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Latest revision as of 00:06, 23 November 2024 edit undoFirefoxRelayMask (talk | contribs)42 editsm Balanced the CaSO4 chemical formula |
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{{chembox |
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| Verifiedfields = changed |
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| verifiedrevid = 396307496 |
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| verifiedrevid = 433612289 |
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|ImageFile=Calcium sulfite.png |
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|ImageSize=120px |
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| ImageSize=240px |
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| ImageFile=CaSO3.svg |
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|IUPACName=Calcium sulfite |
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| IUPACName=Calcium sulfite |
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|OtherNames=Sulfurous acid, calcium salt (1:1)<br/>E226 |
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| OtherNames={{Unbulleted list|Sulfurous acid, calcium salt (1:1)|E226}} |
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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 = 8329549 |
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| ChemSpiderID = 8329549 |
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| InChI = 1/Ca.H2O3S/c;1-4(2)3/h;(H2,1,2,3)/q+2;/p-2 |
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| InChI = 1/Ca.H2O3S/c;1-4(2)3/h;(H2,1,2,3)/q+2;/p-2 |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChI = 1S/Ca.H2O3S/c;1-4(2)3/h;(H2,1,2,3)/q+2;/p-2 |
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| StdInChI = 1S/Ca.H2O3S/c;1-4(2)3/h;(H2,1,2,3)/q+2;/p-2 |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}} |
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| StdInChIKey = GBAOBIBJACZTNA-UHFFFAOYSA-L |
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| StdInChIKey = |
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| CASNo = 10257-55-3 |
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| CASNo = 10257-55-3 |
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| CASNo_Comment = (anhydrous) |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| PubChem = 159274 |
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| CASNo2 = 72878-03-6 |
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| CASNo2_Comment = (tetrahydrate) |
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| CASNo3 = 29501-28-8 |
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| CASNo3_Comment = (hemihydrate) |
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| UNII_Ref = {{fdacite|changed|FDA}} |
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| UNII = 7078964UQP |
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| PubChem = 10154041 |
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| EC_number = 233-596-8 |
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|Section2= {{Chembox Properties |
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|Section2={{Chembox Properties |
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| Formula = CaSO<sub>3</sub> |
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| Formula = CaSO<sub>3</sub> |
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| MolarMass = 120.17 g/mol |
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| MolarMass = 120.17{{nbsp}}g/mol |
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| Appearance = |
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| Appearance = White solid |
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| Density = |
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| MeltingPtC = 600 |
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| MeltingPtC = 600 |
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| BoilingPt = |
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| Solubility = 4.3{{nbsp}}mg/100{{thinsp}}mL (18{{nbsp}}°C) |
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| BoilingPt = |
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| SolubilityProduct =3.1{{e|−7}}<ref name="crc">{{cite book |author1=John Rumble |title=CRC Handbook of Chemistry and Physics |date=June 18, 2018 |publisher=CRC Press |isbn=978-1138561632 |pages=5–188|edition=99 |language=English}}</ref> |
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| Solubility = 0.0043 g/100 mL, 18C |
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|Section3= {{Chembox Hazards |
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| External MSDS = |
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| FlashPt = Non-flammable |
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| EUIndex = Not listed |
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| FlashPt = Non-flammable |
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| Section8 = {{Chembox Related |
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|Section8={{Chembox Related |
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| OtherAnions = ] |
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| OtherAnions = ] |
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| OtherCations = ] |
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'''Calcium sulfite''', or '''calcium sulphite''', is a chemical compound, the ] of ] with the formula CaSO<sub>3</sub>·x(H<sub>2</sub>O). Two crystalline forms are known, the hemihydrate and the tetrahydrate, respectively CaSO<sub>3</sub>·½(H<sub>2</sub>O) and CaSO<sub>3</sub>·4(H<sub>2</sub>O).<ref name=Xray>{{cite journal|journal=Chemistry Letters|volume=13|issue=7|pages=1051–1054|year= 1984|doi=10.1246/cl.1984.1051|title=Studies On Alkaline Earth Sulfites. Structure and Stability of the New Compound Ca<sub>3</sub>(SO<sub>3</sub>)<sub>2</sub>SO<sub>4</sub><sup>.</sup>12H<sub>2</sub>O and Its Solid Solution In Calcium Sulfite Tetrahydrate|author1=Abraham Cohen|author2=Mendel Zangen|doi-access=free}}</ref> All forms are white solids. It is most notable as the product of ]. |
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'''Calcium sulfite''', or '''calcium sulphite''', is a chemical compound which is the ] ] of ] with the molecular formula CaSO<sub>3</sub>. As a ] it is used as a ] under the ] E226. It is commonly used in preserving wine, cider, fruit juice, canned fruit and vegetables. |
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== Production == |
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Like other metal sulfites, calcium sulfite reacts with acids to produce a calcium salt, ] gas and water. For this reason, CaSO<sub>3</sub> is not a desirable compound in drywall - when humid (with the natural acidity of carbon dioxide found in the air), it releases sulfur dioxide and ] is absorbed to form ]. |
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{{Main article|Flue-gas desulfurization}} |
