Barium chromate

Last updated
Barium chromate
Bariumchromaat.png
Chroman barnaty.jpg
Names
IUPAC name
Barium chromate
Other names
Barium chromate oxide,
Chromic acid, (BaCrO4), barium salt (1:1), barium tetraoxochromate(VI)
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.030.587 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 233-660-5
PubChem CID
RTECS number
  • CQ876000
UNII
UN number 1564
  • InChI=1S/Ba.Cr.4O/q+2;;;;2*-1 Yes check.svgY
    Key: QFFVPLLCYGOFPU-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/Ba.Cr.4O/q+2;;;;2*-1/rBa.CrO4/c;2-1(3,4)5/q+2;-2
    Key: QFFVPLLCYGOFPU-XPTLYTIWAW
  • [Ba+2].[O-][Cr]([O-])(=O)=O
Properties
BaCrO4
Molar mass 253.37 g/mol
Appearanceyellow powder, darkens upon heating
Density 4.498 g/cm3
Melting point 210 °C (410 °F; 483 K) (decomposes)
0.2775 mg/100 mL (20 °C)
1.17 × 10−10 [1]
Solubility soluble in strong acids
Structure
orthorhombic
Hazards
GHS labelling:
GHS-pictogram-rondflam.svg GHS-pictogram-skull.svg GHS-pictogram-exclam.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Danger
H272, H301, H302, H317, H332, H350, H410
P201, P202, P210, P220, P221, P261, P264, P270, P271, P272, P273, P280, P281, P301+P310, P301+P312, P302+P352, P304+P312, P304+P340, P308+P313, P312, P321, P330, P333+P313, P363, P370+P378, P391, P405, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazards (white): no code
3
0
3
Safety data sheet (SDS) External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Barium chromate, 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.

Contents

History

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. [2]

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. [3]

Hashemite was found to be an isostructural chromate analog of baryte, BaSO4. [4]

Preparation and Reactions

It can be synthesized by reacting barium hydroxide or barium chloride 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:

2 BaCrO4 + 2 H+ → 2 Ba2+ + Cr2O72− + H2O
Ksp = [Ba2+][CrO42−] = 2.1 × 10−10

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

Common Uses

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. [5] 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. [6]

Barium chromate is used as a corrosion inhibitive pigment when zinc-alloy electroplating surfaces. [7]

When mixed with solid fumaric acid, barium chromate can be used in the removal of impurities and residual moisture from organic dry-cleaning solvents or from petroleum fuels. [8]

Barium chromate is also used in the composition of a catalyst for alkane dehydrogenation. [9]

Barium has also been used to color paints. The pigment known as lemon yellow often contained barium chromate mixed with lead sulfate. [10] Due to its moderate tinting strength lemon yellow was not employed very frequently in oil painting. [11] Pierre-Auguste Renoir and Claude Monet are known to have painted with lemon yellow. [12]

Research

In 2004 a method was found for making single-crystalline ABO4 type nanorods. This method consisted of a modified template synthesis technique that was originally used for the synthesis of organic microtubules. Nanoparticles are allowed to grow in the pores of alumina membranes of various sizes. The varying sizes of the pores allow the growth to be controlled and cause the shapes to be reproducible. The alumina is then dissolved, leaving the nanoparticles behind intact. The synthesis can be carried out at room temperature, greatly reducing the cost and constrictions on conditions. [13]

In 2010, a study was conducted on four hexavalent chromium compounds to test the carcinogenic effects of chromium. The chromium ions accumulate in the bronchial bifurcation sites, settling into the tissue and inducing tumors. Using zinc chromate as a standard, it was discovered that barium chromate is both genotoxic and cytotoxic. The cytotoxicity was determined to most likely be a result of the genotoxicity, but the cause of the genotoxicity is yet unknown. [14]

Safety

Barium chromate is toxic. Chromates, when pulverized and inhaled, are carcinogens.

Related Research Articles

<span class="mw-page-title-main">Chromium</span> Chemical element, symbol Cr and atomic number 24

Chromium is a chemical element; it has symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal.

Chromic acid is jargon for a solution of formed by the addition of sulfuric acid to aqueous solutions of dichromate. It consists at least in part of chromium trioxide.

<span class="mw-page-title-main">Chromate and dichromate</span> Chromium(VI) anions

Chromate salts contain the chromate anion, CrO2−
4. Dichromate salts contain the dichromate anion, Cr
2O2−
7. They are oxyanions of chromium in the +6 oxidation state and are moderately strong oxidizing agents. In an aqueous solution, chromate and dichromate ions can be interconvertible.

<span class="mw-page-title-main">Crocoite</span> Lead chromate mineral

Crocoite is a mineral consisting of lead chromate, PbCrO4, and crystallizing in the monoclinic crystal system. It is identical in composition with the artificial product chrome yellow used as a paint pigment.

