| Revision as of 03:26, 11 August 2011 editCheMoBot (talk | contribs)Bots141,565 edits Updating {{chembox}} (no changed fields - added verified revid - updated 'DrugBank_Ref', 'ChEMBL_Ref') per Chem/Drugbox validation (report errors or [[use← Previous edit |
Latest revision as of 03:30, 10 June 2024 edit undoLindsey40186 (talk | contribs)Extended confirmed users8,182 editsm v2.05 - Fix errors for CW project (Ordinal number found inside <sup> tags)Tag: WPCleaner |
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{{chembox |
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{{Chembox |
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| Watchedfields = changed |
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| verifiedrevid = 443400721 |
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| verifiedrevid = 444189976 |
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| ImageFile = Arsenate.svg |
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| ImageFile = Arsenate.svg |
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| ImageSize = 150px |
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| ImageSize = 150px |
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| ImageAlt = Structural formula |
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| ImageName = Arsenic acid |
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| ImageFile1 = Arsenic-acid-3D-vdW.png |
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| ImageFile1 = Arsenic-acid-3D-balls.png |
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| ImageSize1 = 150px |
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| ImageSize1 = 150px |
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| ImageAlt1 = Ball-and-stick model |
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| ImageName1 = Arsenic acid |
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| IUPACName = Arsoric acid<ref>{{cite web | url=https://pubchem.ncbi.nlm.nih.gov/compound/234#section=IUPAC-Name&fullscreen=true | title=Arsenic acid }}</ref> |
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| IUPACName = Arsenic acid, arsoric acid |
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| OtherNames = Arsenic acid<br />Orthoarsenic acid<br />Desiccant L-10<br />Zotox |
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| OtherNames = {{ubl|Desiccant L-10|Orthoarsenic acid|Trihydrogen arsenate|Zotox}} |
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| Section1 = {{Chembox Identifiers |
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|Section1={{Chembox Identifiers |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID = 229 |
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| ChemSpiderID = 229 |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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| ChEBI_Ref = {{ebicite|correct|EBI}} |
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| ChEBI_Ref = {{ebicite|correct|EBI}} |
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| ChEBI = 18231 |
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| ChEBI = 18231 |
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| SMILES = O=(O)(O)O |
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| ChEMBL = 2374288 |
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| SMILES = O(O)()O |
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| InChIKey = DJHGAFSJWGLOIV-UHFFFAOYAY |
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| InChIKey = DJHGAFSJWGLOIV-UHFFFAOYAY |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey = DJHGAFSJWGLOIV-UHFFFAOYSA-N |
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| StdInChIKey = DJHGAFSJWGLOIV-UHFFFAOYSA-N |
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| CASNo = 7778-39-4 |
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| CASNo = 7778-39-4 |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| RTECS = CG0700000 |
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| RTECS = CG0700000 |
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| EINECS = 231-901-9 |
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}} |
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| PubChem = 234 |
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| Section2 = {{Chembox Properties |
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| UNNumber = 1553, 1554 |
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| Formula = H<sub>3</sub>AsO<sub>4</sub> |
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}} |
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| MolarMass = 141.94 g/mol |
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|Section2={{Chembox Properties |
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| Appearance = White translucent crystals,<br />]. |
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| Formula = {{chem2|H3AsO4}} |
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| Density = 2.5 g/cm<sup>3</sup> |
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| H=3|As=1|O=4 |
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| Solubility = 16.7 g/100 mL |
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| Appearance = White translucent or colorless crystals, ] |
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| SolubleOther = soluble in ] |
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| Density = 2.5 g/cm<sup>3</sup> |
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| MeltingPtC = 35.5 |
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| BoilingPt = decom ≥ 100 °C |
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| Solubility = 16.7 g/(100 mL) |
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| SolubleOther = soluble in ] |
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| pKa = 2.19, 6.94, 11.5 |
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| MeltingPtC = 35.5 |
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}} |
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| BoilingPtC = 120 |
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| Section3 = {{Chembox Structure |
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| BoilingPt_notes = decomposes |
