Chromium(III) hydroxide

Last updated
Chromium(III) hydroxide
Chromium(III) hydroxide.svg
Names
IUPAC name
Chromium(3+) hydroxide
Identifiers
3D model (JSmol)
ECHA InfoCard 100.013.781 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
RTECS number
  • GB2670000
UNII
  • InChI=1S/Cr.3H2O/h;3*1H2
    Key: LXMQZGGLHVSEBA-UHFFFAOYSA-N
  • ionic form:[OH-].[OH-].[OH-].[Cr+++]
  • coordination form:O[Cr](O)O
Properties
Cr(OH)3
Molar mass 103.02 g/mol
Appearancegreen, gelatinous precipitate
Density 3.11 g/cm3
insoluble
Hazards
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 1 mg/m3 [1]
REL (Recommended)
TWA 0.5 mg/m3 [1]
IDLH (Immediate danger)
250 mg/m3 [1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Chromium(III) hydroxide is a gelatinous green inorganic compound with the chemical formula Cr(OH)3. It is a polymer with an undefined structure and low solubility. It is amphoteric, dissolving in both strong alkalis and strong acids. [2]

In alkali:
In acid:

It is used as a pigment, as a mordant, and as a catalyst for organic reactions. [3]

It is manufactured by adding a solution of ammonium hydroxide to a solution of chromium salt.

Pure Cr(OH)3 is as yet (2020) unknown among the mineral species. However, three natural polymorphs of the oxyhydroxide, CrO(OH), are known: bracewellite, grimaldiite and guyanaite. [4] [5] [6] [7]

Related Research Articles

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

Hydroxide is a diatomic anion with chemical formula OH. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, a ligand, a nucleophile, and a catalyst. The hydroxide ion forms salts, some of which dissociate in aqueous solution, liberating solvated hydroxide ions. Sodium hydroxide is a multi-million-ton per annum commodity chemical. The corresponding electrically neutral compound HO is the hydroxyl radical. The corresponding covalently bound group –OH of atoms is the hydroxy group. Both the hydroxide ion and hydroxy group are nucleophiles and can act as catalysts in organic chemistry.

<span class="mw-page-title-main">Sodium hydroxide</span> Chemical compound with formula NaOH

Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations Na+ and hydroxide anions OH.

<span class="mw-page-title-main">Potassium hydroxide</span> Inorganic compound (KOH)

Potassium hydroxide is an inorganic compound with the formula KOH, and is commonly called caustic potash.

<span class="mw-page-title-main">Calcium hydroxide</span> Inorganic compound of formula Ca(OH)2

Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca(OH)2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed or slaked with water. It has many names including hydrated lime, caustic lime, builders' lime, slaked lime, cal, and pickling lime. Calcium hydroxide is used in many applications, including food preparation, where it has been identified as E number E526. Limewater, also called milk of lime, is the common name for a saturated solution of calcium hydroxide.

<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
2
O2−
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">Potassium dichromate</span> Chemical compound

Potassium dichromate, K2Cr2O7, is a common inorganic chemical reagent, most commonly used as an oxidizing agent in various laboratory and industrial applications. As with all hexavalent chromium compounds, it is acutely and chronically harmful to health. It is a crystalline ionic solid with a very bright, red-orange color. The salt is popular in the laboratory because it is not deliquescent, in contrast to the more industrially relevant salt sodium dichromate.

<span class="mw-page-title-main">Chromium(III) chloride</span> Chemical compound

Chromium(III) chloride (also called chromic chloride) describes any of several chemical compounds with the formula CrCl3 · xH2O, where x can be 0, 5, and 6. The anhydrous compound with the formula CrCl3 is a violet solid. The most common form of the trichloride is the dark green hexahydrate, CrCl3 · 6 H2O. Chromium chlorides find use as catalysts and as precursors to dyes for wool.

<span class="mw-page-title-main">Tin(II) oxide</span> Chemical compound, stannous oxide (SnO)

Tin(II) oxide is a compound with the formula SnO. It is composed of tin and oxygen where tin has the oxidation state of +2. There are two forms, a stable blue-black form and a metastable red form.

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

Chromium(III) oxide is an inorganic compound with the formula Cr
2
O
3
. It is one of the principal oxides of chromium and is used as a pigment. In nature, it occurs as the rare mineral eskolaite.

<span class="mw-page-title-main">Beryllium nitride</span> Chemical compound

Beryllium nitride, Be3N2, is a nitride of beryllium. It can be prepared from the elements at high temperature (1100–1500 °C); unlike beryllium azide or BeN6, it decomposes in vacuum into beryllium and nitrogen. It is readily hydrolysed forming beryllium hydroxide and ammonia. It has two polymorphic forms cubic α-Be3N2 with a defect anti-fluorite structure, and hexagonal β-Be3N2. It reacts with silicon nitride, Si3N4 in a stream of ammonia at 1800–1900 °C to form BeSiN2.

