Chromium(III) sulfate

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Chromium(III) sulfate
Chromium(III) sulfate.jpg
Cr(III)(aq)6)sulfate.svg
Names
IUPAC name
Chromium(III) sulfate
Other names
Basic chromium sulfate, chromic sulfate
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.030.217 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 233-253-2
PubChem CID
UNII
UN number 2240 3077
  • InChI=1S/2Cr.3H2O4S.12H2O/c;;3*1-5(2,3)4;;;;;;;;;;;;/h;;3*(H2,1,2,3,4);12*1H2/q2*+3;;;;;;;;;;;;;;;/p-6 X mark.svgN
    Key: ANNXSSGQVXBUEI-UHFFFAOYSA-H X mark.svgN
  • InChI=1/2Cr.3H2O4S.12H2O/c;;3*1-5(2,3)4;;;;;;;;;;;;/h;;3*(H2,1,2,3,4);12*1H2/q2*+3;;;;;;;;;;;;;;;/p-6
    Key: ANNXSSGQVXBUEI-CYFPFDDLAL
  • anhydrous:[Cr+3].[Cr+3].[O-]S(=O)(=O)[O-].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O
  • dodecahydrate:[OH2+][Cr-3]([OH2+])([OH2+])([OH2+])([OH2+])[OH2+].[OH2+][Cr-3]([OH2+])([OH2+])([OH2+])([OH2+])[OH2+].[O-]S(=O)(=O)[O-].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O
Properties
Cr2(SO4)3 • 12H2O
Molar mass 392.16 g/mol
608.363 g/mol (dodecahydrate)

716.45 g/mol (octadecahydrate)

Appearancereddish-brown crystals (anhydrous), purple crystals (hydrated)
Density 3.10 g/cm3 (anhydrous)
1.86 g/cm3 (pentadecahydrate)
1.709 g/cm3 (octadecahydrate)
Melting point 90 °C
Boiling point >700 °C (decomposes to chromic acid)
insoluble (anhydrous)
soluble (hydrated)
Solubility soluble in alcohol
practically insoluble in acid
+11,800·10−6 cm3/mol
Hazards
GHS labelling:
GHS-pictogram-acid.svg GHS-pictogram-exclam.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Warning
H314, H317, H332, H334, H335, H340, H350, H373, H412
P201, P202, P260, P261, P264, P271, P272, P273, P280, P281, P285, P301+P330+P331, P302+P352, P303+P361+P353, P304+P312, P304+P340, P304+P341, P305+P351+P338, P308+P313, P310, P312, P314, P321, P333+P313, P342+P311, P363, P403+P233, P405, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
0
0
Flash point Non-flammable
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]
Safety data sheet (SDS) MSDS
Related compounds
Other cations
Aluminium sulfate
Related double salts
Chrome alum
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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.

Contents

Chromium(III) sulfates

Three chromium(III) sulfates are well characterized:

A variety of other chromium(III) sulfates are known, but also contain hydroxide or oxide ligands. Most important commercially is basic chromium sulfate, which is thought to be [Cr2(H2O)6(OH)4]SO4 (CAS#39380-78-4). [2] It results from the partial neutralization of the hexahydrates. Other chromium(III) hydroxides have been reported. [3]

Structure of solid Cr(SO4)(H2O)(OH), showing the CrO6 coordination sphere typical of many chromium(III) compounds. Color code: red = O, yellow = S, dark blue = Cr. EntryWithCollCode26550.png
Structure of solid Cr(SO4)(H2O)(OH), showing the CrO6 coordination sphere typical of many chromium(III) compounds. Color code: red = O, yellow = S, dark blue = Cr.

Production

Chromium(III) sulfate are commonly obtained from the wastes of chromate oxidations of various organic compounds. Anthraquinone and quinone are produced on large scale by the x treatment of respectively anthracene and phenol with chromic acid. A chromium(III) oxide byproduct is generated, which is readily extracted into sulfuric acid. Evaporation of these acidic solutions affords salts if hydrate chromium(III) sulfate. Extraction of chromite ore with sulfuric acid in the presence of some chromate gives solutions of chromium(III) sulfate contaminated with other metal ions. Similarly, dissolution of chrome alloys gives chromium(III) sulfate together with ferrous sulfate. [4]

Basic chromium(III) sulfate

Basic chromium sulfate is produced from chromate salts by reduction with sulfur dioxide, although other methods exist. [4] [5] The reduction could formally be written:

Na2Cr2O7 + 3 SO2 + H2O → Cr2(SO4)3 + 2 NaOH

Since 33% of the anion charges are due to hydroxy ions the basicity is 33% (but in tanning jargon it is known as 33% reduced). Products with higher basicities, e.g. 42% or 50% may be obtained by the addition of sodium carbonate, these are often used in combination with sodium formate. The sodium sulfate is often left in the technical product since it is inert with respect to the tanning process.

