Pengguna:Agung.karjono/Bak pasir/Timbal(II) nitrat: Perbedaan revisi

Tag: Suntingan perangkat seluler Suntingan aplikasi seluler Suntingan aplikasi Android
{{Main|Alotropi belerang}}
[[File:Cyclooctasulfur-above-3D-balls.png|thumb|left|Struktur molekul siklooktasulfur, S<sub>8</sub>]]
Belerang membentuk lebih dari 30 [[alotropi]] padat, lebih banyak daripada unsur lainnya.<ref>{{cite book |title= Solid Sulfur Allotropes Sulfur Allotropes |first1= Ralf |last1= Steudel|first2= Bodo|last2= Eckert|date= 2003 |volume= 230 |pages= 1–80 |doi= 10.1007/b12110 |series= Topics in Current Chemistry |isbn= 978-3-540-40191-9}}</ref> Selain S<sub>8</sub>, diketahui pula beberapa cincin lainnya.<ref>{{cite book |doi=10.1007/3-540-11345-2_10 |last= Steudel|first= R. |date= 1982 |volume= 102 |pages= 149–176 |series=Topics in Current Chemistry |isbn=978-3-540-11345-4|title= Inorganic Ring Systems|chapter= Homocyclic sulfur molecules}}</ref> Dengan mengurangi satu atom dari mahkota menghasilkan S<sub>7</sub>, yang memiliki warna kuning lebih tajam daripada S<sub>8</sub>. Analisis [[Kromatografi Cair Kinerja Tinggi|HPLC]] "unsur belerang" menunjukkan campuran kesetimbangan terutama S<sub>8</sub>, dan ada juga S<sub>7</sub> serta sejumlah kecil S<sub>6</sub>.<ref>{{cite journal |last1= Tebbe |first1= Fred N. |last2= Wasserman |first2= E. |last3= Peet |first3= William G. |last4= Vatvars |first4= Arturs |last5= Hayman |first5= Alan C. |title= Composition of Elemental Sulfur in Solution: Equilibrium of {{chem|S|6}}, S<sub>7</sub>, and S<sub>8</sub> at Ambient Temperatures |journal= Journal of the American Chemical Society|date= 1982 |volume= 104 |issue= 18 |pages= 4971–4972 |doi= 10.1021/ja00382a050}}</ref> Cincin yang lebih besar telah berhasil dibuat, termasuk S<sub>12</sub> dan S<sub>18</sub>.<ref>{{cite journal|last1= Meyer|first1= Beat|title= Solid Allotropes of Sulfur|journal= Chemical Reviews |date= 1964|volume= 64|issue= 4|pages= 429–451|doi= 10.1021/cr60230a004}}</ref><ref>{{cite journal|last1= Meyer|first1= Beat|title= Elemental sulfur|journal= Chemical Reviews|date= 1976|volume= 76|issue= 3|pages= 367–388 |doi= 10.1021/cr60301a003}}</ref>
 
Belerang [[Padatan amorf|amorf]] atau "plastik" dibuat melalui pendinginan cepat lelehan belerang—misalnya, dengan menuangkannya ke dalam air dingin. Studi [[kristalografi sinar-X]] menunjukkan bahwa bentuk amorf dapat memiliki struktur [[heliks]] dengan delapan atom per putaran. Molekul polimer berpilin panjang membentuk zat [[Elastisitas (fisika)|elastis]] berwarna kecoklatan, dan pada fase ruahnya, bentuk ini terasa seperti karet mentah. Bentuk ini bersifat [[Metastabilitas molekul|metastabil]] pada suhu ruang dan secara bertahap kembali ke alotropi molekul kristalnya, yang tidak lagi elastis. Proses ini terjadi dalam jangka waktu jam atau hari, tetapi dapat dipercepat dengan menggunakan katalis.
Larger rings have been prepared, including S<sub>12</sub> and S<sub>18</sub>.<ref>{{cite journal|last1= Meyer|first1= Beat|title= Solid Allotropes of Sulfur|journal= Chemical Reviews |date= 1964|volume= 64|issue= 4|pages= 429–451|doi= 10.1021/cr60230a004}}</ref><ref>{{cite journal|last1= Meyer|first1= Beat|title= Elemental sulfur|journal= Chemical Reviews|date= 1976|volume= 76|issue= 3|pages= 367–388 |doi= 10.1021/cr60301a003}}</ref>
 
