Barium chromate

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Barium chromate
Names
IUPAC name
Barium chromate
Other names
Barium chromate oxide
Barium tetraoxochromate(VI)
Properties
BaCrO4
Molar mass 253.37 g/mol
Appearance Yellow solid
Odor Odorless
Density 4.498 g/cm3 (20 °C)
Melting point 210–1,380 °C (410–2,516 °F; 483–1,653 K) (decomposition)
Boiling point Decomposes
0.0002775 g/100 ml (20 °C)
Solubility Soluble in strong acids
Vapor pressure ~0 mmHg
Thermochemistry
172 J·mol-1·K-1
-1,429 kJ/mol
Hazards
Safety data sheet LobaChemie
Flash point Non-flammable
Related compounds
Related compounds
Potassium chromate
Sodium chromate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Barium chromate or barium tetraoxochromate(VI) is a yellow solid compound with the chemical formula BaCrO4.

It can be found in nature as the mineral Hashemite, although the natural mineral often has sulfur in its composition.

Properties

Chemical

Barium chromate react with barium hydroxide in the presence of sodium azide to create barium chromate(V). The reaction releases oxygen and water.

BaCrO4 + Ba(OH)2 → 2 Ba3(CrO4)2 + O2 + 2 H2O

Physical

Barium chromate is a yellowish powdered solid, practically insoluble in water, but more soluble in conc. acids.

Availability

Barium chromate is sold by chemical suppliers.

Preparation

Barium chromate can be prepared by adding a solution of a soluble barium salt, like barium chloride, to a solution of potassium or sodium chromate:

BaCl2 + K2CrO4 → BaCrO4 + 2 KCl
BaCl2 + Na2CrO4 → BaCrO4 + 2 NaCl

The resulting barium chromate precipitates out of the solution as an insoluble yellow powder.

Projects

  • Compound collecting
  • Yellow paint
  • Sulfate scavenger in chromium electroplating baths
  • Oxidizing agent in pyrotechnic mixtures
  • Corrosion inhibition pigment
  • Catalyst for alkane dehydrogenation

Handling

Safety

Barium chromate is toxic if ingested or inhaled. It is genotoxic and cytotoxic, as chromates are confirmed carcinogens.

Storage

In closed plastic bottles.

Disposal

Can be taken to hazardous waste companies.

Alternatively, one can convert the compound to barium sulfate, while the Cr(VI) can be reduced to Cr(III). The neutralization products can then be dumped in trash.

References

Relevant Sciencemadness threads