Calcium arsenate

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Calcium arsenate
Calciumarsenaat.png
Arsenian Wapnia.jpg
Names
IUPAC name
Calcium arsorate
Other names
Calcium orthoarsenate
Cucumber dust
Tricalcium arsenate
Tricalcium ortho-arsenate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.003 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 233-287-8
KEGG
PubChem CID
RTECS number
  • CG0830000
UNII
  • InChI=1S/2AsH3O4.3Ca/c2*2-1(3,4)5;;;/h2*(H3,2,3,4,5);;;/q;;3*+2/p-6 X mark.svgN
    Key: RMBBSOLAGVEUSI-UHFFFAOYSA-H X mark.svgN
  • InChI=1/2AsH3O4.3Ca/c2*2-1(3,4)5;;;/h2*(H3,2,3,4,5);;;/q;;3*+2/p-6
    Key: RMBBSOLAGVEUSI-CYFPFDDLAC
  • [O-][As](=O)([O-])[O-].[O-][As](=O)([O-])[O-].[Ca+2].[Ca+2].[Ca+2]
Properties
Ca3(AsO4)2
Molar mass 398.072 g/mol
Appearancewhite powder
Odor odorless
Density 3.62 g/cm3, solid
Melting point 1,455 °C (2,651 °F; 1,728 K) (decomposes)
0.013 g/100 mL (25 °C) [1]
Solubility in Organic solvents insoluble
Solubility in acids soluble
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 carcinogen [2]
NFPA 704 (fire diamond)
NFPA 704.svgHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 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
4
0
0
Flash point noncombustible [2]
Lethal dose or concentration (LD, LC):
20 mg/kg (rat, oral)
82 mg/kg (rat, oral)
74 mg/kg (mouse, oral)
50 mg/kg (rabbit, oral)
38 mg/kg (dog, oral) [3]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 0.010 mg/m3 [2]
REL (Recommended)
Ca C 0.002 mg/m3 [15-minute] [2]
IDLH (Immediate danger)
5 mg/m3 (as As) [2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Calcium arsenate is the inorganic compound with the formula Ca3(AsO4)2. A colourless salt, it was originally used as a pesticide and as a germicide. It is highly soluble in water, in contrast to lead arsenate, which makes it more toxic. Two minerals are hydrates of calcium arsenate: rauenthalite Ca3(AsO4)2·10H2O and phaunouxite Ca3(AsO4)2·11H2O. [4] A related mineral is ferrarisite (Ca5H2(AsO4)4·9H2O. [5]

Preparation

Calcium arsenate is commonly prepared from disodium hydrogen arsenate and calcium chloride:

2 Na2H[AsO4] + 3 CaCl2 → 4 NaCl + Ca3[AsO4]2 + 2 HCl

In the 1920s, it was made in large vats by mixing calcium oxide and arsenic oxide. [6] In the United States, 1360 metric tons were produced in 1919, 4540 in 1920, and 7270 in 1922. [1] The composition of commercially available calcium arsenate varies from manufacturer to manufacturer. A typical composition is 80-85% of Ca3(AsO4)2 a basic arsenate probably with a composition of 4CaO.As2O5 together with calcium hydroxide and calcium carbonate.[ citation needed ]

Use as a herbicide

It was once a common herbicide and insecticide. 38,000,000 kilograms were reported to be produced in 1942 alone, mainly for protection of cotton crops. Its high toxicity led the development of DDT. [7]

Regulation

Calcium arsenate use is now banned in the UK, and its use is strictly regulated in the United States. It is currently the active ingredient in TURF-Cal manufactured by Mallinckrodt, it is one of the few herbicides – used mainly for the control of Poa annua and crabgrass- that hinders earthworm activity. Its label states that it will "reduce and inhibit earthworm activity and survival" and is only recommended against serious earthworm infestations in places such as golf course greens. [8]

Toxicity and regulation

Calcium arsenate is highly toxic, having both carcinogenic and systemic health effects. [9] The Occupational Safety and Health Administration has set a permissible exposure limit at 0.01 mg/m3 over an eight-hour time-weighted average, while the National Institute for Occupational Safety and Health recommends a limit five times less (0.002 mg/m3). [10]

It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities. [11]

Other natural occurrences

Weilite is the monohydrogenated counterpart, Ca(HAsO4), [12] while švenekite – the dihydrogenated one, Ca(H2AsO4)2. [13] Hydrated analogues of weilite are haidingerite (monohydrate) and pharmacolite (dihydrate), with the latter name reflecting arsenic-related toxicity. Examples of more complex, hydrated Ca arsenates with some anions hydrogenated, are ferrarisite, [14] guérinite, [15] sainfeldite, [16] vladimirite, [17] and jeankempite. [18] [19]

Related Research Articles

<span class="mw-page-title-main">Arsenic</span> Chemical element, symbol As and atomic number 33

Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but only the grey form, which has a metallic appearance, is important to industry.