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| MolShape = Tetrahedral |
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| ConjugateBase = ] |
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| CrystalStruct = |
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| pKa = p''K''<sub>a1</sub> = 2.19<br>p''K''<sub>a2</sub> = 6.94<br>p''K''<sub>a3</sub> = 11.5<ref name=P82db>{{cite book|title=Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution|editor-first=D. D.|editor-last=Perrin|edition=2nd|series=] Chemical Data|issue=29|publisher=Pergamon|location=Oxford|year=1982|publication-date=1984|orig-date=1969|lccn=82-16524|isbn=0-08-029214-3|at=Entry 11}}</ref> |
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}} |
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| VaporPressure = 55 hPa (50 °C) |
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| Section7 = {{Chembox Hazards |
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}} |
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| ExternalMSDS = |
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|Section3={{Chembox Structure |
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| EUClass = Toxic ('''T''')<br/>Dangerous for the environment ('''N''') <!-- Index No. 033-005-00-1 --> |
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| MolShape = ] at ] atom |
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| FlashPt = Non-flammable |
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| CrystalStruct = |
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| RPhrases = {{R23/25}}, {{R45}}, {{R50/53}} |
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}} |
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| SPhrases = {{S53}}, {{S45}}, {{S60}}, {{S61}} |
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|Section7={{Chembox Hazards |
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| NFPA-H = 3 |
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| MainHazards = Extremely toxic, carcinogenic, corrosive |
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| NFPA-F = 0 |
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| NFPA-R = 0 |
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| ExternalSDS = |
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| FlashPt = Non-flammable |
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}} |
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| GHSPictograms = {{GHS05}}{{GHS06}}{{GHS07}}{{GHS08}}{{GHS09}} |
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| Section8 = {{Chembox Related |
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| GHSSignalWord = Danger |
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| OtherAnions = ] |
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| HPhrases = {{H-phrases|301|312|314|331|350|361|410}} |
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| OtherCations = ] |
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| PPhrases = {{P-phrases|201|202|260|261|264|270|271|273|280|281|301+310|301+330+331|302+352|303+361+353|304+340|305+351+338|308+313|310|311|312|321|322|330|363|391|403+233|405|501}} |
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| OtherCpds = ]<br />] |
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| NFPA-H = 4 |
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}} |
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| NFPA-F = 0 |
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| NFPA-R = 0 |
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| LD50 = 48 mg/kg (rat, oral) |
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6 mg/kg (rabbit, oral) |
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}} |
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|Section8={{Chembox Related |
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| OtherCations = ] |
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| OtherCompounds = {{ubl|]|]|]}} |
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}} |
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]: impure, pure and distilled.]] |
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'''Arsenic acid''' is the ] with the ] H<sub>3</sub>AsO<sub>4</sub>. More descriptively written as AsO(OH)<sub>3</sub>, this colorless ] is the ] analogue of ]. Arsenate and phosphate salts behave very similarly. Arsenic acid as such has not been isolated, but only found in solution where it is largely ionized. Its hemihydrate form (H<sub>3</sub>AsO<sub>4</sub>·½H<sub>2</sub>O) does form stable crystals. Crystalline samples dehydrate with condensation at 100 °C.<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.</ref> |
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'''Arsenic acid''' or '''arsoric acid''' is the ] with the ] {{chem2|H3AsO4}}. More descriptively written as {{chem2|AsO(OH)3}}, this colorless ] is the ] analogue of ]. ] and ] salts behave very similarly. Arsenic acid as such has not been isolated, but is only found in solution, where it is largely ionized. Its ] form ({{chem2|2H3AsO4*H2O}}) does form stable crystals. Crystalline samples dehydrate with condensation at 100 °C.<ref>{{ cite book |author1=Holleman, A. F. |author2=Wiberg, E. | title = Inorganic Chemistry | publisher = Academic Press | location = San Diego | year = 2001 | isbn = 0-12-352651-5 }}</ref> |
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==Properties== |
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==Properties== |
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It is a tetrahedral species of idealized ] C<sub>3v</sub> with As-O bonds lengths ranging from 1.66 to 1.71 Å.<!--the terminal As=O is not so clear due to H-bonding--><ref>{{cite journal | author = Lee, C.; Harrison, W. T. A. | title = Tetraethylammonium dihydrogenarsenate bis(arsenic acid) and 1,4-diazoniabicyclooctane bis(dihydrogenarsenate) arsenic acid: hydrogen-bonded networks containing dihydrogenarsenate anions and neutral arsenic acid molecules | journal = ] | year = 2007 | volume = C63 | pages = m308-m311 | doi=10.1107/S0108270107023967 | pmid = 17609552 | issue = Pt 7}}</ref> |
