Nickel(II) chromate

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Nickel chromate
Nickel chromate.JPG
Nickel chromate formula.svg
Names
IUPAC name
Nickel(II) chromate
Other names
nickelous chromate
nickel chromate
nickel(II) chromium(VI) oxide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.035.227 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 238-766-5
PubChem CID
  • InChI=1S/Cr.Ni.4O/q;+2;;;2*-1
    Key: QGAXAFUJMMYEPE-UHFFFAOYSA-N
  • [O-][Cr](=O)(=O)[O-].[Ni+2]
Properties
NiCrO4
Molar mass 174.71 g/mol
Appearancedark maroon-colored powder
very slightly soluble in water [1]
Solubility soluble in hydrochloric acid
Hazards
Flash point Non-flammable
Related compounds
Other anions
nickel(II) molybdate
nickel(II) tungstate
Other cations
magnesium chromate
cadmium chromate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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. [2]

Contents

Synthesis

Nickel(II) chromate can be formed in the lab by heating a mixture of chromium(III) oxide and nickel oxide at between 700 °C and 800 °C under oxygen at 1000 atm pressure. It can be produced at 535 °C and 7.3 bar oxygen, but the reaction takes days to complete. [3] If the pressure is too low or temperature too high but above 660 °C, then the nickel chromium spinel NiCr2O4 forms instead. [3]

Karin Brandt also claimed to make nickel chromate using a hydrothermal technique. [4] [5]

Precipitates of Ni2+ ions with chromate produce a brown substance that contains water. [6]

Properties

The structure of nickel chromate is the same as for chromium vanadate, CrVO4. Crystals have an orthorhombic structure with unit cell sizes a = 5.482 Å, b = 8.237 Å, c = 6.147 Å. The cell volume is 277.6 Å3 with four formula per unit cell. [5] [7]

Nickel chromate is dark in colour, unlike most other chromates which are yellow. [3] The infrared spectrum of nickel chromate show two sets of absorption bands. The first includes lines at 925, 825, and 800 cm−1 due to Cr-O stretching, and the second has lines at 430, 395, 365 (very weak) due to Cr-O rock and bend and 310 cm−1 produced from Ni-O stretching. [8]

Reaction

When heated at lower oxygen pressure around 600 °C, nickel chromate decomposes to the nickel chromite spinel, nickel oxide and oxygen. [3]

4 NiCrO4→ 2 NiCr2O4 + 2 NiO + 3 O2 (gas)

Nickel chromates can also crystallize with ligands. For instance, with 1,10-phenanthroline it can form triclinic olive-colored crystals of [Ni(1,10-phenanthroline)CrO4•3H2O]•H2O, orange crystals of Ni(1,10-phenanthroline)3Cr2O7•3H2O, and yellow powdered Ni(1,10-phenanthroline)3Cr2O7•8H2O. [6]

Related Research Articles

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

Chromium is a chemical element with the 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.

<span class="mw-page-title-main">Corundum</span> Oxide mineral

Corundum is a crystalline form of aluminium oxide typically containing traces of iron, titanium, vanadium and chromium. It is a rock-forming mineral. It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. Corundum has two primary gem varieties: ruby and sapphire. Rubies are red due to the presence of chromium, and sapphires exhibit a range of colors depending on what transition metal is present. A rare type of sapphire, padparadscha sapphire, is pink-orange.

<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">Chromite</span> Crystalline mineral

Chromite is a crystalline mineral composed primarily of iron(II) oxide and chromium(III) oxide compounds. It can be represented by the chemical formula of FeCr2O4. It is an oxide mineral belonging to the spinel group. The element magnesium can substitute for iron in variable amounts as it forms a solid solution with magnesiochromite (MgCr2O4). A substitution of the element aluminium can also occur, leading to hercynite (FeAl2O4). Chromite today is mined particularly to make stainless steel through the production of ferrochrome (FeCr), which is an iron-chromium alloy.

In inorganic chemistry and materials chemistry, a ternary compound or ternary phase is a chemical compound containing three different elements.

Plating is a surface covering in which a metal is deposited on a conductive surface. Plating has been done for hundreds of years; it is also critical for modern technology. Plating is used to decorate objects, for corrosion inhibition, to improve solderability, to harden, to improve wearability, to reduce friction, to improve paint adhesion, to alter conductivity, to improve IR reflectivity, for radiation shielding, and for other purposes. Jewelry typically uses plating to give a silver or gold finish.

<span class="mw-page-title-main">Chromium trioxide</span> Chemical compound

Chromium trioxide (also known as chromium(VI) oxide or chromic anhydride) is an inorganic compound with the formula CrO3. It is the acidic anhydride of chromic acid, and is sometimes marketed under the same name. This compound is a dark-purple solid under anhydrous conditions, bright orange when wet and which dissolves in water concomitant with hydrolysis. Millions of kilograms are produced annually, mainly for electroplating. Chromium trioxide is a powerful oxidiser and a carcinogen.

<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">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">Chromium compounds</span> Chemical compounds containing chromium

Chromium is a member of group 6, of the transition metals. The +3 and +6 states occur most commonly within chromium compounds, followed by +2; charges of +1, +4 and +5 for chromium are rare, but do nevertheless occasionally exist.