Natural occurrence

Three complex minerals that are in part Cr(III) sulfates: bentorite, reddingtonite, and putnisite. [6] [7] [8] [9]

Related Research Articles

<span class="mw-page-title-main">Chromium</span> Chemical element with atomic number 24 (Cr)

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.

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

Iron(II) sulfate (British English: iron(II) sulphate) or ferrous sulfate denotes a range of salts with the formula FeSO4·xH2O. These compounds exist most commonly as the heptahydrate (x = 7) but several values for x are known. The hydrated form is used medically to treat or prevent iron deficiency, and also for industrial applications. Known since ancient times as copperas and as green vitriol (vitriol is an archaic name for hydrated sulfate minerals), the blue-green heptahydrate (hydrate with 7 molecules of water) is the most common form of this material. All the iron(II) sulfates dissolve in water to give the same aquo complex [Fe(H2O)6]2+, which has octahedral molecular geometry and is paramagnetic. The name copperas dates from times when the copper(II) sulfate was known as blue copperas, and perhaps in analogy, iron(II) and zinc sulfate were known respectively as green and white copperas.

Chromic acid is jargon for a solution 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">Calcium sulfate</span> Laboratory and industrial chemical

Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO4 and related hydrates. In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. One particular hydrate is better known as plaster of Paris, and another occurs naturally as the mineral gypsum. It has many uses in industry. All forms are white solids that are poorly soluble in water. Calcium sulfate causes permanent hardness in water.

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

Cadmium sulfate is the name of a series of related inorganic compounds with the formula CdSO4·xH2O. The most common form is the monohydrate CdSO4·H2O, but two other forms are known CdSO4·83H2O and the anhydrous salt (CdSO4). All salts are colourless and highly soluble in water.

<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 laboratories 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) is an inorganic chemical compound with the chemical formula CrCl3. It forms several hydrates with the formula CrCl3·nH2O, among which are hydrates where n can be 5 (chromium(III) chloride pentahydrate CrCl3·5H2O) or 6 (chromium(III) chloride hexahydrate CrCl3·6H2O). The anhydrous compound with the formula CrCl3 are violet crystals, while the most common form of the chromium(III) chloride are the dark green crystals of hexahydrate, CrCl3·6H2O. Chromium chlorides find use as catalysts and as precursors to dyes for wool.

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

Chromium trioxide 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 and bright orange when wet. The substance dissolves in water accompanied by hydrolysis. Millions of kilograms are produced annually, mainly for electroplating. Chromium trioxide is a powerful oxidiser, a mutagen, and a carcinogen.

<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">Chromium(II) acetate</span> Chemical compound

Chromium(II) acetate hydrate, also known as chromous acetate, is the coordination compound with the formula Cr2(CH3CO2)4(H2O)2. This formula is commonly abbreviated Cr2(OAc)4(H2O)2. This red-coloured compound features a quadruple bond. The preparation of chromous acetate once was a standard test of the synthetic skills of students due to its sensitivity to air and the dramatic colour changes that accompany its oxidation. It exists as the dihydrate and the anhydrous forms.

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

Chromium(III) fluoride is an inorganic compound with the chemical formula CrF3. It forms several hydrates. The compound CrF3 is a green crystalline solid that is insoluble in common solvents, but the hydrates [Cr(H2O)6]F3 (violet) and [Cr(H2O)6]F3·3H2O (green) are soluble in water. The anhydrous form sublimes at 1100–1200 °C.

