Sulfat de calci: diferència entre les revisions
Contingut suprimit Contingut afegit
mCap resum de modificació |
Cap resum de modificació |
||
Línia 1:
{{100}}
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 443496462
| Name = Sulfat de calci
| ImageFile = Calcium sulfate hemihydrate.jpg
| ImageSize =
| ImageName = Sulfat de calci hemihidratat
| OtherNames = [[Guix]]<br>Guix de Paris o [[Escaiola (construcció)|escaiola]]
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 22905
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = E934B3V59H
| InChI = 1/Ca.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 31346
| SMILES = [Ca+2].[O-]S([O-])(=O)=O
| InChIKey = OSGAYBCDTDRGGQ-NUQVWONBAU
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/Ca.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = OSGAYBCDTDRGGQ-UHFFFAOYSA-L
| CASNo = 7778-18-9
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo2_Ref = {{cascite|changed|??}}
| CASNo2 = 10034-76-1
| CASNo2_Comment = (hemihidrat)
| CASNo3_Ref = {{cascite|changed|??}}
| CASNo3 = 10101-41-4
| CASNo3_Comment = (dihidrat)
| PubChem = 24928
| RTECS = WS6920000
| KEGG_Ref = {{keggcite|changed|kegg}}
| KEGG = D09201
}}
|Section2={{Chembox Properties
| Density = 2,96 g/cm<sup>3</sup> (anhidre) <br> 2,32 g/cm<sup>3</sup> (dihidrat)
| Solubility = 0,21g/100ml at 20 °C (anhidre)<ref>{{cite book|url=http://books.google.com/books?id=s4YittJrOsAC&pg=PA71|page=71|title=The Dictionary of Substances and Their Effects: C|author= S. Gangolli|publisher=Royal Society of Chemistry|year=1999|isbn=0-85404-813-8}}</ref> <br/> 0,24 g/100ml at 20 °C (dihidrat)<ref>{{cite book|url=http://books.google.com/books?id=JXO-HdRnTl0C&pg=PA242|page=242|title=Reagent chemicals: specifications and procedures : American Chemical Society specifications, official from January 1, 2006|author=American Chemical Society|publisher=Oxford University Press|year=2006|isbn=0-8412-3945-2}}</ref>
| Solvent = [[glicerol]]
| SolubleOther = lleugerament soluble (dihidrat)
| SolubilityProduct = 4,93 × 10<sup>−5</sup> mol<sup>2</sup>L<sup>−2</sup> (anhidre)<br> 3,14 × 10<sup>−5</sup> (hemihidrat)<br> <ref>D.R. Linde (ed.) "CRC Handbook of Chemistry and Physics", 83rd Edition, CRC Press, 2002</ref>
| MeltingPtC = 1460
| MeltingPt_notes = (anhidre)
| Formula = CaSO<sub>4</sub>
| MolarMass = 136,14 g/mol (anhidre)<br/>145,15 g/mol (hemihidrat) <br> 172,172 g/mol (dihidrat)
| Appearance = Sòlid blanc
| Odor = Sense olor
| pKa = 10,4 (anhidre) <br> 7,3 (dihidrat)
}}
|Section3={{Chembox Structure
| Coordination =
| CrystalStruct = [[Ortoròmbic]]
}}
|Section4={{Chembox Thermochemistry
| DeltaHf = -1433 kJ/mol<ref name=b1>{{cite book| author = Zumdahl, Steven S.|title =Chemical Principles 6th Ed.| publisher = Houghton Mifflin Company| year = 2009| isbn = 0-618-94690-X|page=A21}}</ref>
| Entropy = 107 J·mol<sup>−1</sup>·K<sup>−1</sup> <ref name=b1></ref>
}}
|Section5={{Chembox Hazards
| ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics1589.htm ICSC 1589]
| NFPA-H = 1
| NFPA-F = 0
| NFPA-R = 0
| NFPA-S =
| FlashPt = Ininflamable
| PEL = TWA 15 mg/m<sup>3</sup> (total) TWA 5 mg/m<sup>3</sup> (resp) [sols per forma anhidre]<ref name=PGCH>{{PGCH|0095}}</ref>
| REL = TWA 10 mg/m<sup>3</sup> (total) TWA 5 mg/m<sup>3</sup> (resp) [sols anhidre]<ref name=PGCH/>
| IDLH = N.D.<ref name=PGCH/>
}}
|Section8={{Chembox Related
| OtherCations = [[Sulfat de magnesi]]<br />[[Sulfat d'estronci]]<br />[[Sulfat de bari]]
| OtherFunction_label = [[dessecant]]s
| OtherFunction = [[Clorur de calci]]<br />[[Sulfat de magnesi]]
}}
}}
El '''sulfat de calci''' (CaSO<sub>4</sub>) és un producte químic, format per [[calci]] [[sofre]] i [[oxigen]], habitual en el laboratori i en la indústria. És inodor i sòlid de color blanc. En el seu estat natural, el sulfat de calci sense refinar és una roca translúcida i cristal·lina. Quan està en forma dihidratada (CaSO<sub>4</sub>·2H<sub>2</sub>O) es coneix com a [[guix]]. Pot prendre diferents propietats i aplicacions segons les molècules d'aigua que conté. Quan el [[guix]] s'escalfa a 100 °C, es forma el hemihidratat γ-[[anhidrita]] (la forma gairebé [[anhidre]] CaSO<sub>4</sub>·~0.5H<sub>2</sub>O) que es coneix com guix de París o escaiola. Aquest es fa servir com producte [[dessecador]] i també com a [[floculació|coagulant]] en productes alimentaris com el [[tofu]].<ref>[http://www.soymilkmaker.com/coagulant.html About Tofu Coagulant] Retrieved 9 Jan. 2008.</ref> La forma totalment [[anhidra]] se la coneix com β-[[anhidrita]]. Depenent del mètode de [[calcinació]] del sulfat de calci dihidratat, es distingeixen dos tipus de hemihidratat: alfa-hemihidratat i beta-hemihidratat.<ref name=t>H F W Taylor, ''Cement Chemistry'', Academic Press, 1990, ISBN 0-12-683900-X, pp. 186-187</ref>
| |||