<span class="mw-page-title-main">Mineral wool</span> Fiber made from spun molten minerals

Mineral wool is any fibrous material formed by spinning or drawing molten mineral or rock materials such as slag and ceramics.

<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">Bromoform</span> Chemical compound

Bromoform is an organic compound with the chemical formula CHBr3. It is a colorless liquid at room temperature, with a high refractive index and a very high density. Its sweet odor is similar to that of chloroform. It is one of the four haloforms, the others being fluoroform, chloroform, and iodoform. It is a brominated organic solvent. Currently its main use is as a laboratory reagent. It is very slightly soluble in water and is miscible with alcohol, benzene, chloroform, ether, petroleum ether, acetone and oils.

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

Benomyl is a fungicide introduced in 1968 by DuPont. It is a systemic benzimidazole fungicide that is selectively toxic to microorganisms and invertebrates, especially earthworms, but nontoxic toward mammals.

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

Antimony(III) oxide is the inorganic compound with the formula Sb2O3. It is the most important commercial compound of antimony. It is found in nature as the minerals valentinite and senarmontite. Like most polymeric oxides, Sb2O3 dissolves in aqueous solutions with hydrolysis. A mixed arsenic-antimony oxide occurs in nature as the very rare mineral stibioclaudetite.

<span class="mw-page-title-main">Lead hydrogen arsenate</span> Chemical compound

Lead hydrogen arsenate, also called lead arsenate, acid lead arsenate or LA, chemical formula PbHAsO4, is an inorganic insecticide used primarily against the potato beetle. Lead arsenate was the most extensively used arsenical insecticide. Two principal formulations of lead arsenate were marketed: basic lead arsenate (Pb5OH(AsO4)3, CASN: 1327-31-7) and acid lead arsenate (PbHAsO4).

The arsenate is an ion with the chemical formula AsO3−4. Bonding in arsenate consists of a central arsenic atom, with oxidation state +5, double bonded to one oxygen atom and single bonded to a further three oxygen atoms. The four oxygen atoms orient around the arsenic atom in a tetrahedral geometry. Resonance disperses the ion's −3 charge across all four oxygen atoms.

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

Arsenic acid or arsoric acid is the chemical compound with the formula H3AsO4. More descriptively written as AsO(OH)3, this colorless acid is the arsenic analogue of phosphoric acid. Arsenate and phosphate salts behave very similarly. Arsenic acid as such has not been isolated, but is only found in solution, where it is largely ionized. Its hemihydrate form (2H3AsO4·H2O) does form stable crystals. Crystalline samples dehydrate with condensation at 100 °C.

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

Arsenous acid (or arsenious acid) is the inorganic compound with the formula H3AsO3. It is known to occur in aqueous solutions, but it has not been isolated as a pure material, although this fact does not detract from the significance of As(OH)3.

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

Arsenic pentoxide is the inorganic compound with the formula As2O5. This glassy, white, deliquescent solid is relatively unstable, consistent with the rarity of the As(V) oxidation state. More common, and far more important commercially, is arsenic(III) oxide (As2O3). All inorganic arsenic compounds are highly toxic and thus find only limited commercial applications.

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

Copper arsenate (Cu3(AsO4)2·4H2O, or Cu5H2(AsO4)4·2H2O), also called copper orthoarsenate, tricopper arsenate, cupric arsenate, or tricopper orthoarsenate, is a blue or bluish-green powder insoluble in water and alcohol and soluble in aqueous ammonium and dilute acids. Its CAS number is 7778-41-8 or 10103-61-4.

<span class="mw-page-title-main">Monosodium methyl arsonate</span> Arsenic-based herbicide

Monosodium methyl arsenate (MSMA) is an arsenic-based herbicide. It is an organo-arsenate; less toxic than the inorganic form of arsenates. However, the EPA states that all forms of arsenic are a serious risk to human health and the United States' Agency for Toxic Substances and Disease Registry ranked arsenic as number 1 in its 2001 Priority List of Hazardous Substances at Superfund sites.

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

Arsenic trichloride is an inorganic compound with the formula AsCl3, also known as arsenous chloride or butter of arsenic. This poisonous oil is colourless, although impure samples may appear yellow. It is an intermediate in the manufacture of organoarsenic compounds.

