·As
2O
3·2H
2O), copper arsenate (CuAsO
2 and Cu(AsO
2)
2), and copper diarsenite (2CuO·As
2O
3·2H
2O).
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