<span class="mw-page-title-main">Copper(II) hydroxide</span> Hydroxide of copper

Copper(II) hydroxide is the hydroxide of copper with the chemical formula of Cu(OH)2. It is a pale greenish blue or bluish green solid. Some forms of copper(II) hydroxide are sold as "stabilized" copper(II) hydroxide, although they likely consist of a mixture of copper(II) carbonate and hydroxide. Cupric hydroxide is a strong base, although its low solubility in water makes this hard to observe directly.

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

Silver oxide is the chemical compound with the formula Ag2O. It is a fine black or dark brown powder that is used to prepare other silver compounds.

<span class="mw-page-title-main">Beryllium hydroxide</span> Chemical compound

Beryllium hydroxide, Be(OH)2, is an amphoteric hydroxide, dissolving in both acids and alkalis. Industrially, it is produced as a by-product in the extraction of beryllium metal from the ores beryl and bertrandite. The natural pure beryllium hydroxide is rare (in form of the mineral behoite, orthorhombic) or very rare (clinobehoite, monoclinic). When alkali is added to beryllium salt solutions the α-form (a gel) is formed. If this left to stand or boiled, the rhombic β-form precipitates. This has the same structure as zinc hydroxide, Zn(OH)2, with tetrahedral beryllium centers.

Zinc hydroxide Zn(OH)2 is an inorganic chemical compound. It also occurs naturally as 3 rare minerals: wülfingite (orthorhombic), ashoverite and sweetite (both tetragonal).

<span class="mw-page-title-main">Chromium(III) sulfate</span> Chemical compound

Chromium(III) sulfate usually refers to the inorganic compounds with the formula Cr2(SO4)3.x(H2O), where x can range from 0 to 18. Additionally, ill-defined but commercially important "basic chromium sulfates" are known. These salts are usually either violet or green solids that are soluble in water. It is commonly used in tanning leather.

In inorganic chemistry, olation is the process by which metal ions form polymeric oxides in aqueous solution. The phenomenon is important for understanding the relationship between metal aquo complexes and metal oxides, which are represented by many minerals.

Indium(III) hydroxide is the chemical compound with the formula In(OH)3. Its prime use is as a precursor to indium(III) oxide, In2O3. It is sometimes found as the rare mineral dzhalindite.

<span class="mw-page-title-main">Guyanaite</span>

Guyanaite (CrOOH) is a chromium oxide mineral that forms as an intergrowth with other chromium oxide minerals known as bracewellite (CrOOH) and grimaldiite (CrOOH) as well as eskolaite (Cr2O3) which in early findings were nearly indistinguishable from one another. These oxides formed so closely as intergrowths with one another that they were initially, and erroneously, identified as a single definite mineral previously known as merumite. Because of its complex history and the previously undiscovered nature of these chromium oxide polymorphs, the relevance of any information found in many early experiments involving the mineral formerly known as merumite in regard to guyanaite is unknown and it is implied that in any further reference of merumite it will have been composed of a mineral assemblage including guyanaite. The rare occurrence and complexity from intergrowth of naturally occurring guyanaite hinders experimental work, leading to laboratory synthesized samples which help to better experiment with the minerals.

<span class="mw-page-title-main">Chromium(III) phosphate</span> Chemical compound

Chromium(III) phosphate describes inorganic compounds with the chemical formula CrPO4.(H2O)n, where n = 0, 4, or 6. All are deeply colored solids. Anhydrous CrPO4 is green. The hexahydrate CrPO4•6H2O is violet.

Scandium(III) hydroxide is an inorganic compound with the chemical formula Sc(OH)3, the trivalent hydroxide of scandium. It is an amphoteric compound. It is slightly soluble in water, and its saturated solution (pH = 7.85) contains Sc(OH)3 and a small amount of Sc(OH)2+. The solubility of scandium(III) hydroxide in water is 0.0279 mol/L. It will convert to ScO(OH) after aging, greatly reducing the solubility (0.0008 mol/L). Scandium(III) hydroxide can be produced by reacting scandium salts and alkali hydroxides. In the reaction, different starting ingredients can generate different intermediates such as Sc(OH)1.75Cl1.25, Sc(OH)2NO3 and Sc(OH)2.32(SO4)0.34.

References

  1. 1 2 3 NIOSH Pocket Guide to Chemical Hazards. "#0141". National Institute for Occupational Safety and Health (NIOSH).
  2. Rai, Dhanpat; Sass, Bruce M.; Moore, Dean A. "Chromium(III) hydrolysis constants and solubility of chromium(III) hydroxide" Inorganic Chemistry 1987, volume 26, pp. 345-9. doi : 10.1021/ic00250a002
  3. Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1985). "Chromium". Lehrbuch der Anorganischen Chemie (in German) (91–100 ed.). Walter de Gruyter. pp. 1081–1095. ISBN   3-11-007511-3.
  4. "Bracewellite".
  5. "Grimaldiite".
  6. "Guyanaite".
  7. "List of Minerals". 21 March 2011.