Potassium arsenite (KAsO2) is an inorganic compound that exists in two forms, potassium meta-arsenite (KAsO2) and potassium ortho-arsenite (K3AsO3). It is composed of arsenite ions (AsO33− or AsO2−) with arsenic always existing in the +3 oxidation state. Like many other arsenic containing compounds, potassium arsenite is highly toxic and carcinogenic to humans. Potassium arsenite forms the basis of Fowler’s solution, which was historically used as a medicinal tonic, but due to its toxic nature its use was discontinued. Potassium arsenite is still, however, used as a rodenticide.

<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.

<span class="mw-page-title-main">Disodium methyl arsonate</span> Chemical compound

Disodium methyl arsonate (DSMA) is the organoarsenic compound with the formula CH3AsO3Na2. It is a colorless, water-soluble solid derived from methanearsonic acid. It is used as a herbicide. Tradenames include Metharsinat, Arrhenal, Disomear, Metharsan, Stenosine, Tonarsan, Tonarsin, Arsinyl, Arsynal, and Diarsen.

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

Picropharmacolite, Ca4Mg(AsO3OH)2(AsO4)2·11H2O, is a rare arsenate mineral. It was named in 1819 from the Greek for bitter, in allusion to its magnesium content, and its chemical similarity to pharmacolite. The mineral irhtemite, Ca4Mg(AsO3OH)2(AsO4)2·4H2O, has the same composition as picropharmacolite, except that it has only four water molecules per formula unit, instead of eleven. It may be formed by the dehydration of picropharmacolite.

Ammonium orthomolybdate is the inorganic compound with the chemical formula (NH4)2MoO4. It is a white solid that is prepared by treating molybdenum trioxide with aqueous ammonia. Upon heating these solutions, ammonia is lost, to give ammonium heptamolybdate ((NH4)6Mo7O24·4H2O).

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

Pentachloroethane is a chemical compound of chlorine, hydrogen, and carbon with the chemical formula C2HCl5. It is colourless non-flammable liquid that is used as a solvent for oil and grease, in metal cleaning, and in the separation of coal from impurities.

References

  1. 1 2 Tartar, H.V.; Wood, L; Hiner, E; A Basic Arsenate of Calcium. J. Am. Chem. Soc. 1924, vol. 46, 809-813.
  2. 1 2 3 4 5 NIOSH Pocket Guide to Chemical Hazards. "#0089". National Institute for Occupational Safety and Health (NIOSH).
  3. ↑ "Calcium arsenate (as As)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. ↑ Bari, Hubert; Catti, Michele; Ferraris, Giovanni; Ivaldi, Gabriella; Permingeat, François (1982). "Phaunouxite Ca3(AsO4)2•11H2O, a New Mineral Strictly Associated with Rauenthalite". Bulletin de Minéralogie. 105 (4): 327–332. doi:10.3406/bulmi.1982.7624.
  5. ↑ Bari, Hubert; Permingeat, François; Pierrot, Roland; Walenta, Kurt (1980). "La ferrarisite Ca5H2(AsO4)4.9 H2O, une Nouvelle Espèce Minérale Dimorphe de la Guérinite". Bulletin de Minéralogie. 103 (5): 533–540. doi:10.3406/bulmi.1980.7417.
  6. ↑ Smith, C.M.; Murray, C.W.; The Composition of Commercial Calcium Arsenate. Journal of Industrial and Engineering Chemistry; 1931, 23
  7. ↑ Robert L. Metcalf "Insect Control" in Ullmann’s Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2002. doi : 10.1002/14356007.a14_263
  8. ↑ Koval, C.F. "Turf insect pest control guide: Urban Phytonarian Series" (PDF). College of Agricultural and Life Sciences – University of Wisconsin-Madison. Retrieved 9 November 2018.
  9. ↑ Tchounwou, P.B.; Patlolla, A.K.; Centeno, J.A.; Carcinogenic and Systematic Health Effects Associated with Arsenic – A Critical Review. Toxicologic Pathology; 2003, 31, 575-588
  10. ↑ "Calcium Arsenate". NIOSH Pocket Guide to Chemical Hazards. Centers for Disease Control and Prevention. 4 April 2011. Retrieved 18 November 2013.
  11. ↑ "40 C.F.R.: Appendix A to Part 355—The List of Extremely Hazardous Substances and Their Threshold Planning Quantities" (PDF) (1 July 2008 ed.). Government Printing Office. Archived from the original (PDF) on 25 February 2012. Retrieved 29 October 2011.{{cite journal}}: Cite journal requires |journal= (help)
  12. ↑ "Weilite".
  13. ↑ "Švenekite".
  14. ↑ "Ferrarisite".
  15. ↑ "Guérinite".
  16. ↑ "Sainfeldite".
  17. ↑ "Vladimirite".
  18. ↑ "Jeankempite".
  19. ↑ "List of Minerals". 21 March 2011.
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