Barium chromate
| Names | |
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| Other names
Barium chromate oxide,
Chromic acid, (BaCrO4), barium salt (1:1), barium tetraoxochromate(VI) |
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3D model (Jmol)
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| ChemSpider | |
| ECHA InfoCard | 100.030.587 |
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PubChem CID
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| RTECS number | CQ876000 |
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| Properties | |
| BaCrO4 | |
| Molar mass | 253.37 g/mol |
| Appearance | yellow powder |
| Density | 4.498 g/cm3 |
| Melting point | 210 °C (410 °F; 483 K) (decomposes) |
| 0.2775 mg/100 mL (20 °C) | |
| Solubility | soluble in strong acids |
| Hazards | |
| Safety data sheet | External MSDS |
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EU classification (DSD) (outdated)
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Harmful (Xn) |
| R-phrases (outdated) | R20/22 |
| S-phrases (outdated) | (S2), S28 |
| NFPA 704 | |
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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 | |
Barium chromate, named barium tetraoxochromate(VI) by the IUPAC, is a yellow sand like powder with the formula BaCrO4. It is a known oxidizing agent and produces a green flame when heated, a result of the barium ions.
The first naturally occurring barium chromate was found in the country of Jordan. The brown crystals found perched on host rocks were named hashemite in honor of the Hashemite Kingdom of Jordan. The hashemite crystals range in color from light yellowish-brown to a darker greenish-brown and are usually less than 1mm in length.
The hashemite crystals are not composed of pure barium chromate but instead contain some small sulfur content as well. The different crystals contain a range of sulfur impurities ranging from the more pure dark crystals, Ba1.00(Cr0.93, S0.07)1.00O4, to the less pure light crystals, Ba1.00(Cr0.64, S0.36)1.00O4.
Hashemite was found to be an isostructural chromate analog of barite, BaWO4.
It can be synthesized by reacting barium hydroxide or barium sulphate with potassium chromate.
Alternatively, it can be created by the interaction of barium chloride with sodium chromate. The precipitate is then washed, filtered, and dried.
It is very insoluble in water, but is soluble in acids:
It can react with barium hydroxide in the presence of sodium azide to create barium chromate(V). The reaction releases oxygen and water.
Barium chromate has been found to be useful in many capacities. The compound is often used as a carrier for the chromium ions. One such case is the use of barium chromate as a sulfate scavenger in chromium electroplating baths. Over time the chromium concentration of the bath will decrease until the bath is no longer functional. Adding barium chromate enhances the life of the bath by adding to the chromic acid concentration.
Barium chromate is an oxidizing agent, making it useful as a burn rate modifier in pyrotechnic compositions. It is especially useful in delay compositions such as delay fuses.
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