<span class="mw-page-title-main">Copper chromite</span> Chemical compound

Copper chromite is an inorganic compound with the formula Cu2Cr2O5. It is a black solid that is used to catalyze reactions in organic synthesis.

<span class="mw-page-title-main">Potassium chromate</span> Chemical compound

Potassium chromate is the inorganic compound with the formula K2CrO4. This yellow solid is the potassium salt of the chromate anion. It is a common laboratory chemical, whereas sodium chromate is important industrially.

<span class="mw-page-title-main">Silver chromate</span> Chemical compound

Silver chromate is an inorganic compound with formula Ag2CrO4 which appears as distinctively coloured brown-red crystals. The compound is insoluble and its precipitation is indicative of the reaction between soluble chromate and silver precursor salts (commonly potassium/sodium chromate with silver nitrate). This reaction is important for two uses in the laboratory: in analytical chemistry it constitutes the basis for the Mohr method of argentometry, whereas in neuroscience it is used in the Golgi method of staining neurons for microscopy.

<span class="mw-page-title-main">Caesium chromate</span> Chemical compound

Caesium chromate or cesium chromate is an inorganic compound with the formula Cs2CrO4. It is a yellow crystalline solid that is the caesium salt of chromic acid, and it crystallises in the orthorhombic system.

<span class="mw-page-title-main">Zinc chromate</span> Chemical compound

Zinc chromate, ZnCrO4, is a chemical compound, a salt containing the chromate anion, appearing as odorless yellow powder or yellow-green crystals, but, when used for coatings, pigments are often added. It is used industrially in chromate conversion coatings, having been developed by the Ford Motor Company in the 1920s.

<span class="mw-page-title-main">Lead(II) chromate</span> Chemical compound

Lead(II) chromate is the inorganic compound with the formula (PbCrO4). It has a vivid yellow color and is generally insoluble. Two polymorphs of lead chromate are known, orthorhombic and the more stable monoclinic form. Monoclinic lead chromate is used in paints under the name chrome yellow, and many other names. It occurs also as the mineral crocoite.

<span class="mw-page-title-main">Chrome orange</span> Chemical compound and inorganic pigment

Chrome orange is a mixed oxide with the chemical formula Pb2CrO5. It can be made by treating a lead(II) salt with an alkaline solution of a chromate or by treating chrome yellow (PbCrO4) with strongly basic solution.

<span class="mw-page-title-main">Nickel(II) chromate</span> Chemical compound

Nickel(II) chromate (NiCrO4) is an acid-soluble compound, red-brown in color, with high tolerances for heat. It and the ions that compose it have been linked to tumor formation and gene mutation, particularly to wildlife.

<span class="mw-page-title-main">Calcium chromate</span> Chemical compound

Calcium chromate is an inorganic compound with the formula CaCrO4, i.e. the chromate salt of calcium. It is a bright yellow solid which is normally found in the dihydrate form CaCrO4·2H2O. A very rare anhydrous mineral form exists in nature, which is known as chromatite.

Chromium toxicity refers to any poisonous toxic effect in an organism or cell that results from exposure to specific forms of chromium—especially hexavalent chromium. Hexavalent chromium and its compounds are toxic when inhaled or ingested. Trivalent chromium is a trace mineral that is essential to human nutrition. There is a hypothetical risk of genotoxicity in humans if large amounts of trivalent chromium were somehow able to enter living cells, but normal metabolism and cell function prevent this.

<span class="mw-page-title-main">Molybdate</span> Chemical compound of the form –O–MoO₂–O–

In chemistry, a molybdate is a compound containing an oxyanion with molybdenum in its highest oxidation state of 6: O−−Mo(=O)2−O−. Molybdenum can form a very large range of such oxyanions, which can be discrete structures or polymeric extended structures, although the latter are only found in the solid state. The larger oxyanions are members of group of compounds termed polyoxometalates, and because they contain only one type of metal atom are often called isopolymetalates. The discrete molybdenum oxyanions range in size from the simplest MoO2−
4, found in potassium molybdate up to extremely large structures found in isopoly-molybdenum blues that contain for example 154 Mo atoms. The behaviour of molybdenum is different from the other elements in group 6. Chromium only forms the chromates, CrO2−
4, Cr
2O2−
7, Cr
3O2−
10 and Cr
4O2−
13 ions which are all based on tetrahedral chromium. Tungsten is similar to molybdenum and forms many tungstates containing 6 coordinate tungsten.

<span class="mw-page-title-main">Barium manganate</span> Chemical compound

Barium manganate is an inorganic compound with the formula BaMnO4. It is used as an oxidant in organic chemistry. It belongs to a class of compounds known as manganates in which the manganese resides in a +6 oxidation state. Manganate should not be confused with permanganate which contains manganese(VII). Barium manganate is a powerful oxidant, popular in organic synthesis and can be used in a wide variety of oxidation reactions.