<span class="mw-page-title-main">Ammonium dichromate</span> Chemical compound

Ammonium dichromate is an inorganic compound with the formula (NH4)2Cr2O7. In this compound, as in all chromates and dichromates, chromium is in a +6 oxidation state, commonly known as hexavalent chromium. It is a salt consisting of ammonium ions and dichromate ions.

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

Sodium chromate is the inorganic compound with the formula Na2CrO4. It exists as a yellow hygroscopic solid, which can form tetra-, hexa-, and decahydrates. It is an intermediate in the extraction of chromium from its ores.

<span class="mw-page-title-main">Chromium(VI) oxide peroxide</span> Chemical compound

Chromium(VI) peroxide or chromium oxide peroxide is an unstable compound with the formula CrO5. This compound contains one oxo ligand and two peroxo ligands, making a total of five oxygen atoms per chromium atom.

<span class="mw-page-title-main">Chromite (compound)</span>

In chemistry the term chromite has been used in two contexts. Under IUPAC naming conventions, chromate(III) is preferred to chromite.

  1. For compounds containing an oxyanion of chromium in oxidation state 3
  2. For other compounds of chromium(III) as a means of distinguishing a chemical species such as hexacyanochromite(III). [Cr(CN)6]3− from an analogous compound in which chromium is a different oxidation state.
<span class="mw-page-title-main">Molybdate</span>

In chemistry a molybdate is a compound containing an oxoanion with molybdenum in its highest oxidation state of 6. Molybdenum can form a very large range of such oxoanions which can be discrete structures or polymeric extended structures, although the latter are only found in the solid state. The larger oxoanions 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 oxoanions 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.

A chromate ester is a chemical structure that contains a chromium atom (symbol Cr) in a +6 oxidation state that is connected via an oxygen (O) linkage to a carbon (C) atom. The Cr itself is in its chromate form, with several oxygens attached, and the Cr–O–C attachment makes this chemical group structurally similar to other ester functional groups. They can be synthesized from various chromium(VI) metal compounds, such as CrO3, chromium chloride complexes, and aqueous chromate ions, and tend to react via redox reactions to liberate chromium(IV).

<span class="mw-page-title-main">Chromium cycle</span> Biogeochemical cycle

The chromium cycle is the biogeochemical cycle of chromium through the atmosphere, hydrosphere, biosphere and lithosphere.

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

Potassium hypochromate is a chemical compound with the formula K3CrO4 with the unusual Cr5+ ion. This compound is unstable in water but stable in alkaline solution and was found to have a similar crystal structure to potassium hypomanganate.

Europium(III) chromate is an chemical compound composed of europium, chromium and oxygen with europium in the +3 oxidation state, chromium in the +5 oxidation state and oxygen in the -2 oxidation state. It has the chemical formula of EuCrO4.

References

  1. ↑ Perry, Dale L. (19 April 2016). Handbook of Inorganic Compounds, Second Edition. CRC Press. p. 290. ISBN   9781439814628.
  2. ↑ Eisler, R. (1998). Nickel Hazards to Fish, Wildlife, and Invertebrates: a Synoptic Review. Laurel: U.S. Geological Survey
  3. 1 2 3 4 Muller, Olaf; Roy, Rustum; White, William B. (December 1968). "Phase Equilibria in the Systems NiO-Cr2,O3,-O2, MgO-Cr2O3-O2, and CdO-Cr2,O3,-O2, at High Oxygen Pressures". Journal of the American Ceramic Society. 51 (12): 693–699. doi:10.1111/j.1151-2916.1968.tb15930.x.
  4. ↑ Brandt, Karin (1943). "X-Ray Analysis of CrVO4 and isomorphous compounds". Arkiv för Kemi, Mineralogi och Geologi. 17A (6): 1–13. (not consulted)
  5. 1 2 Muller, Olaf; White, William B.; Roy, Rustum (September 1969). "X-ray diffraction study of the chromates of nickel, magnesium and cadmium". Zeitschrift für Kristallographie. 130 (1–6): 112–120. Bibcode:1969ZK....130..112M. doi:10.1524/zkri.1969.130.1-6.112.
  6. 1 2 Bronowska, W; Staszak, Z; Daszkiewicz, M; Cieślak-Golonka, M; Wojciechowska, A (May 2002). "Systematic investigation of the [Ni2+–phen–CrO42−] system; dichromate species isolated from alkaline solutions". Polyhedron. 21 (9–10): 997–1003. doi:10.1016/S0277-5387(02)00912-9.
  7. ↑ Baran, E. J (May 1998). "Materials belonging to the CrVO4 structure type: preparation, crystal chemistry and physicochemical properties". Journal of Materials Science. 33 (10): 2479–2497. Bibcode:1998JMatS..33.2479B. doi:10.1023/A:1004380530309. S2CID   97516785.
  8. ↑ Muller, Olaf; White, William B.; Roy, Rustum (August 1969). "Infrared spectra of the chromates of magnesium, nickel and cadmium". Spectrochimica Acta Part A: Molecular Spectroscopy. 25 (8): 1491–1499. Bibcode:1969AcSpA..25.1491M. doi:10.1016/0584-8539(69)80133-9.
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