<span class="mw-page-title-main">Sodium dichromate</span> Inorganic compound

Sodium dichromate is the inorganic compound with the formula Na2Cr2O7. However, the salt is usually handled as its dihydrate Na2Cr2O7·2H2O. Virtually all chromium ore is processed via conversion to sodium dichromate and virtually all compounds and materials based on chromium are prepared from this salt. In terms of reactivity and appearance, sodium dichromate and potassium dichromate are very similar. The sodium salt is, however, around twenty times more soluble in water than the potassium salt (49 g/L at 0 °C) and its equivalent weight is also lower, which is often desirable.

Indium(III) sulfate (In2(SO4)3) is a sulfate salt of the metal indium. It is a sesquisulfate, meaning that the sulfate group occurs 11/2 times as much as the metal. It may be formed by the reaction of indium, its oxide, or its carbonate with sulfuric acid. An excess of strong acid is required, otherwise insoluble basic salts are formed. As a solid indium sulfate can be anhydrous, or take the form of a pentahydrate with five water molecules or a nonahydrate with nine molecules of water. Indium sulfate is used in the production of indium or indium containing substances. Indium sulfate also can be found in basic salts, acidic salts or double salts including indium alum.

<span class="mw-page-title-main">Chromium compounds</span> Chemical compounds containing chromium

Chromium compounds are compounds containing the element chromium (Cr). 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">Chromium(III) nitrate</span> Chemical compound

Chromium(III) nitrate describes several inorganic compounds consisting of chromium, nitrate and varying amounts of water. Most common is the dark violet hygroscopic solid. An anhydrous green form is also known. Chromium(III) nitrate compounds are of a limited commercial importance, finding some applications in the dyeing industry. It is common in academic laboratories for the synthesis of chromium coordination complexes.

<span class="mw-page-title-main">Cobalt(II) sulfate</span> Inorganic compound

Cobalt(II) sulfate is any of the inorganic compounds with the formula CoSO4(H2O)x. Usually cobalt sulfate refers to the hexa- or heptahydrates CoSO4.6H2O or CoSO4.7H2O, respectively. The heptahydrate is a red solid that is soluble in water and methanol. Since cobalt(II) has an odd number of electrons, its salts are paramagnetic.

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

Chrome alum or Chromium(III) potassium sulfate is the potassium double sulfate of chromium. Its chemical formula is KCr(SO4)2 and it is commonly found in its dodecahydrate form as KCr(SO4)2·12(H2O). It is used in leather tanning.

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

Zirconium(IV) sulfate is the name for a family of inorganic salts with the formula Zr(SO4)2(H2O)n where n = 0, 4, 5, 7. These species are related by the degree of hydration. They are white or colourless solids that are soluble in water.

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

Chromium(II) sulfate is an inorganic compound with the chemical formula CrSO4. It often comes as hydrates CrSO4·nH2O. Several hydrated salts are known. The pentahydrate CrSO4·5H2O is a blue solid that dissolves readily in water. Solutions of chromium(II) are easily oxidized by air to Cr(III) species. Solutions of Cr(II) are used as specialized reducing agents of value in organic synthesis.

References

  1. 1 2 3 NIOSH Pocket Guide to Chemical Hazards. "#0141". National Institute for Occupational Safety and Health (NIOSH).
  2. Covington, A. D.; Lampard, G. S.; Menderes, O.; Chadwick, A. V.; Rafeletos, G.; O'Brien, P. "Extended X-ray absorption fine structure studies of the role of chromium in leather tanning" Polyhedron 2001, volume 20, 461–466. doi : 10.1016/S0277-5387(00)00611-2
  3. Riou, A.; Bonnin, A. (1982). "Structure de l'Hydroxysulfate de Chrome monohydrate". Acta Crystallographica B. 24 (5): 1968–38. doi: 10.1107/S0567740881005001 .
  4. 1 2 Gerd Anger; Jost Halstenberg; Klaus Hochgeschwender; Christoph Scherhag; Ulrich Korallus; Herbert Knopf; Peter Schmidt; Manfred Ohlinger. "Chromium Compounds". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a07_067. ISBN   978-3527306732.
  5. CW Harland; J Simpson. "Chromium sulfate tanning powder" (PDF). Farmers Fertiliser Ltd - a subsidiary of Fernz Corporation Ltd. Archived from the original (PDF) on 2018-01-27. Retrieved 2016-08-04.
  6. "Bentorite".
  7. "Redingtonite".
  8. "Putnisite".
  9. "List of Minerals". 21 March 2011.