George-ericksenite is a mineral with the chemical formula Na6CaMg(IO3)6(CrO4)2(H2O)12. It is vitreous, pale yellow to bright lemon yellow, brittle, and features a prismatic to acicular crystal habit along [001] and somewhat flattened crystal habit on {110}. It was first encountered in 1984 at the Pinch Mineralogical Museum. One specimen of dietzeite from Oficina Chacabuco, Chile had bright lemon-yellow micronodules on it. These crystals produced an X-ray powder diffraction pattern that did not match any XRD data listed for inorganic compounds. The X-ray diffraction pattern and powder mount were set aside until 1994. By then, the entire mineral collection from the Pinch Mineralogical Museum had been purchased by the Canadian Museum of Nature. The specimen was then retrieved and studied further. This study was successful and the new mineral george-ericksenite was discovered. The mineral was named for George E. Ericksen who was a research economic geologist with the U.S. Geological Survey for fifty years. The mineral and name have been approved by Commission on New Minerals and Mineral Names (IMA). The specimen, polished thin section, and the actual crystal used for the structure determination are kept in the Display Series of the National Mineral Collection of Canada at the Canadian Museum of Nature, Ottawa, Ontario.

<span class="mw-page-title-main">Hashemite (mineral)</span>

Hashemite is a very rare barium chromate mineral with the formula Ba(Cr,S)O4. It is a representative of natural chromates - a relatively small and rare group of minerals. Hashemite is the barium-analogue of tarapacáite. It is also the chromium-analogue of baryte, and belongs to the baryte group of minerals. Hashemite is stoichiometrically similar to crocoite and chromatite. Hashemite is orthorhombic, with space group Pnma. I was found together with chromium-bearing ettringite and an apatite group mineral in the Hatrurim Formation, known for the occurrence of rocks formed due to natural pyrometamorphism. Hashemite is named after the Hashemite Kingdom of Jordan.

References

  1. ↑ John Rumble (June 18, 2018). CRC Handbook of Chemistry and Physics (99th ed.). CRC Press. pp. 4–47. ISBN   978-1138561632.
  2. ↑ Hauff, Phoebe L; Foord, Eugene E; Rosenblum, Sam; and Hakki, Walid. (1983) "Hashemite, Ba(Cr,S)O4, a new mineral from Jordan." American Mineralogist, 69, 1223-1225.
  3. ↑ Hauff, Phoebe L; Foord, Eugene E; Rosenblum, Sam; and Hakki, Walid. (1983) "Hashemite, Ba(Cr,S)O4, a new mineral from Jordan." American Mineralogist, 69, 1223-1225.
  4. ↑ Hauff, Phoebe L; Foord, Eugene E; Rosenblum, Sam; and Hakki, Walid. (1983) "Hashemite, Ba(Cr,S)O4, a new mineral from Jordan." American Mineralogist, 69, 1223-1225.
  5. ↑ Jones, Allen R; Meng, John; Newboy, Kenneth R. (1993) Use of barium chromate as a sulfate scavenger in chromium electroplating baths" US Patent No. 5207890 A.
  6. ↑ Espagnacq, Andre; Morand, Philippe. (1997) "Pyrotechnic composition for delay fuses" EP Patent No 0630876 B1.
  7. ↑ Fountoulakis, Stavros G; Humayan, Arif; Lezzi, Robert A. (1985) "Electroplated product and method" EP Patent No. 0140564 A2.
  8. ↑ Jackson, Herman R. (1993) "SOlid fumaric acid-solid barium chromate catalyst for removing impurities and residual moisture and method for its use" US Patent No. 5154726 A.
  9. ↑ Ruettinger, Wolfgang; Jacubinas, Richard. (2013) "Chromia Alumina Catalysts for Alkane Dehydrogenation" US Patent No. 20130072739 A1.
  10. ↑ Douma, M. curator. (2008) Pigments through the Ages. Institute for Dynamic Educational Development. http://www.webexhibits.org/pigments/
  11. ↑ Kühn, H. and Curran, M., Strontium, Barium and Calcium Chromates, in Artists' Pigments. A Handbook of Their History and Characteristics, Vol. 1: Feller, R.L. (Ed.) Oxford University Press 1986, p. 205 – 207.
  12. ↑ Lemon yellow, ColourLex
  13. ↑ Mao, Yuanbing; Wong, Stanislaus S. (2004) "General, Room-Temperature Method for the Synthesis and well as Arrays of Single-Crystalline ABO4− Type Nanorods." J. Am. Chem. Soc. 126(46), 15245-15252.
  14. ↑ Wise, Sandra S; Holmes, Amie L; Qin,Qin; Xie, Hong; Kafsifis, Spiros P; Thompson, W Douglas; Wise, John Pierce Sr. (2010) "Comparative Genotoxicity and Cytotoxicity of Four Haxevalent Chromium Compounds in Human Bronchial Cells." Chem. Res. Toxicol. 23, 365-372.

Further study

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