[[Amorphous]] or "plastic" sulfur is produced by rapid cooling of molten sulfur—for example, by pouring it into cold water. [[X-ray crystallography]] studies show that the amorphous form may have a [[helix|helical]] structure with eight atoms per turn. The long coiled polymeric molecules make the brownish substance [[elasticity (physics)|elastic]], and in bulk this form has the feel of crude rubber. This form is [[metastability in molecules|metastable]] at room temperature and gradually reverts to crystalline molecular allotrope, which is no longer elastic. This process happens within a matter of hours to days, but can be rapidly catalyzed.
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===PolycationsPolikation anddan polyanionspolianion===
[[image:Lapis lazuli block.jpg|thumb|150px|[[Lapis lazuli]] owes its blue color to a [[trisulfur]] radical anion ({{chem|S|3|-}})]]
 
SulfurBelerang polycationspolikation, {{Chem|S<sub>|8</sub><sup>|2+</sup>}}, {{Chem|S<sub>|4</sub><sup>|2+</sup>}}, anddan {{Chem|S<sub>|16</sub><sup>|2+</sup>}} aredihasilkan producedketika whenbelerang sulfurdireaksikan isdengan reactedoksidator withlemah milddalam oxidisinglarutan agentsasam in a strongly acidic solutionkuat.<ref>Shriver, Atkins. Inorganic Chemistry, Fifth Edition. W. H. Freeman and Company, New York, 2010; pp 416</ref> TheLarutan coloredberwarna solutionsyang produceddihasilkan bydengan dissolvingmelarutkan sulfurbelerang indalam [[{{Ill|asam sulfat pekat berasap|en|oleum]]}} werepertama firstkali reporteddilaporkan aspada early astahun 1804 byoleh C.F. Bucholz, buttetapi thepenyebab causemunculnya ofwarna thedan colorstruktur andpolikation theyang structureterlibat ofbaru theditentukan polycationspada involvedakhir was only determined in the late 1960s1960-an. {{Chem|S<sub>|8</sub><sup>|2+</sup>}} isberwarna deepbiru bluetua, {{Chem|S<sub>|4</sub><sup>|2+</sup>}} iskuning, yellow anddan {{Chem|S<sub>|16</sub><sup>|2+</sup> is}} redmerah.<ref name= "Greenwood"/>
 
[[Trisulfur|Anion radikal]] {{Chem|S|3|-}} menghasilkan warna biru mineral [[lapis lazuli]].[[File:S@CNT.jpg|thumb|Two parallel sulfur chains grown inside a single-wall [[carbon nanotube]] (CNT, a). Zig-zag (b) and straight (c) S chains inside double-wall CNTs<ref>{{cite journal|doi=10.1038/ncomms3162|pmid=23851903|pmc=3717502|title=Conducting linear chains of sulphur inside carbon nanotubes|journal=Nature Communications|volume=4|pages=2162|year=2013|last1=Fujimori|first1=Toshihiko|last2=Morelos-Gómez|first2=Aarón|last3=Zhu|first3=Zhen|last4=Muramatsu|first4=Hiroyuki|last5=Futamura|first5=Ryusuke|last6=Urita|first6=Koki|last7=Terrones|first7=Mauricio|last8=Hayashi|first8=Takuya|last9=Endo|first9=Morinobu|last10=Young Hong|first10=Sang|last11=Chul Choi|first11=Young|last12=Tománek|first12=David|last13=Kaneko|first13=Katsumi|bibcode=2013NatCo...4.2162F}}</ref>]]
The [[Trisulfur|radical anion]] S<sub>3</sub><sup>−</sup> gives the blue color of the mineral [[lapis lazuli]].
[[File:S@CNT.jpg|thumb|Two parallel sulfur chains grown inside a single-wall [[carbon nanotube]] (CNT, a). Zig-zag (b) and straight (c) S chains inside double-wall CNTs<ref>{{cite journal|doi=10.1038/ncomms3162|pmid=23851903|pmc=3717502|title=Conducting linear chains of sulphur inside carbon nanotubes|journal=Nature Communications|volume=4|pages=2162|year=2013|last1=Fujimori|first1=Toshihiko|last2=Morelos-Gómez|first2=Aarón|last3=Zhu|first3=Zhen|last4=Muramatsu|first4=Hiroyuki|last5=Futamura|first5=Ryusuke|last6=Urita|first6=Koki|last7=Terrones|first7=Mauricio|last8=Hayashi|first8=Takuya|last9=Endo|first9=Morinobu|last10=Young Hong|first10=Sang|last11=Chul Choi|first11=Young|last12=Tománek|first12=David|last13=Kaneko|first13=Katsumi|bibcode=2013NatCo...4.2162F}}</ref>]]
 
===Sulfides===