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It is a tetrahedral species of idealized ] ''C''<sub>3v</sub> with As–O bond lengths ranging from 1.66 to 1.71 Å.<!--the terminal As=O is not so clear due to H-bonding--><ref>{{cite journal |author1=Lee, C. |author2=Harrison, W. T. A. | title = Tetraethylammonium dihydrogenarsenate bis(arsenic acid) and 1,4-diazoniabicyclooctane bis(dihydrogenarsenate) arsenic acid: hydrogen-bonded networks containing dihydrogenarsenate anions and neutral arsenic acid molecules | journal = ] | year = 2007 | volume = 63 | issue = Pt 7 | pages = m308–m311 | doi = 10.1107/S0108270107023967 | pmid = 17609552 }}</ref> |
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Being a triprotic ], its acidity is described by three equilibria: |
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Being a ] acid, its acidity is described by three equilibria: |
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:{{chem2|H3AsO4 + H2O ⇌ H2AsO4- + +}}, p''K''<sub>a1</sub> = 2.19 |
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:H<sub>3</sub>AsO<sub>4</sub> {{eqm}} H<sub>2</sub>AsO{{su|b=4|p=−}} + H<sup>+</sup> (K<sub>1</sub> = 10<sup>−2.19</sup>) |
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:H<sub>2</sub>AsO{{su|b=4|p=−}} {{eqm}} HAsO{{su|b=4|p=2−}} + H<sup>+</sup> (K<sub>2</sub> = 10<sup>−6.94</sup>) |
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:{{chem2|H2AsO4- + H2O ⇌ HAsO4(2-) + +}}, p''K''<sub>a2</sub> = 6.94 |
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:HAsO{{su|b=4|p=2−}} {{eqm}} AsO{{su|b=4|p=3−}} + H<sup>+</sup> (K<sub>3</sub> = 10<sup>−11.5</sup>) |
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:{{chem2|HAsO4(2-) + H2O ⇌ AsO4(3-) + +}}, p''K''<sub>a3</sub> = 11.5 |
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These K<sub>a</sub> values are close to those for phosphoric acid. The highly basic ] (AsO{{su|b=4|p=3−}}) is the product of the third ionization. Unlike phosphoric acid, arsenic acid is oxidizing, illustrated by its ability to convert ] to ]. |
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These ] values are close to those for ]. The highly basic ] ({{chem|AsO|4|3-}}) is the product of the third ionization. Unlike phosphoric acid, arsenic acid is an oxidizer, as illustrated by its ability to convert ] to ]. |
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==Preparation== |
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==Preparation== |
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Arsenic acid is prepared by treating arsenic trioxide with concentrated ], or by combination of ] with water. The latter reaction is very slow. It is also formed when meta- or ] is treated with cold water. |
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Arsenic acid is prepared by treating arsenic trioxide with concentrated ]. ] is produced as a by-product.<ref name=Brauer>{{ cite book | chapter = Arsenic Acid | title = Handbook of Preparative Inorganic Chemistry | edition = 2nd | editor = G. Brauer | publisher = Academic Press | year = 1963 | location = New York | volume = 1 | page = 601 }}</ref> |
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:{{chem2|As2O3 + 2 HNO3 + 2 H2O → 2 H3AsO4 + N2O3}} |
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The resulting solution is cooled to give colourless crystals of the ] {{chem2|H3AsO4*0.5H2O}} (or {{chem2|2H3AsO4*H2O}}), although the dihydrate {{chem2|H3AsO4*2H2O}} is produced when crystallisation occurs at lower temperatures.<ref name=Brauer/> |
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==Other methods== |
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===Other methods=== |
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Arsenic acid can be prepared by reacting moist elemental arsenic with ]. |
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Arsenic acid is slowly formed when ] is dissolved in water, and when ''meta''- or ] ({{chem2|H4As2O7}}) is treated with cold water. Arsenic acid can also be prepared directly from elemental arsenic by moistening it and treating with ]. |
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:{{chem2|2 As + 3 H2O + 5 O3 → 2 H3AsO4 + 5 O2}} |
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: 2As + 3H<sub>2</sub>O + 5O<sub>3</sub> → 2H<sub>3</sub>AsO<sub>4</sub> + 5O<sub>2</sub> |
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==Applications== |
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==Applications== |
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Commercial applications of arsenic acid are limited by its toxicity. It has found occasional use as a ], broad-spectrum biocide, a finishing agent for glass and metal, and a ] in the synthesis of some ]s and organic arsenic compounds. The {{LD50}} in rabbits is 6 mg/kg (0.006 g/kg).<ref>Joachimoglu. ''Biochem. Z.'' '''70''', 144 (1915)</ref> |
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Commercial applications of arsenic acid are limited by its toxicity. It is a precursor to a variety of pesticides. It has found occasional use as a ], a broad-spectrum ], a finishing agent for glass and metal, and a ] in the synthesis of some ]s and organic arsenic compounds.<ref name="MY2008">{{cite book|title=Minerals Yearbook, 2008, V. 1, Metals and Minerals|url=https://books.google.com/books?id=tL4hau707bwC&pg=SA6-PA10|year=2010|publisher=Government Printing Office|isbn=978-1-4113-3015-3|pages=6–}}</ref> |
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==Safety== |
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Arsenic acid is extremely toxic and carcinogenic, like all arsenic compounds. It is also ]. The {{LD50}} in rabbits is 6 mg/kg (0.006 g/kg).<ref name="GrundHanusch2008">{{cite book|last1=Grund|first1=Sabina C.|title=Ullmann's Encyclopedia of Industrial Chemistry|last2=Hanusch|first2=Kunibert|last3=Wolf|first3=Hans Uwe|chapter=Arsenic and Arsenic Compounds|year=2008|doi=10.1002/14356007.a03_113.pub2|isbn=978-3527306732}}</ref> |
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==References== |
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==References== |
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{{Hydrogen compounds}} |
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