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It is produced on a large scale by flue gas ] (FGD). When coal or other fossil fuel is burned, the byproduct is known as ]. Flue gas often contains SO<sub>2</sub>, whose emission is often regulated to prevent ]. Sulfur dioxide is scrubbed before the remaining gases are emitted through the ] stack. An economical way of scrubbing SO<sub>2</sub> from flue gases is by treating the effluent with Ca(OH)<sub>2</sub> ] or CaCO<sub>3</sub> ].<ref>{{Ullmann|doi=10.1002/14356007.a04_555|isbn=3527306730|title=Calcium Sulfate|year=2000|last1=Wirsching|first1=Franz}}</ref> |
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Scrubbing with limestone follows the following idealized reaction: |
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: {{chem2|SO2}} + {{chem2|CaCO3}} → {{chem2|CaSO3}} + {{chem2|CO2}} |
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Scrubbing with hydrated lime follows the following idealized reaction:<ref>{{Cite book|title = Sulfur Oxidation in Scrubber Systems|last = Hudson|first = JL|publisher = University of Virginia|year = 1980}}</ref><ref>{{Cite book|title = Coal Energy Systems|last = Miller|first = Bruce|publisher = Elsevier Science Technology|year = 2004|pages = 294–299}}</ref> |
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: {{chem2|SO2}} + {{chem2|Ca(OH)2}} → {{chem2|CaSO3}} + {{chem2|H2O}} |
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The resulting calcium sulfite oxidizes in air to give gypsum: |
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: 2 {{chem2|CaSO3}} + {{chem2|O2}} → 2 {{chem2|CaSO4}} |
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The gypsum, if sufficiently pure, is marketable as a building material. |
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== Uses == |
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=== Drywall === |
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Calcium sulfite is generated as the intermediate in the production of gypsum, which is the main component of ]. A typical US home contains 7 metric tons of such drywall gypsum board.<ref>{{Cite web|url=http://minerals.usgs.gov/minerals/pubs/commodity/gypsum/|title=USGS Gypsum Statistics and Information|website=USGS|access-date=June 26, 2016}}</ref> |
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=== Food additive === |
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As a food additive it is used as a preservative under the E number E226. Along with other antioxidant ], it is commonly used in preserving wine, cider, fruit juice, canned fruit and vegetables. Sulfites are strong reducers in solution, they act as ] ] to preserve food, but labeling is required as some individuals might be ]. |
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=== Wood pulp production === |
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Chemical wood pulping is the removal of cellulose from wood by dissolving the lignin that binds the cellulose together. Calcium sulfite can be used in the production of wood pulp through the ], as an alternative to the ] that uses hydroxides and ] instead of sulfites. Calcium sulfite was used, but has been largely replaced by magnesium and sodium sulfites and bisulfites to attack the lignin.{{cn|date=September 2023}} |
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=== Gypsum === |
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There is a possibility to use calcium sulfite to produce ] by oxidizing (adding ]) it in water mixture with the manganese (]) cation or ] ].<ref>{{Cite journal|last1=Li|first1=Yuran|last2=Zhou|first2=Jinting|last3=Zhu|first3=Tingyu|last4=Jing|first4=Pengfei|date=2014-02-01|title=Calcium Sulfite Oxidation and Crystal Growth in the Process of Calcium Carbide Residue to Produce Gypsum|journal=Waste and Biomass Valorization|language=en|volume=5|issue=1|pages=125–131|doi=10.1007/s12649-013-9206-2|bibcode=2014WBioV...5..125L |s2cid=98774317|issn=1877-2641}}</ref><ref>{{Cite web|url=https://www.researchgate.net/post/How_can_we_convert_calcium_sulfite_into_calcium_sulfate_after_a_flue_gas_desulfurization_scrubber|title=How can we convert calcium sulfite into calcium sulfate after...|website=ResearchGate|language=en|access-date=2018-05-18}}</ref> |
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==Structure== |
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<gallery mode=packed> |
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Ca3(SO3)2aq12.png|Structure of the <sup>2+</sup> cage in calcium sulfite tetrahydrate. |
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CaSO30.5aq.png|Structure of anhydrous CaSO<sub>3</sub>. |
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</gallery> |
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] shows that anhydrous calcium sulfite has a complicated polymeric structure.<ref>{{cite journal|title=Crystal Structure of Calcium Sulfite|author1=Yasue, Tamotsu |author2=Arai, Yasuo |journal=Gypsum & Lime (Jap. Language)|year=1986|volume=203|pages=235–44}}</ref> The tetrahydrate crystallizes as a solid solution of Ca<sub>3</sub>(SO<sub>3</sub>)2(SO<sub>4</sub>)<sup>.</sup>12H<sub>2</sub>O and Ca<sub>3</sub>(SO<sub>3</sub>)2(SO<sub>3</sub>)<sup>.</sup>12H<sub>2</sub>O. The ] represents an intermediate in the oxidation of the sulfite to the sulfate, as is practiced in the production of ]. This solid solution consists of <sup>2+</sup> cations and either sulfite or sulfate as the anion.<ref name=Xray/><ref>{{cite journal|title=The Crystal Structure of Calcium Sulfite Hemihydrate|author1=Matsuno, Takashi |author2=Takayanagi, Hiroaki |author3=Furuhata, Kimio |author4=Koishi, Masumi |author5=Ogura, Haruo |journal= Bulletin of the Chemical Society of Japan|year=1984|volume=57|issue=4|pages=1155–6|doi=10.1246/bcsj.57.1155|doi-access=free}}</ref> These crystallographic studies confirm that sulfite anion adopts a pyramidal geometry. |
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==Natural occurrence== |
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Calcium sulfite(III) hemihydrate occurs in the nature as the rare mineral hannebachite.<ref>{{Cite web|url=https://www.mindat.org/min-1997.html|title=Hannebachite}}</ref><ref>{{Cite web|url=https://www.ima-mineralogy.org/Minlist.htm|title=List of Minerals|date=21 March 2011}}</ref> |
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== See also == |
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* ] |
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* ] |
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* ] |
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* ] |
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* ] |
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* ] |
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==References== |
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{{reflist}} |
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{{Calcium compounds}} |
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{{Calcium compounds}} |
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{{Sulfites}} |
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{{inorganic-compound-stub}} |
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